@@yoprofmatt Too many comments often compliment the instructors. My problem is why do we teach Newtonian physics when Einstein gave us general relativity. I agree in that inertial is a non accelerating frame of reference, but wouldn't Einstein disagree with Newton with resect to gravity and being in an inertial frame of reference? BTW, thanks for your very good presentation.
@@davidmudry5622I’m late to this but let me answer. Newtonian physics is perfectly applicable until huge quantities in space. For the average student it’s all they’ll need because most students who take physics in high school don’t actually become physicists. Secondly, newtons laws build good mathematical instincts.
@@allensnea9335 Newton satisfies the math, but it does not satisfy the physical reality. NIST WTC FAQ 31 answer from NIST "Since the stories below the level of collapse initiation provided little resistance the building section above came down accelerating essentially in free fall." Einstein, "free fall is the equivalent to floating, doing absolutely nothing, and being weightless in deep space." Two spaceships are heading towards each other. The radar on each ship indicates the other ship is accelerating towards it. However only one of the ships is actually accelerating. The accelerating ship is the entire Saturn V Rocket, with lots of inertia. The non accelerating ship is just the tiny Apollo space capsule, with very little inertia. The crew in the one accelerating will all be sitting in chairs with coffee in cups sitting on a table, just like here on earth. In the other ship the crew will be floating around weightless, just like falling in free fall. There will be a huge collision when the huge rocket hits the tiny capsule. But wait a minute, if the huge rocket only started to accelerate from a distance of 12 feet away, like the distance separating the north tower's 95 lower floors from the falling upper 12 floors, then only a relatively slight bump would occur.
During covid I'm doing my physics degree by distance learning. Whilst reading through the mounds of textbooks, its sometimes good to break it up with a nice concise lecture like this. Can help you visualise a lot easier. Thank you! I will be sure to check out your other videos.
sir a lots of love from pakistan .... I am learning physics from you . This is the luck of new generation that teacher like you is availble on you tube... sir lots of love and happiness for you...
QUESTION........Do ALL inertial frames of reference have the same physics??????? If i do a physics experiment in one inertial frame of reference will i get the SAME results in ALL inertial frames of reference??????????? If you get different results in each inertial frame of reference then how many DIFFERENT TYPES of inertial frames are there???????????????
Professor..! You are amazing. Thanks for this awesome explanation. I'm just wondering how the writing glass works both ways. Please help us understanding earth as an inertial frame with greater details.
Hi Subhasis, Thanks, I appreciate the feedback. Learning Glass explained here: www.learning.glass As for inertial frames, the earth is not technically an inertial frame, since it (and us) are accelerating. But it's pretty close, so for most lab experiments, you can consider it an inertial frame. Hope this helps. Cheers, Dr. A
SIR why we are in a rotating object like a satelite , then the tangetial velocity is constan. then can i consider it as an intertial frame of reference even though there is a centrepetal accereation. IAM A REAL FAN OF YOUR LECTURS. PROBABLY THE BEST. THE HIGHEST STANDARD. BEST SIR YOU REALLY HELPED ME WITH ,MY MECHANICS A ALOT.----- RESPECT FROM INDIA
@@yoprofmattYou forgot to mention that defining inertial frame of refrrence is the main problem in SR and GR, which plagues the theory and makes it unable to resolve twins paradox, which Einstein himself acknowledged.
May I suggest that you also define "frame" which admittedly and unfortunately no one does but is important. My definition of a frame is "no relative motion in space and time". Thus in my frame (say a room) there should be no relative motion between me and my spatial environment plus the time in all the clocks in my environment be in synch. A NOT my fame frame even if inertial, will be moving relative to me in space AND time since its clocks will show increasingly lagging time relative to mine and the time will also be directionally desynchronized with trailing clock being advanced proportional to distance and speed of relative motion. Both frames may be inertial yet one is my frame and the other not. The differentiation can be made by relative motion in space and time.
can u please tell me why air-planes are not affected when travelling from equator to north or south : their route will remain straight with their speed and not diagonal ?
