There seems to be a lot of confusion about "mass" and "weight." This is likely due to the fact that the English dictionary has many definitions for each of these words, so they often get used interchangeably in everyday conversation. Most of those definitions are irrelevant for this video because, in a discussion about physics, the physics definition (if it exists) always takes priority. So let's properly define our terms: *Mass - The amount of matter in an object. It's measured in kilograms or slugs.* In Newtonian mechanics, mass stays the same no matter where you are or what you're doing. If my clone is 75 kg on Earth, then he's also 75 kg in an accelerating elevator and in low-Earth orbit and in deep space. The amount of matter inside you doesn't depend on those things. *Weight - The force of gravity from a large object (like a planet). It's measured in pounds or newtons.* That's it. It's just what we call the force of gravity in the situation when one mass is much larger than the other. I defined it at 1:49. This definition can be found in any introductory physics textbook. I even posted a few pictures from those textbooks on Twitter: twitter.com/NickLucid/status/1410763207879368705 Weight is the same no matter what you're doing. In an elevator, my clone has a weight of 165 pounds regardless of acceleration. Weight is _not_ the same regardless of where you are. My clone is 165 pounds on the ground, but he's 140 pounds on the ISS,and he's zero pounds very far from larges masses like stars, planets, and moons. You have to get _really_ far away for this to be a factor though. The top floor of a building isn't far enough. In a building, weight doesn't change. *Which does a scale measure?* Neither. Mass isn't even a force, so there's no way a scale could measure it. _I didn't bring it up in the video because it wasn't relevant._ Since weight is a force, you might expect the scale could measure it, but it doesn't. Scales can only measure forces that require physical contact and weight isn't a contact force. Push scales measure normal force. Pull scales measure tension. Thank you for coming to my TED Talk.
Thank you for the reply. I think we were on the same page on mass and weight based on your reply. But again, regarding the scale measurement, don't you think the tension should be equivalent to the weight (force) as our body rests on it and is stationary? This can only happen when both forces due to gravity and opposing force exerted by scale are equal (This is when we consider tension measuring our weight is the ONLY force opposing our weight).
@The Science Asylum There are some mixed thoughts on how to define weight. You're correct, given your definition. I will stick with the normal force definition of weight because it's more useful, and it's likely what people usually mean by weight. On Earth's surface, weight is almost as invariant as mass, for all practical purposes, so I find it more useful to use a parameter that does significantly change.
Hey thanks for all your vids I’m learning lots and there made really well. Question for a video maybe I’m just learning about electrons and solar power, what is the difference between AC and DC power? And if solar panels create dc current why do we convert it to AC and… do we lose power in transition would it be better to make dc powered appliances. Sorry for silly question never really learnt physics till started researching it recently and I just really want to understand how the hell everything around me works (like solar energy, batteries and “space time”) and why everyone else’s understands it but I don’t I should have done better in school :( Thanks.
@@Wicky89 i hope you are well, i hope i didn't disturb you by replying, as many a times people expect reply from content creator Well ac is easy to manipulate (control) But with newer tech, this difference will become bleak I am a Healthcare Professional by the way
@@ScienceAsylum sir I have one question if An elevator is moving downward with acceleration of say 12 m/S2 then effective g will be now (10-12) which is negative what is feel of this negative acceleration?? Please sir🤔tell m!! I am big fan of yours😊☺️
I once argued with an intellectual that our Weight(not Mass) was a measure Gravity forcing you into an object that stops your free fall. And I was called ignorant lol And this is why I don't argue with people that claim to know everything about something.
@@Krish-jm6ve My comment was about a series of jokes from The Hitchhiker's Guide to the Galaxy. I wasn't commenting about weight at all, including what "weightless" means or how to measure it. But your question is an interesting one. You can't measure weight as a force, so you have to measure it by determining the acceleration vector that is attributable to gravity. I don't know if there is a way to measure it directly, but you can measure it indirectly. It may be possible to measure it almost directly with an accelerometer. I don't know enough about how linear accelerometers work to know for sure.
I remember doing this in my high school physics class and it was probably one of the most interesting lessons we did. The fun lessons like that are what made me love science in general, good teachers know how to keep class interesting.
As a kid I started to have this same suspicion about what scales actually measured when I held the bottom half down and pulled the top half up and watched the dial spin the other way, effectively displaying what I called negative weight. I realized then it was measuring how hard I was pulling or pushing on it. 34 years later you make a video expertly explaining what me as a 10 year old was seeing. What other childhood observations will you help explain next? 😄 Great video!
We had an old spring scale that was effectively a sandwich of two steel plates around a series of springs that were attached to a dial when I was a kid. My mom told me to always pick it up by the bottom plate and never the top plate, which of course meant I had to pick it up by the top plate at least once just to see why I wasn't supposed to and saw the dial do the exact same thing. Also I ended up stretching some of the springs by doing that which meant my stepdad had to go through the tedious process of recalibrating the scale to account for the stretched springs but it was worth it to me.
@@Robert_McGarry_Poems Gotta love how the world's takeaway from dystopian literature was "Oh, so if I voluntarily let Big Brother in my house to watch and listen at all times, I can avoid typing a few characters per day? Sign me up! Alexa, play 'Despacito'!"
@@toby9999 Most people think a 1/3 pound burger is smaller than a 1/4 burger, but it cost more. That's why fast food places took them off the menu. Yes, really.
@@kamikeserpentail3778 You are very wise. There are certain times in life where you just have to cover your eyes and plug your ears and say.... "la la la la la la la" .
For an even more straightforward example of "normal force" on a scale, try putting your scale on an incline. It won't give your entire weight, only the weight that's normal to the surface the scale is sitting on.
@@mids5854 No because it doesn't accelerate. The elevator demonstrated that once acceleration stops (elevator is at full speed) it shows your correct weight again. Then once braking begins, the opposite happens. To confirm planetary rotation as you described, you'd have to stop the rotation or change its speed first.
You can use this effect in an elevator, when carrying grocery bags. When you enter the elevator in the parking floor, place the bags on the floor. Just before you reach your floor and the elevator begins to stop, lift you bags up again and they will be much lighter. This need perfect timing, but it works great.
@@5Siver I never thought of that, a sudden stop instead of decelerating would be awesome. The main question would be "Is it to childish for a 46 year old guy to play in elevators?" and if the answer is yes will that stop me?
2:50 falling sideways. falling and missing... Douglas Adams had this to say about it in The Hitchhikers Guide to the Galaxy... "There is an art to flying, or rather a knack. The knack lies in learning how to throw yourself at the ground and miss. ... Clearly, it is this second part, the missing, that presents the difficulties" According to the Guide, the main thing that flying requires is the ability to throw yourself at the ground and miss. It says to throw yourself forward with all your weight and "the willingness not to mind that it's going to hurt", however it will surely hurt if you fail to miss the ground. The difficulty is in missing the ground, and doing so accidentally, as "deliberately intending to miss the ground" does not work.
Just brilliant. I've been trying to explain this thing about scales, lifts and gravity to my son - but nowhere near as well as this. I can't wait to show him this video when he comes home from school later. Huge thanks, Science Guy!
gravity works both ways so if the scale weighs 50N, the earth feels 50N of force towards the scale too, so in a weird way you really are measuring the "weight" of the earth in relation to the scale. just like you would measure the weight of something in relation to the earth
7:04 I disagree. The buoyancy force on snow and slush are both completely negligible. The reason slush is harder to shovel is that it is more dense, and so a shovel-full has a greater mass than a shovel-full of snow.
"...AND DON'T YOU EVER COME BACK HERE AGAIN!!!" (Kicks Nick off the elevator). Nick rises and falls on a curve. Nick raises his finger, looks at the camera, and says, "Hey, Crazies! What happens when you get kicked in the hiney?"