mz, Two thoughts: 1) The atmosphere also rotates with the earth. 2) All objects that move on the earth are subject to the "Coriolis Force" which is a fictional force but makes it seem like you're getting push to the left or right (depending on which hemisphere you're in). In reality, you are trying to travel in a straight line (Newton's first law), and the earth is changing its directory underneath you! Thanks for the comment, and keep up with the physics! You might also like my new website: www.universityphysics.education Cheers, Dr. A
A falling man is an inertial frame of reference, as is the space station, or the planet Earth itself. If you are floating thru space, you would be too. However if you are planted in anyway to the planet, it is accelerating towards you at 9.8m/s and thus you are accelerating too (in the opposite direction.) Your position doesn’t change, but that is due to the bending of space around you due to the mass of the planet.
all I can think ab is whether he's writing backwards or if the camera is flipped but if the camera was flipped then his class wouldn't be able to see the words so... he's writing backwards......????
Sorry if my question is a little bit funny, im just curious, Let say that we can freeze every particle in the whole univerese on its potition,how long is the gap beetween "one frame" to the next "frame"?. What i mean by "frame" is the arangement of all particle at one point in time.
Indeed correct! Of course you can flip it in post, but you can also flip it live with a mirror, or a special electronics box, or its even built in to certain cameras. More info here: www.learning.glass Cheers, Dr. A
But how did students follow the lecture if it was written on glass from the other side? Or is this the kind of mirror which is transparent from one side and camera is on that side? Lmao that's brilliant.
If an airplane is turning in a circle at a constant altitude with respect to the ground, is it in an inertial frame? If not, where is the center of it's turn with respect to an observer not standing on the ground?
So if I'm in a vehicle with a large open window at the back travelling at constant velocity and I throw a ball up into the air as the vehicle accelerates would the ball remain still relative to the Earth and so 'fall out of the car'? I'm struggling to get my head around this so i hope my question makes sense! Thanks
I think u should close the window first. Because the ball would maintain the speed of that instant when it was thrown up and u along with the car would achieve some higher speed in that small time interval due to the acceleration of the car, so the ball can hit on ur head and bounce off through that open window. I hope you don't wanna loose your ball.
The inertial Frame based on the seated person on a moving planet. The frame of reference is related only to everything on earth because the reference frame is only to that environment? The frame relevant to the moon is different because the moon is not part of the frame under discussion. Is that right?
The professor is wrong. The equivalence principle (made famous by Einstein) says that gravity and acceleration are indistinguishable. Thus, any time your scale reads non-zero you are in an accelerating frame. Only observers who are in free fall are in inertial frames.
Hamza younis, Glad to hear it. Thanks for the comment, and keep up with the physics! You might also like my new website: www.universityphysics.education Cheers, Dr. A
I am confused and no one will help me. (1) I am told there is only ONE type of inertial frame of reference. (2) meaning if i do a physics experiment in ANY inertial frame i will get the SAME RESULTS no matter what inertial frame i am in (3) Disregarding earth spinning and angular momentum (acceleration) I am told earth is an inertial frame. (4) I am told being in outer space at a constant velocity is an inertial frame. OK THESE STATEMENTS CONTRADICT ONE ANOTHER !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Because if that were ALL true then that would mean that i could do physics experiments in outer space (at a constant velocity) and then do the SAME PHYSICS EXPERIMENT on earth and get the SAME RESULTS. But that IS NOT TRUE. THAT IS A LIE. If i am in outer space(at constant velocity) and i hold a ball out and let go of the ball with out throwing it or pushing it in any direction the ball will just float there. But on earth if i do the SAME experiment the ball will fall to the ground. So there are (1) more than one TYPE of inertial frames of reference OR (2) earth is NOT an inertial frame of reference. SO WHICH IS IT !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Why wont any one answer me???????
Standing on earth means you are constatly accelrating at 1G upwards. Saying that it is inertial frame of reference is not correct. Its newtonian inertial but not relativistic. Maybe i am wrong...
QUESTION............When someone says a point in space.......meaning having no real volume. Does that really mean it has NO volume or does it mean the volume is smaller than a plank length(volume) and so it is there but it is an undefined volume of space ???????????????????