Very interesting! I had to do this exact experiment as a project for my AP Physics class years ago. Teacher told us to bring a bathroom scale on an elevator, videotape the change in measured weight, and use the footage to calculate the maximum and minimum acceleration of the elevator, exactly as you did here.
Reminds me of the first time when I learned that mass and weight are different things, back in high school in the 90s. Much needed for the new generations.
I was taught the difference between mass and weight back in middle school. Also the science channel. Really there is no excuse to not know, it's literally just basic physics.
I've already went there with my mind... no need to physically take a scale anywhere. Thanks for the superb content; You are truly in my book as the gangsta of science within your respective fields!!!👍🏽🖖🏾
Ahh.. you listened in science class. Well done! I listened in high school science class, and started my college experience as a science major (now a software engineer). So I listened also.. but SO many people haven't been exposed to these ideas. It is why this channel is so wonderful.
Mass does stay constant. Weight can definitely change. You're correct there. Weight just isn't going to change on different floors of a building or in an elevator. You have to get _miles_ above the surface before you'll notice a difference in weight. See the pinned comment for more details.
@@ScienceAsylum This may be true if you use your definitions taken from dictionaries. But if you are a true scientist you know that dictionaries are a garbage place to look for scientific terms and concepts.
Normal in this context means the same thing as perpendicular. In the context of the normal force, the normal and lateral coordinates of a planar surface, and the normal line in optics, it means perpendicular. In the context of linear algebra, think of the idea unit vectors. Normal means divided by magnitude, so that its magnitude equals 1. In linear algebra, they prefer the term orthogonal to mean perpendicular. You might even see the two terms put together, as orthonormal. The ortho part indicates perpendicularity, and the normal part indicates unit length.
This brought back to mind my days of running cranes. The point in time in which a load is lifted that it begins movement “going up” no matter what it is it becomes heavier for a fraction of a second. Depending on the speed at which it’s being hoisted that force can actually overload a crane. I remember learning in my crane certification classes that this point in time of initial force is called the moment of load. Interesting that I I’ve never even considered it since then in the elevator of all places.
I remember my first ever physics lesson in school about 8 years ago. The teacher talked about the difference between mass and weight. I was so fascinated that physics became my favourite subject on that day!
In my language we use this definition: Weight is the force with which the body pushes the support or pulls the suspension. (when we translate our word for weight) But then you call gravitational force weight and our "weight" apparent weight.
Hmm, I also use the definition “weight” is a force caused by the product of mass and acceleration. With a scale using a spring, you measure a force by reading the compression or extraction distance of the spring. To really measure mass, a balance scale is needed where a known mass is balanced against the unknown mass. To work, the whole arrangement need to be under the same acceleration. As we are standing on the earth or moon or any concentrates lump of matter having mass…
@@ScienceAsylum ... You should see the technical documents related with airplane design and testing including the certification requirements. They talk all the time about the aerodynamic loads to be all the time in equilibrium with inertial loads (instead of F=ma), about weight on the wheels (instead of normal force), and about how a 1G flight is unaccelerated but 0G is accelerated. Yuck!!! (and I am an aeronautical engineer and a pilot).
Even a lot of engineering graduates don't understand these fundamentals. This video is gonna be a great help to high schoolers, I remember my own suffering trying to understand this two years ago XD
Ei je Mukherjee dada, egineering college er jawa jonno amader ke JEE dite hoy, tai amader ke ei sob portei hoy, nahole college e admission ki kore pabo??!! 😂
I was literally reading about this yesterday but thanks anyways, for an altogether different video for which I actually landed on this page (The current not taking the path of least resistance). Keep doing the good work.
IKR, this guy is great, he should add some near death experiences and occasional life threatening explosion. He will go down in history as one of the greats!
@@danipent3550 Not by me. The moment a word starts to also mean it's opposite it becomes a useless word, though of course if you have nothing to say to begin with it may not be bothering you.
As I child I thought it would be funny to jump onto a scale. The result was that the meter jumped up and that I gained some intuitive understanding of this.
Sir, you have cleared my confusion of mass and weight. Thanks Sir. I would say only one thing after viewing this [great] video - 'This is the best Science channel on RUclips for [crazy] people like me.'
Hey! I have a bone to pick! I was relegated to watching a rerun because you haven't posted a video in three weeks even though you usually do one every month. (P.S. I still enjoyed it)
Wow. I thought I were doing an odd thing by placing the scale on a spring mattress and bouncing up and down, to see the different readings when going up and when going down. A digital scale doesn't work well, because their sampling rate is too low - one per second, or less. One similarly interesting experiment, is to take a GPS speed meter on a motor boat, and comparing the reading to the speed indicator of the boat, which indicates the speed relative to the water - it uses a small turbine in the water. Or comparing it to the wind speed. Speed is so much more relative than weight... Thanks for the video...
Good and illustrating video as always! What could be added regarding the old fashioned analogue scale, is the much higher weight measured once you step on it and before it stabilizes at static rest (I mean at the static floor now, not in the moving elevator). This is not a measuring error, it is in fact a true measure also due to sudden or moving load (not to be confused with impact loading) 🤓. Now, it's a shame the digital scales do not show the beauty of this as the added acceleration just when you step on the scale is not shown, at least not on my digital scale. The sudden or moving load is not equivalent to the static load measured at rest, even it's not an impact loading that is usually asociated with even shorter load duration.🤓keep up the good work, your videos are truly interesting and illustrates physics in a fascinating, educational and not to forget in a crazyfunny way!👍😊
Physforfun, digital scales often have higher internal resolution and do averaging to reduce noise at the expense of display update rate. They can also do some tricks in the background to null out drift. Fwiw the load cells can be sensitive to shock loads.
Huh, I didn't connect this in my mind till now, but Douglas Adams' thing that flying is throwing yourself at the ground and missing has a basis in reality.
Yeah. I think he has to get credit for that line. He certainly had a unique skill for concocting scientific parodies. There's a passage in one of his HHGTTG books about the anthropic principle, too. He explains it from the perspective of a puddle on the street that suddenly becomes self aware and conscious of its predicament. His improbability drive and restaurant at the edge of the universe are a bit of a stretch, but they're also based on actual science. I think he just loved to make people think while they are being entertained. Like Nick.
My flight instructor always told me the goal in flying is to learn to stay in the middle of the air, and don't go close to the edges except when you desire to terminate the flight.
Actually (nerd clone here) the scale measures the normal force with which YOU push on the scale. Yes, it has equal in magnitude to the normal force with which the scale pushes on you because they are an action-and-reaction pair, but still. The scale can only measure a force acting on it, not a force acting on you. Which is another very good reason why a scale could never measure your weight (which also acts on you, not on the scale). Brilliant video.
@@chuckdeuces911 What a waste of a comment. This is for people interested in science to learn cool factoids, not for idiots to be shaming people that add even more factoids
I was confused after seeing the title but then realised that the word in my language that translates to weight actually doesn't translate to weight at all, at least according to this video. In Lithuanian, "weight" is translated as "svoris" and is used that way in linguistics, dictionaries, every day language, etc. That's the official translation. However, it seems that "weight" does not mean "svoris" according to this video. We use "svoris" to describe the force that an object affects another surface, say, the ground or the scale, which is what you called the "push". We use the word "sunkis" to describe the force that gravity pulls you downward with (or towards another mass). And "sunkis" translates to "heaviness" in English instead of "weight". So the official translation of "weight" actually doesn't mean weight in Lithuanian. And the official translation of "heaviness" actually should be the translation of "weight". Interesting how linguistics and physics can differ so much, especially when different languages are concerned. EDIT: After some digging, I found that it's English physicists that's to blame for the misconception of weight and the weird "mistranslation" between English and Lithuanian. The word "weight" comes from Old-Germanic "wegan" which comes from Proto-Indo-European "wegh". And it means to move, carry, lift. So English physicists incorrectly chose the word "weight" to represent the force of gravity when it should have represented the push force that objects affect surfaces such as the ground or the scales since it's exactly THAT force that ancient people felt when they came up with the word "wegh/wegan". Apparent weight should be THE weight and what is weight in physics should probably use another word. So maybe it's not the people who say scales measure weight who are wrong but rather physicists who chose the wrong word?
EDIT to add: I thought this a brand spanking new video, and assumed I was getting in on the ground floor. Turns out, this video is a month old and lots of comments have probably addressed by point. I'm leaving it here anyway because why not. 😁 EDIT #2: Just read the pinned comment. You wrote: "Mass isn't even a force, so there's no way a scale could measure it." Of course a scale can measure mass, because scales utilize gravity. All you to know is what units the scale uses, and the g "force" present. If "F", as measured by the scale, is 1 kg, and "a" is 32 fps^2 (1 g, the baseline reference for kg "weight"), then a scale measuring 1 kg of weight is measuring 1 kg of mass. To measure mass with the same scale, but at a different g, would require a simple conversion. Now, this not a DIRECT measurement of mass. (Perhaps that is what you meant.) But a scale CAN be used to measure a small object's mass, just as studying the orbit of a satellite can be used to measure a star or planet's mass, because both methods use gravity. Now, on to my original post!...........: 4:47 "Again, actual weight doesn't change. Elevator Clone is 165 lbs that whole time." And THERE is the fallacy at the core of this video's argument. Elevator Clone's MASS never changes, but his WEIGHT does, because weight depends on the environment. The accelerations at the start and end of his elevator journey, as evidenced by the movement of the needle, change his WEIGHT. Since weight depends on the inertial particulars of the environment, there is no "actual" or "apparent weight" to agonize over. There is only "weight weight", as measured by the scale. Weight is simply a manifestation of F=ma. A body in free-fall in a vacuum (and this includes orbit) has no acceleration acting on it and is, therefore, weightless. The only way Mr. Clone, falling to Earth from outside the atmosphere, would have weight is if you could put a scale between him and the Earth, and put a rocket under the scale to exactly counter the g "force" at that distance -- which is precisely what a bathroom scale does. (Except that, instead of a rocket, there's the bathroom floor of the house, built on solid ground.) Mr. Clone's 165 lbs happens to be 165 lbs only when he's measuring it where it happens to be 165 lbs. It would be roughly 28 lbs on the surface of the Moon. No matter where he is when he steps on the scale, whatever the scale reads, that's his WEIGHT.
"There is an art to flying, or rather a knack. The knack lies in learning how to throw yourself at the ground and miss." -- Hitchhiker's Guide to the Galaxy
Old Timey Scientist "Look at my wonderful invention, it tells you how much things weigh" The Science A (Pushing and pulling mannicly on spring watching dial) Old TS (Takes back scale, locks in timeless vacuum chamber) "You're using it wrong!" The SA "But...... It was telling me something" I dunno why this episode made me laugh so hard, maybe I'm weigh too much of a nerd.
I will agree, you can’t feel “weight” what you feel is the normal force for the required acceleration. As in an aircraft, in a pull-up, “pulling gs” what your are feeling is the normal force, being provided by the seat of the aircraft, to accelerate you. Hence, if you are sitting on a scale in the aircraft you will see the required force to accelerate you with the aircrafts changing flight path (velocity)
@@AFmedic what you are feeling is the floor not only accelerating your mass, but the mass of the “fat ass”. The force is transmitted from the floor, thru your foot, to the fat ass.
@@antred11 It depends on how you define weight. Most people learn that weight is the pull of gravity, and in that case, you CANNOT feel your weight. You cannot feel the difference between accelerating through deep space at 9.8 m/s^2, and standing stationary in Earth's gravitational field of 9.8 N/kg. You feel the constraint force that keep you at rest in your immediate environment, and you instinctively assume the constraint force opposes your weight. If instead, you define weight as your reaction to a constraint force, then indeed you do feel it. In any case, you ultimately feel constraint forces, and you cannot feel the force of gravity.
I've taken many physics courses in my engineering education and never had an issue with the idea of weight. We always calculated and described weight as the product of mass in the presence of a gravitational field. Weight is an object's mass multiplied by acceleration of gravity. Some of this seems to muddy that concept.
If you didn't notice that this channel is for people to learn not for knowledgeable people to humbly brag about how smart they already are so congrats you got an education to come to RUclips a flaunt.
Newtonian physics vs General Relativity. He is basically showing how acceleration is the same as gravity in the elevator experiment. The scale measure a compression force of the feet and the base. Manufacturers of scales use a standard weight. There is a actual weight that is measured to be exactly 1 pound or 1KG. Then the manufacturer uses that to calibrate the scale so that when we stand on it with the expected 1G of earth we can calculate our weight. But it’s not measuring weight, but the compression of the force of gravity of earth and the gravity of our bodies compressing the scale. The scale is then designed to represent that force as weight based on that standard weight it was calibrated to.
wow i just found you through your other channel where you talked about autism, i was diagnosed later than usual as well and it was tough. Seeing what you have achieved here and your great communication skills it gives me some hope :)
I could hear you talking with your wife "I need to push a scale on your back." "Why?" [Inquisitive eyebrow raised] "Because SCIENCE! But in all actuality, I want to explain to the Crazies the difference of "weight" and push force." "OK, just don't get my face, I haven't done my makeup yet."
I really like your style of teaching. I have watched almost all of your videos. I really used to like the style of the one which you made a year back around or so would like to see more of it.
There seem to be at least three different definitions of the word "weight". 1) Mass m in kg (as understood by most people and intended to be measured by the bathroom scales) 2) Force of gravity, mg in Newtons, as defined by US/EU textbooks 3) Force applied to a support, m(g+p) in Newtons, as defined by some Eastern European textbooks.
you don't exert a force on the earth at all, because then they would cancel each other out - "gravity" that causes your weight is caused by your acceleration from the earth pushing you up to stop you from falling
Dude you're so good at getting angry with your nerd clone, lmao. I bet a lot of work went into figuring out how to time that just right, with the i-i-i -it, and head shaking. Or maybe your just a brilliant genius who had an innate sense for how to deal with nerd clone.
I'd say the snow vs slush thing is much more about density than bouyancy: A shovel full of snow is going to be less dense and contain less mass than a shovel full of slush.
Yep. A very weird, misleading example. The point about bouyancy effect would be that shovelling 1 kg of snow would be indetectibly (to human senses) easier than shovelling 1kg of slush, as the displaced air due to the larger volume of 1kg of snow vs 1 kg of slush would be provide some tiny bouyancy effect in the vertical direction. In reality the greater wind resistance of moving a 1kg mass of snow vs a 1kg mass of slush would probably exceed the bouyancy effect. I'd say "leave it to 'The Science Asylum' to calculate if the wind resistance effect would be > or < the bouyacy effect in practice, but I doubt they would get the calculations correct...
PROFESSOR!! I shouldn't say your last name here!! You inspired me with your physics 1 class and I passed the Civil PE in Water Resources & Environmental this past October. I think of you fondly, and often. The history of physics is still the best thing I've ever learned and I have you to thank for my career path. I found this channel while looking for you so that I might thank you.
this is the first vid I see and subbed immediately. Very interesting and very well explained, also it's refreshing to change perspective on the mundane.
I wish I could double like this video. I never knew that the orbit of the space station gave the appearance of weightlessness. It makes sense. They’re in an almost endless fall.
I believe that you may be confusing the terms weight and mass. Mass is the measure of how much matter makes up an object. Usually measured in grams. (g) Weight is a measurement an object's mass multiplied by the gravity/acceleration (m/s2) acting upon that object. Usually measured in Newtons. (N) or (g*m/s2) Since most Americans measure their weight in pounds, which have the same type of units as newtons, (mass x distance / time squared) and pounds use earths gravity as a constant of 1. It is very easy to confuse the two very different types of measurements. The average bathroom scale is doing this calculation for you and when you take the scale in the elevator you are changing your acceleration and thus changing the gravity constant that the scale needs to give you your appropriate weight.
There are essentially only 2 forces: PUSH & PULL (even the strong & weak forces) are essentially push (repulsion) / pull (attraction). A force can be described as the influence that cab change the motion of an object. It has both magnitude & direction. Mass = quantity of matter ( = both potential AND kinetic energy) F = ma DOES NOT EQUAL F = Gm1m2/r^2 F=ma = PUSH F=Gm1m2/r^2 = PULL LET: speed of light = 3e8 m/s Plank length (PL) = 1.616e-35m Plank mass (PM) = 2.18e-8 kg Smallest possible object is one with plank length = 1.616e-35 m & plank mass = 2.18e-8 kg G = 6.67e-11 m^3/(kg.s^2) To solve: G = c^2 x PL / PM Check units = c^2 = m^2/s^2; PL = m, PM = kg G = m^3 / (s^2.kg) = c^2 = 9e16 PL/PM = 7.43e-28 It is known that 2 objects each with a given mass will attract one another. So, G. the gravitational constant, describes the force of attraction the smallest possible object in the universe exerts. If you assume all objects are bound to each other then you may even call it a torque.
in wikipedia article "mass versus weight! we can find "The mass of an object is a measure of the object’s inertial property, or the amount of matter it contains. The weight of an object is a measure of the force exerted on the object by gravity, or the force needed to support it. " that are the correct definitions
Whenever I travel in an elevator while standing on bathroom scales I'm always holding on to a bunch of six helium-filled balloons. It's a quirk of mine. Whatcha gotta say about that effect, mister? Huh, smarty-pants?
thats a good one. it would still be push force measured I guess, with the balloons affecting your weight and your mass staying the same (unless you added the mass to your body)
Dr Nick, you're one of the best at explaining Physics. Would you consider making a series of video about Loop Quantum Gravity? Something about Loops as solution to the Wheeler-Devitt equation, Spin Networks, Volume as a quantum property of a node and Area as quantum property of a link, the emergence of "Space" from a Spin Network, Spin Foam and the emergence of "Time" from the evolution of a Spin Network. LQG is a very neglected topic, it's very hard to find good material...
There seems to be a lot of confusion about "mass" and "weight." This is likely due to the fact that the English dictionary has many definitions for each of these words, so they often get used interchangeably in everyday conversation. Most of those definitions are irrelevant for this video because, in a discussion about physics, the physics definition (if it exists) always takes priority. So let's properly define our terms:
*Mass - The amount of matter in an object. It's measured in kilograms or slugs.*
In Newtonian mechanics, mass stays the same no matter where you are or what you're doing. If my clone is 75 kg on Earth, then he's also 75 kg in an accelerating elevator and in low-Earth orbit and in deep space. The amount of matter inside you doesn't depend on those things.
*Weight - The force of gravity from a large object (like a planet). It's measured in pounds or newtons.*
That's it. It's just what we call the force of gravity in the situation when one mass is much larger than the other. I defined it at 1:49. This definition can be found in any introductory physics textbook. I even posted a few pictures from those textbooks on Twitter: twitter.com/NickLucid/status/1410763207879368705 Weight is the same no matter what you're doing. In an elevator, my clone has a weight of 165 pounds regardless of acceleration. Weight is _not_ the same regardless of where you are. My clone is 165 pounds on the ground, but he's 140 pounds on the ISS,and he's zero pounds very far from larges masses like stars, planets, and moons. You have to get _really_ far away for this to be a factor though. The top floor of a building isn't far enough. In a building, weight doesn't change.
*Which does a scale measure?*
Neither. Mass isn't even a force, so there's no way a scale could measure it. _I didn't bring it up in the video because it wasn't relevant._ Since weight is a force, you might expect the scale could measure it, but it doesn't. Scales can only measure forces that require physical contact and weight isn't a contact force. Push scales measure normal force. Pull scales measure tension.
Thank you for coming to my TED Talk.
Thank you for the reply. I think we were on the same page on mass and weight based on your reply.
But again, regarding the scale measurement, don't you think the tension should be equivalent to the weight (force) as our body rests on it and is stationary? This can only happen when both forces due to gravity and opposing force exerted by scale are equal (This is when we consider tension measuring our weight is the ONLY force opposing our weight).
@The Science Asylum There are some mixed thoughts on how to define weight. You're correct, given your definition. I will stick with the normal force definition of weight because it's more useful, and it's likely what people usually mean by weight. On Earth's surface, weight is almost as invariant as mass, for all practical purposes, so I find it more useful to use a parameter that does significantly change.
Where I live we measure weight in kg 😉
Hey thanks for all your vids I’m learning lots and there made really well.
Question for a video maybe
I’m just learning about electrons and solar power, what is the difference between AC and DC power? And if solar panels create dc current why do we convert it to AC and… do we lose power in transition would it be better to make dc powered appliances.
Sorry for silly question never really learnt physics till started researching it recently and I just really want to understand how the hell everything around me works (like solar energy, batteries and “space time”) and why everyone else’s understands it but I don’t I should have done better in school :(
Thanks.
@@Wicky89 i hope you are well, i hope i didn't disturb you by replying, as many a times people expect reply from content creator
Well ac is easy to manipulate (control)
But with newer tech, this difference will become bleak
I am a Healthcare Professional by the way
You're a braver man than I referring to your wife as "or whatever" 🤣
😂
True! 😂
Also, I don't this is the way a man should push on a woman. 🤣
@@rauldumitrascu4929 well, the evidence suggests that she's no push-over.
@@ScienceAsylum sir I have one question if An elevator is moving downward with acceleration of say 12 m/S2 then effective g will be now (10-12) which is negative what is feel of this negative acceleration?? Please sir🤔tell m!! I am big fan of yours😊☺️
“You don’t feel weight, you only feel pushes and pulls”… man I feel enlightened, thanks for the video
but isn't weight itself just "pull"
I read that precisely when he said it.
I once argued with an intellectual that our Weight(not Mass) was a measure Gravity forcing you into an object that stops your free fall. And I was called ignorant lol
And this is why I don't argue with people that claim to know everything about something.
We also don't feel temperature, but the heat transfer in or out of our bodies.
@@tektrixter Eat a lot and stand still, do nothing for a while after eat then you will feel it, guaranteed.
I'm reminded of Hitchhiker's Guide to the Galaxy which states that flying requires learning how to throw yourself at the ground and miss...
That's the thought that went through my mind, too.
Turns out that's how to orbit.
The important thing is for the astronauts to be regularly distracted so they forget to hit the ground on each orbit.
like an orbit
@@ericwiddison7523 So how can weight be measured when you "feel" weightlessness ?
@@Krish-jm6ve My comment was about a series of jokes from The Hitchhiker's Guide to the Galaxy. I wasn't commenting about weight at all, including what "weightless" means or how to measure it.
But your question is an interesting one. You can't measure weight as a force, so you have to measure it by determining the acceleration vector that is attributable to gravity. I don't know if there is a way to measure it directly, but you can measure it indirectly.
It may be possible to measure it almost directly with an accelerometer. I don't know enough about how linear accelerometers work to know for sure.
I remember doing this in my high school physics class and it was probably one of the most interesting lessons we did. The fun lessons like that are what made me love science in general, good teachers know how to keep class interesting.
As a kid I started to have this same suspicion about what scales actually measured when I held the bottom half down and pulled the top half up and watched the dial spin the other way, effectively displaying what I called negative weight. I realized then it was measuring how hard I was pulling or pushing on it. 34 years later you make a video expertly explaining what me as a 10 year old was seeing. What other childhood observations will you help explain next? 😄 Great video!
We had an old spring scale that was effectively a sandwich of two steel plates around a series of springs that were attached to a dial when I was a kid. My mom told me to always pick it up by the bottom plate and never the top plate, which of course meant I had to pick it up by the top plate at least once just to see why I wasn't supposed to and saw the dial do the exact same thing. Also I ended up stretching some of the springs by doing that which meant my stepdad had to go through the tedious process of recalibrating the scale to account for the stretched springs but it was worth it to me.
So you broke your parents scales? Lol
@@Dargonhuman lol literally what I said 1st guy did broke scales. Your mom learned not to tell kids not to do stuff lol.
Careful. Using the scale other than as intended may void its warranty.
Whoa! Even for a bathroom scale!
This is why I love kitchen scales, because the manufacturer can't possibly know WHICH herb I'm weighing out in my kitchen...
@@superking208 Cell phones...I mean two decades ago, I would have totally agreed.
@@Robert_McGarry_Poems Gotta love how the world's takeaway from dystopian literature was "Oh, so if I voluntarily let Big Brother in my house to watch and listen at all times, I can avoid typing a few characters per day? Sign me up! Alexa, play 'Despacito'!"
True.
"This isn't flying, it's falling with style".
Hahahahha
Ohhhh, man. I was gonna say that😉
I don't think it's a good intuition to say an orbit is falling but the earth curves away. I'd rather go with falling is an extremely eccentric orbit.
Like the end of Dark Star?
So I've just learned that scales work exactly how I've known they have for my entire life. I thought this video was going to blow my mind or something
Nope, just 10 minutes of quibbling about the definition of weight
It didn't blow your mind because you already knew it but realise most people don't know it. Most people ate clueless of basic physics.
@@toby9999 Most people think a 1/3 pound burger is smaller than a 1/4 burger, but it cost more.
That's why fast food places took them off the menu. Yes, really.
@@mayorb3366 I refuse to believe it, for my own mental safety.
@@kamikeserpentail3778 You are very wise.
There are certain times in life where you just have to cover your eyes and plug your ears and say.... "la la la la la la la" .
For an even more straightforward example of "normal force" on a scale, try putting your scale on an incline. It won't give your entire weight, only the weight that's normal to the surface the scale is sitting on.
Put it on a slope, east to west and west to east... with an accurate enough scale you should be able to confirm planitary rotation.
@@mids5854 No because it doesn't accelerate. The elevator demonstrated that once acceleration stops (elevator is at full speed) it shows your correct weight again. Then once braking begins, the opposite happens. To confirm planetary rotation as you described, you'd have to stop the rotation or change its speed first.
@@KarstenJohansson Superman did that all the time when I was a kid in the 60s.
You can use this effect in an elevator, when carrying grocery bags. When you enter the elevator in the parking floor, place the bags on the floor. Just before you reach your floor and the elevator begins to stop, lift you bags up again and they will be much lighter. This need perfect timing, but it works great.
I find it fun to try to jump just as the elevator stops, you can get some serious "height" in relation to the elevator floor.
@@spindoctor6385 you can also cause the elevator to make an emergency stop.
@@5Siver I never thought of that, a sudden stop instead of decelerating would be awesome.
The main question would be "Is it to childish for a 46 year old guy to play in elevators?" and if the answer is yes will that stop me?
@@spindoctor6385 if you won't have a flight to miss (like I had) then you're fine :)
kawaii uwu
“The Guide says there is an art to flying", said Ford, "or rather a knack. The knack lies in learning how to throw yourself at the ground and miss.”
the Guide is useful in so many ways…
"Falling but missing" is some hitchhikers guide to the galaxy stuff
@@SeanChandlerSF Me too! :D)
try Terry Pratchett
2:50 falling sideways. falling and missing... Douglas Adams had this to say about it in The Hitchhikers Guide to the Galaxy...
"There is an art to flying, or rather a knack. The knack lies in learning how to throw yourself at the ground and miss. ... Clearly, it is this second part, the missing, that presents the difficulties"
According to the Guide, the main thing that flying requires is the ability to throw yourself at the ground and miss. It says to throw yourself forward with all your weight and "the willingness not to mind that it's going to hurt", however it will surely hurt if you fail to miss the ground. The difficulty is in missing the ground, and doing so accidentally, as "deliberately intending to miss the ground" does not work.
I am very happy folks noticed this!
I believe this is the reason airlines have been misplacing luggage since that book was published.
@@AlexandarHullRichter in times like that, all you can really do is smile, wave, and thank them for all the fish.
Just brilliant. I've been trying to explain this thing about scales, lifts and gravity to my son - but nowhere near as well as this. I can't wait to show him this video when he comes home from school later. Huge thanks, Science Guy!
Glad it was helpful! 🤓
what makes this funny is that I have an elevator scale in my bathroom.
Oh cool, I have a Kitchen scale in my livingroom.
I have a tiny scale in my nightstand drawer to measure how much push my bag of flower I just got has in it
Why do you call it an elevator scale? Because it goes up and down?
@@ChronicSkater me too!
o.0
Turn the scale upside down. The Earth now weighs ~your earth weight~ on planet You.
Doesn’t this only work in Soviet Russia?
Vsauce did it!
gravity works both ways so if the scale weighs 50N, the earth feels 50N of force towards the scale too, so in a weird way you really are measuring the "weight" of the earth in relation to the scale. just like you would measure the weight of something in relation to the earth
@@captaincruise8796 aaahhhhh I was gonna do that!
u don't have to flip the scale upside-down for that. That will just make it harder to read xD
WHY NOT ?!? Cheers!
7:04 I disagree. The buoyancy force on snow and slush are both completely negligible. The reason slush is harder to shovel is that it is more dense, and so a shovel-full has a greater mass than a shovel-full of snow.
Thanks for the fantastic idea for my IB Physics Class!
I used to do this in my physics classes all the time!
Could picture Nick getting kicked out of a building for playing in the elevator with a scale. 🤣
The building's caretaker was not so Lucid about it either.
😂 I filmed it at a school I used to work at in a science department elevator. It wouldn't have looked as weird as you're imagining.
@@ScienceAsylum Hey, didn't you graduate... And then work here?
"...AND DON'T YOU EVER COME BACK HERE AGAIN!!!" (Kicks Nick off the elevator). Nick rises and falls on a curve. Nick raises his finger, looks at the camera, and says, "Hey, Crazies! What happens when you get kicked in the hiney?"
Don't worry, it's nust a clone!
Very interesting! I had to do this exact experiment as a project for my AP Physics class years ago. Teacher told us to bring a bathroom scale on an elevator, videotape the change in measured weight, and use the footage to calculate the maximum and minimum acceleration of the elevator, exactly as you did here.
It's a great student project!
Reminds me of the first time when I learned that mass and weight are different things, back in high school in the 90s. Much needed for the new generations.
I was taught the difference between mass and weight back in middle school. Also the science channel. Really there is no excuse to not know, it's literally just basic physics.
I've already went there with my mind... no need to physically take a scale anywhere. Thanks for the superb content; You are truly in my book as the gangsta of science within your respective fields!!!👍🏽🖖🏾
You have some interesting characters on your staff. 💫🙇🏻
I honestly thought that's what weight meant. All my life I said weight changes with forces, mass stays constant.
Ahh.. you listened in science class. Well done!
I listened in high school science class, and started my college experience as a science major (now a software engineer). So I listened also.. but SO many people haven't been exposed to these ideas. It is why this channel is so wonderful.
Mass does stay constant. Weight can definitely change. You're correct there. Weight just isn't going to change on different floors of a building or in an elevator. You have to get _miles_ above the surface before you'll notice a difference in weight. See the pinned comment for more details.
Imagine if we were to walk around on jupiter.. our mass is the same as it was on earth, but we would weigh more on jupiter..??? 🤯
@@ScienceAsylum This may be true if you use your definitions taken from dictionaries. But if you are a true scientist you know that dictionaries are a garbage place to look for scientific terms and concepts.
No. That's what Nick's clone would say!
[Nick: Now let's weigh in on this thing called 'relativistic' mass crazies!😁]
1:19 I love the way that Nerd Clone always looks at the camera after saying something technically correct.
Thank you for explaining the difference between normal and perpendicular. I always wondered.
But he only described the special case of euclidian space. Does true perpendicular actually exist???
Normal in this context means the same thing as perpendicular. In the context of the normal force, the normal and lateral coordinates of a planar surface, and the normal line in optics, it means perpendicular.
In the context of linear algebra, think of the idea unit vectors. Normal means divided by magnitude, so that its magnitude equals 1. In linear algebra, they prefer the term orthogonal to mean perpendicular. You might even see the two terms put together, as orthonormal. The ortho part indicates perpendicularity, and the normal part indicates unit length.
This brought back to mind my days of running cranes. The point in time in which a load is lifted that it begins movement “going up” no matter what it is it becomes heavier for a fraction of a second. Depending on the speed at which it’s being hoisted that force can actually overload a crane. I remember learning in my crane certification classes that this point in time of initial force is called the moment of load. Interesting that I I’ve never even considered it since then in the elevator of all places.
I remember my first ever physics lesson in school about 8 years ago. The teacher talked about the difference between mass and weight. I was so fascinated that physics became my favourite subject on that day!
In my language we use this definition: Weight is the force with which the body pushes the support or pulls the suspension. (when we translate our word for weight) But then you call gravitational force weight and our "weight" apparent weight.
That sounds a lot like the _engineers_ definition for "weight."
@Thijs Janssen Weight and gravity are the same thing in physics.
@@ScienceAsylum
"Well, technically..."
Hmm, I also use the definition “weight” is a force caused by the product of mass and acceleration. With a scale using a spring, you measure a force by reading the compression or extraction distance of the spring. To really measure mass, a balance scale is needed where a known mass is balanced against the unknown mass. To work, the whole arrangement need to be under the same acceleration. As we are standing on the earth or moon or any concentrates lump of matter having mass…
@@ScienceAsylum ... You should see the technical documents related with airplane design and testing including the certification requirements. They talk all the time about the aerodynamic loads to be all the time in equilibrium with inertial loads (instead of F=ma), about weight on the wheels (instead of normal force), and about how a 1G flight is unaccelerated but 0G is accelerated. Yuck!!! (and I am an aeronautical engineer and a pilot).
Even a lot of engineering graduates don't understand these fundamentals. This video is gonna be a great help to high schoolers, I remember my own suffering trying to understand this two years ago XD
Seriously? I recognized this on my own like in high school.
Ei je Mukherjee dada, egineering college er jawa jonno amader ke JEE dite hoy, tai amader ke ei sob portei hoy, nahole college e admission ki kore pabo??!! 😂
@@brainboxanky1729
সবাই পরে কিন্তু কয়জন বোঝে😅
@@brainboxanky1729 😍 বাংলা কমেন্ট ।
আপনি কোন ক্লাস এ এখন?
কোন জেলা?
@@raj-m
এইতো JEE দিচ্ছি
3:25 footage of astronauts performing important science on the ISS
Yep. We call it conservation of angular momentum.
@@adb012 its simpler to call it Torque.
I was worried that guy spinning would bump his head!
@@NamedSoni not the same thing....
3:02 "Flying is easy, just throw yourself at the ground and miss" --Douglas Adams
I was literally reading about this yesterday but thanks anyways, for an altogether different video for which I actually landed on this page (The current not taking the path of least resistance).
Keep doing the good work.
This channel is so good it literally explains physics in a fun and understandable way
IKR, this guy is great, he should add some near death experiences and occasional life threatening explosion. He will go down in history as one of the greats!
Stop! Just stop using 'literally' in that incorrect manner.
@@danipent3550 Not by me. The moment a word starts to also mean it's opposite it becomes a useless word, though of course if you have nothing to say to begin with it may not be bothering you.
@@psibarpsi I’m not English bruv
@@BlacksmithTWD I’m not English and I was using it as emphasis
Didn't encounter this question yet but thank you for making my concept more clear.❤️
3:03 HOLY F! The Hitchhiker’s Guide to the Galaxy was right about flying!
was much more interesting than I thought. Dude youre making great videos!
Thanks! 🤓
Your videos are becoming more and more pieces of art.
Thanks 🙂
cool! thx for helping me in my 3rd secondary year dynamics
keep it up man !
As I child I thought it would be funny to jump onto a scale. The result was that the meter jumped up and that I gained some intuitive understanding of this.
Sir, you have cleared my confusion of mass and weight. Thanks Sir.
I would say only one thing after viewing this [great] video - 'This is the best Science channel on RUclips for [crazy] people like me.'
Hey! I have a bone to pick! I was relegated to watching a rerun because you haven't posted a video in three weeks even though you usually do one every month. (P.S. I still enjoyed it)
January's video goes up tomorrow 👍
that little throw away few seconds finnaly allowed me to know what 'normal' is in forces. and we alllll forget about buoyancy... most times.
“There is an art to flying, or rather a knack. The knack lies in learning how to throw yourself at the ground and miss.” - Douglas Adama
*Elevator barely has room*
Me: *pulls up with a bathroom scale FOR SCIENCE*
Wow. I thought I were doing an odd thing by placing the scale on a spring mattress and bouncing up and down, to see the different readings when going up and when going down. A digital scale doesn't work well, because their sampling rate is too low - one per second, or less.
One similarly interesting experiment, is to take a GPS speed meter on a motor boat, and comparing the reading to the speed indicator of the boat, which indicates the speed relative to the water - it uses a small turbine in the water. Or comparing it to the wind speed. Speed is so much more relative than weight...
Thanks for the video...
Yeah, it was really important that the scale was analog. A digital scale would have been a huge pain.
This is a very clever video right from the title! I salute you sir!
Thanks 🙇♂️
“The channel where you learn about physics and have fun doing it!”
All of RUclips should do this.
Good and illustrating video as always! What could be added regarding the old fashioned analogue scale, is the much higher weight measured once you step on it and before it stabilizes at static rest (I mean at the static floor now, not in the moving elevator). This is not a measuring error, it is in fact a true measure also due to sudden or moving load (not to be confused with impact loading) 🤓. Now, it's a shame the digital scales do not show the beauty of this as the added acceleration just when you step on the scale is not shown, at least not on my digital scale. The sudden or moving load is not equivalent to the static load measured at rest, even it's not an impact loading that is usually asociated with even shorter load duration.🤓keep up the good work, your videos are truly interesting and illustrates physics in a fascinating, educational and not to forget in a crazyfunny way!👍😊
Physforfun, digital scales often have higher internal resolution and do averaging to reduce noise at the expense of display update rate. They can also do some tricks in the background to null out drift. Fwiw the load cells can be sensitive to shock loads.
@@anullhandle ok, thanks- nice to know😊
As a kid we liked to jump when the elevator started moving. You will either go up more or less than expected.
Huh, I didn't connect this in my mind till now, but Douglas Adams' thing that flying is throwing yourself at the ground and missing has a basis in reality.
Yeah. I think he has to get credit for that line. He certainly had a unique skill for concocting scientific parodies. There's a passage in one of his HHGTTG books about the anthropic principle, too. He explains it from the perspective of a puddle on the street that suddenly becomes self aware and conscious of its predicament. His improbability drive and restaurant at the edge of the universe are a bit of a stretch, but they're also based on actual science. I think he just loved to make people think while they are being entertained. Like Nick.
My flight instructor always told me the goal in flying is to learn to stay in the middle of the air, and don't go close to the edges except when you desire to terminate the flight.
@@walterbrown8694 Good advice.
wow u blew my mind i love the way you explain things
What a fantastic post!!!! thank you :)
Till this day I don't regret ever subscribing!
Actually (nerd clone here) the scale measures the normal force with which YOU push on the scale. Yes, it has equal in magnitude to the normal force with which the scale pushes on you because they are an action-and-reaction pair, but still. The scale can only measure a force acting on it, not a force acting on you. Which is another very good reason why a scale could never measure your weight (which also acts on you, not on the scale).
Brilliant video.
Exactly lol
What a waste of a comment. This is for regular people to learn what they haven't it's not a channel for 'experts'..
@@chuckdeuces911 What a waste of a comment. This is for people interested in science to learn cool factoids, not for idiots to be shaming people that add even more factoids
I was confused after seeing the title but then realised that the word in my language that translates to weight actually doesn't translate to weight at all, at least according to this video.
In Lithuanian, "weight" is translated as "svoris" and is used that way in linguistics, dictionaries, every day language, etc. That's the official translation. However, it seems that "weight" does not mean "svoris" according to this video. We use "svoris" to describe the force that an object affects another surface, say, the ground or the scale, which is what you called the "push". We use the word "sunkis" to describe the force that gravity pulls you downward with (or towards another mass). And "sunkis" translates to "heaviness" in English instead of "weight".
So the official translation of "weight" actually doesn't mean weight in Lithuanian. And the official translation of "heaviness" actually should be the translation of "weight". Interesting how linguistics and physics can differ so much, especially when different languages are concerned.
EDIT: After some digging, I found that it's English physicists that's to blame for the misconception of weight and the weird "mistranslation" between English and Lithuanian. The word "weight" comes from Old-Germanic "wegan" which comes from Proto-Indo-European "wegh". And it means to move, carry, lift. So English physicists incorrectly chose the word "weight" to represent the force of gravity when it should have represented the push force that objects affect surfaces such as the ground or the scales since it's exactly THAT force that ancient people felt when they came up with the word "wegh/wegan". Apparent weight should be THE weight and what is weight in physics should probably use another word. So maybe it's not the people who say scales measure weight who are wrong but rather physicists who chose the wrong word?
Etymology is so interesting!! 🤓
Mass!
EDIT to add: I thought this a brand spanking new video, and assumed I was getting in on the ground floor. Turns out, this video is a month old and lots of comments have probably addressed by point. I'm leaving it here anyway because why not. 😁
EDIT #2: Just read the pinned comment. You wrote: "Mass isn't even a force, so there's no way a scale could measure it."
Of course a scale can measure mass, because scales utilize gravity. All you to know is what units the scale uses, and the g "force" present. If "F", as measured by the scale, is 1 kg, and "a" is 32 fps^2 (1 g, the baseline reference for kg "weight"), then a scale measuring 1 kg of weight is measuring 1 kg of mass. To measure mass with the same scale, but at a different g, would require a simple conversion.
Now, this not a DIRECT measurement of mass. (Perhaps that is what you meant.) But a scale CAN be used to measure a small object's mass, just as studying the orbit of a satellite can be used to measure a star or planet's mass, because both methods use gravity.
Now, on to my original post!...........:
4:47 "Again, actual weight doesn't change. Elevator Clone is 165 lbs that whole time."
And THERE is the fallacy at the core of this video's argument. Elevator Clone's MASS never changes, but his WEIGHT does, because weight depends on the environment. The accelerations at the start and end of his elevator journey, as evidenced by the movement of the needle, change his WEIGHT. Since weight depends on the inertial particulars of the environment, there is no "actual" or "apparent weight" to agonize over. There is only "weight weight", as measured by the scale.
Weight is simply a manifestation of F=ma. A body in free-fall in a vacuum (and this includes orbit) has no acceleration acting on it and is, therefore, weightless. The only way Mr. Clone, falling to Earth from outside the atmosphere, would have weight is if you could put a scale between him and the Earth, and put a rocket under the scale to exactly counter the g "force" at that distance -- which is precisely what a bathroom scale does. (Except that, instead of a rocket, there's the bathroom floor of the house, built on solid ground.)
Mr. Clone's 165 lbs happens to be 165 lbs only when he's measuring it where it happens to be 165 lbs. It would be roughly 28 lbs on the surface of the Moon. No matter where he is when he steps on the scale, whatever the scale reads, that's his WEIGHT.
Great video! I have these talks with my two boys, all the time!👍😉
"There is an art to flying, or rather a knack. The knack lies in learning how to throw yourself at the ground and miss." -- Hitchhiker's Guide to the Galaxy
Old Timey Scientist "Look at my wonderful invention, it tells you how much things weigh"
The Science A (Pushing and pulling mannicly on spring watching dial)
Old TS (Takes back scale, locks in timeless vacuum chamber) "You're using it wrong!"
The SA "But...... It was telling me something"
I dunno why this episode made me laugh so hard, maybe I'm weigh too much of a nerd.
I’ve had to explain this to my students so many times and they think I’m crazy because no one else explains it this way.
Surprisingly I have always explained how bathroom scales work the same way. Nice video.
All the science stuff and all was really cool, but then I saw the TMNT shirt and I had tu sub. Great content!
I will agree, you can’t feel “weight” what you feel is the normal force for the required acceleration. As in an aircraft, in a pull-up, “pulling gs” what your are feeling is the normal force, being provided by the seat of the aircraft, to accelerate you. Hence, if you are sitting on a scale in the aircraft you will see the required force to accelerate you with the aircrafts changing flight path (velocity)
I have to disagree with you! If some fat ass (correction - "massive") person stands on my foot, I definitely feel his/her weight.
@@AFmedic what you are feeling is the floor not only accelerating your mass, but the mass of the “fat ass”. The force is transmitted from the floor, thru your foot, to the fat ass.
Actually you do feel weight, because technically "weight" is a force. What people colloquially refer to as "weight" is actually "mass".
@@antred11 It depends on how you define weight. Most people learn that weight is the pull of gravity, and in that case, you CANNOT feel your weight. You cannot feel the difference between accelerating through deep space at 9.8 m/s^2, and standing stationary in Earth's gravitational field of 9.8 N/kg. You feel the constraint force that keep you at rest in your immediate environment, and you instinctively assume the constraint force opposes your weight.
If instead, you define weight as your reaction to a constraint force, then indeed you do feel it. In any case, you ultimately feel constraint forces, and you cannot feel the force of gravity.
I've taken many physics courses in my engineering education and never had an issue with the idea of weight. We always calculated and described weight as the product of mass in the presence of a gravitational field. Weight is an object's mass multiplied by acceleration of gravity. Some of this seems to muddy that concept.
Sounds like you have a really great handle on what weight is 👍. This is _not_ common.
If you didn't notice that this channel is for people to learn not for knowledgeable people to humbly brag about how smart they already are so congrats you got an education to come to RUclips a flaunt.
Newtonian physics vs General Relativity. He is basically showing how acceleration is the same as gravity in the elevator experiment. The scale measure a compression force of the feet and the base. Manufacturers of scales use a standard weight. There is a actual weight that is measured to be exactly 1 pound or 1KG. Then the manufacturer uses that to calibrate the scale so that when we stand on it with the expected 1G of earth we can calculate our weight. But it’s not measuring weight, but the compression of the force of gravity of earth and the gravity of our bodies compressing the scale. The scale is then designed to represent that force as weight based on that standard weight it was calibrated to.
wow i just found you through your other channel where you talked about autism, i was diagnosed later than usual as well and it was tough. Seeing what you have achieved here and your great communication skills it gives me some hope :)
Being as functional as I am today took a lifetime of work, practice, and self training.
Another fantastic video ! I ❤️the science and I ❤️ the humor!
Thanks for the video.
I read the title.
And immediately thought: "To prove Einstein right."
haven't seen the video yet.
I could hear you talking with your wife
"I need to push a scale on your back."
"Why?" [Inquisitive eyebrow raised]
"Because SCIENCE! But in all actuality, I want to explain to the Crazies the difference of "weight" and push force."
"OK, just don't get my face, I haven't done my makeup yet."
That's pretty spot on actually 😂
Your videos are awesome.
Thank you very much. Now I’m going to put my scale in a swimming pool and see what happens next.
Boom! Kicking it up a notch...
Make sure it's an analog one! (Honestly, I had planned to do this for the buoyancy part of the video, but ran out of time.)
That's the science spirit right here !
I really like your style of teaching. I have watched almost all of your videos. I really used to like the style of the one which you made a year back around or so would like to see more of it.
There seem to be at least three different definitions of the word "weight". 1) Mass m in kg (as understood by most people and intended to be measured by the bathroom scales) 2) Force of gravity, mg in Newtons, as defined by US/EU textbooks 3) Force applied to a support, m(g+p) in Newtons, as defined by some Eastern European textbooks.
My girlfriend has several definitions of "weight" also. I agree with all of them.
If you turn the scale upside down, you can measure the force of the Earth on you (unsurprisingly identical to your force on Earth)
you don't exert a force on the earth at all, because then they would cancel each other out - "gravity" that causes your weight is caused by your acceleration from the earth pushing you up to stop you from falling
@@incription Ever heard of Newton 3rd law ?
@@YvesDautremay newton's third law only holds in euclidean space, but because of gravity, it's doesn't, right?
I love to watch this guy arguing with himself!!
Dude you're so good at getting angry with your nerd clone, lmao. I bet a lot of work went into figuring out how to time that just right, with the i-i-i -it, and head shaking. Or maybe your just a brilliant genius who had an innate sense for how to deal with nerd clone.
I'd say the snow vs slush thing is much more about density than bouyancy: A shovel full of snow is going to be less dense and contain less mass than a shovel full of slush.
Yep. A very weird, misleading example. The point about bouyancy effect would be that shovelling 1 kg of snow would be indetectibly (to human senses) easier than shovelling 1kg of slush, as the displaced air due to the larger volume of 1kg of snow vs 1 kg of slush would be provide some tiny bouyancy effect in the vertical direction. In reality the greater wind resistance of moving a 1kg mass of snow vs a 1kg mass of slush would probably exceed the bouyancy effect. I'd say "leave it to 'The Science Asylum' to calculate if the wind resistance effect would be > or < the bouyacy effect in practice, but I doubt they would get the calculations correct...
PROFESSOR!! I shouldn't say your last name here!! You inspired me with your physics 1 class and I passed the Civil PE in Water Resources & Environmental this past October. I think of you fondly, and often. The history of physics is still the best thing I've ever learned and I have you to thank for my career path. I found this channel while looking for you so that I might thank you.
I'm so glad to hear you're doing well! Thanks for looking me up. It's always nice to hear from past students.
yes i was just going to grab my bathroom scale to measure my elevators acceleration
You have an elevator?
So Douglas Adams was right. Flying is just falling down and missing the ground.
That's orbit.
she: i only date bad boys
nick lucid: i use bathroom scales on elevators
she: OMG let's passionately hug ;)
this is the first vid I see and subbed immediately. Very interesting and very well explained, also it's refreshing to change perspective on the mundane.
You are the prime exmaple of the person people refer to "You must be fun at parties".
And i love it!
I've had people say that to me before.
That goofy squirrel has taught me more about physics than school did.
Sorry about your school...
I would have been even happier if you had included the word "mass" at least once.
A lot of confusion between mass and weight going around as I recall.
1:14 but he never included word 'inertia'
@@Thrill98 Yeah, and again at 1:52.
I guess what I missed was a sentence clearly stating the difference or the relation between mass and weight.
This video wasn't about mass, so mentioning it would have been distracting I think.
@@ScienceAsylum Well, don't worry then, I will look it up in an older video.😁
I clarified the proper physics definitions in the pinned comment.
I wish I could double like this video. I never knew that the orbit of the space station gave the appearance of weightlessness. It makes sense. They’re in an almost endless fall.
best physics guy out there! Continue with the good job!
Great presentation, brings back memories of my youth when I was really into technical things.
2:50 They are not flying. They are just falling with style.
Nick, you're very informative and entertaining to watch. Thank you
I don't feel I need to for the simple fact that you did it for us. Thank you sir, great content
They measure force put into them.
You can make make that number bigger by just pressing it stronger
I believe that you may be confusing the terms weight and mass.
Mass is the measure of how much matter makes up an object. Usually measured in grams. (g)
Weight is a measurement an object's mass multiplied by the gravity/acceleration (m/s2) acting upon that object. Usually measured in Newtons. (N) or (g*m/s2)
Since most Americans measure their weight in pounds, which have the same type of units as newtons, (mass x distance / time squared) and pounds use earths gravity as a constant of 1. It is very easy to confuse the two very different types of measurements. The average bathroom scale is doing this calculation for you and when you take the scale in the elevator you are changing your acceleration and thus changing the gravity constant that the scale needs to give you your appropriate weight.
still not weight
See the pinned comment.
Well i would put it like this - astronauts in LEO are weightless, but aren't massless
There are essentially only 2 forces: PUSH & PULL (even the strong & weak forces) are essentially push (repulsion) / pull (attraction).
A force can be described as the influence that cab change the motion of an object. It has both magnitude & direction.
Mass = quantity of matter ( = both potential AND kinetic energy)
F = ma DOES NOT EQUAL F = Gm1m2/r^2
F=ma = PUSH
F=Gm1m2/r^2 = PULL
LET:
speed of light = 3e8 m/s
Plank length (PL) = 1.616e-35m
Plank mass (PM) = 2.18e-8 kg
Smallest possible object is one with plank length = 1.616e-35 m & plank mass = 2.18e-8 kg
G = 6.67e-11 m^3/(kg.s^2)
To solve: G = c^2 x PL / PM
Check units = c^2 = m^2/s^2; PL = m, PM = kg
G = m^3 / (s^2.kg) = c^2 = 9e16 PL/PM = 7.43e-28
It is known that 2 objects each with a given mass will attract one another.
So, G. the gravitational constant, describes the force of attraction the smallest possible object in the universe exerts.
If you assume all objects are bound to each other then you may even call it a torque.
in wikipedia article "mass versus weight! we can find "The mass of an object is a measure of the object’s inertial property, or the amount of matter it contains. The weight of an object is a measure of the force exerted on the object by gravity, or the force needed to support it. " that are the correct definitions
🤔 Interesting. So wikipedia lists both the physics and the engineering definitions?
Whenever I travel in an elevator while standing on bathroom scales I'm always holding on to a bunch of six helium-filled balloons. It's a quirk of mine. Whatcha gotta say about that effect, mister? Huh, smarty-pants?
thats a good one. it would still be push force measured I guess, with the balloons affecting your weight and your mass staying the same (unless you added the mass to your body)
Dr Nick, you're one of the best at explaining Physics. Would you consider making a series of video about Loop Quantum Gravity? Something about Loops as solution to the Wheeler-Devitt equation, Spin Networks, Volume as a quantum property of a node and Area as quantum property of a link, the emergence of "Space" from a Spin Network, Spin Foam and the emergence of "Time" from the evolution of a Spin Network. LQG is a very neglected topic, it's very hard to find good material...