Wow, outstanding question. It's a very classical definition saying "a point in space" which means zero volume, but of course you're right, we should really be talking about a Planck volume. That is the smallest volume you could ever hope to measure. Which, of course, is pretty darn small. Wikipedia has a great entry on Planck Length. Check it out. Cheers, Dr. A
Your answer to the girl was not clear. I would have told her that she was not in an inertial frame of reference unless she was in a state of freefall. One way to test if you are in an inertial frame is to drop a ball, and if it stays where it is, you are in an inertial frame.
Excellent comment. Here's a very good explanation about this: www.physicsforums.com/threads/is-a-falling-elevator-a-valid-inertial-frame.331302/ Cheers, Dr. A
But the earth spins at a constant velocity. Doesn't that mean that we are in an inertial frame. The earth rotational acceleration must be equal to 0 or extremely close to 0. Because if it wasn't, would that make the days shorter as time passes?
+Manuel Rojas Velocity is a vector, not only a number. The magnitude of our velocity is constant, but the direction of our velocity is always changing, because we are moving in a circle. Thus, we have an acceleration toward the center of the Earth at all times.
+Alex Glisson Alex is correct. The earth spinning means we have a constant "speed" (the magnitude of velocity) but the direction is always changing. Since acceleration is a change in velocity over time, and your velocity right now is changing (specifically, you are moving in a circle, thus the direction of your velocity is changing), you are accelerating. For circular motion, this is what we call centripetal acceleration. Cheers, Dr. A
Can inertial frames even exist? If we take a maximally macro view of the cosmos everything is accelerating away from each other at an increasing rate. Therefore a frame can only be inertial in the micro. Is a frame truly inertial if you ignore variables?
Which I think constantly shifts? Just a doubt, acceleration of individual masses also causes the location of COM to accelerate right, as every mass unit has a different acceleration?
There is no one correct frame of reference, so to say the entire universe is expanding is irrelevant. On the other hand it could be argued that everything is motionless relative to itself , so EVERYTHING is a inertial frame of reference i would think
Acceleration= change in velocity upon time taken. since there is no change in speed the time required for revolution remains same. Hence same no. of days in a year 365.25 but we consider 365 days and add an extra day every leap year because 0.25 days ×4 = 1 day. But since direction of earth is changing continuously so velocity changes continuously Hence earth is accelerating.(Velocity = Displacement/Time). Hope this helps.
Rukul Singh you are telling that there is no change in the speed, that means it is in constant velocity, this means that earth should be an inertial frame is refrence, which means wrong!!
Technically, the spin of the earth is slowing down due to the gravitational force of the moon. A day used to be 16h a few million years ago. The mass of the sun is getting lower too, so the earth is getting further away as gravitation decreases. If earths tangential speed stays the same, a year will become longer, but days will become longer too so it will take "a while" before a year is more than 365 days. But both of the accelerations referred to in this video are radial. Since both the earth and a point on the surface of the earth are moving in a circular motion, they have radial acceleration towards their centers of rotation, the sun and the absolute center of earth's core respectively. And since a point on earth can be towards or opposite the sun with opposite velocities relative to earths orbit around the sun, the radial acceleration will fluctuate. But physics is about simplifying problems into practical models so we ignore these relatively insignificant accelerations. If this bothers you, you can always become a mathematician :)
QUESTION...…...If I am in a space ship in outer space with no planets or any mass near the ship and I am moving at a CONSTANT speed then I am in an inertial frame of reference. I can prove it cause when I put 100 N of mass on a scale it weighs ZERO. Also if I hold a ball in the air and drop it the ball does NOTHING. The ball floats and stays where it is relative to me and the ship. If I am in a space ship accelerating at 1g (9.8m/sec2) then I can prove I am in an accelerated frame of reference. Because if I use a scale and weigh something a 100 N it will weigh a 100 N due to the fictitious force produced by acceleration. Also if I drop a ball in the air, on the accelerating spaceship, then the ball will fall in the opposite direction of the acceleration due to a fictitious force. So why would I not say that earth is an accelerating frame of reference??????????????????? On earth a 100 N of mass weighs a 100 N due to a fictitious force created by warped spacetime. Sounds like an accelerated frame of reference to me. Fictitious forces are associated with accelerated frames of reference and gravity is a fictitious force. Also when I hold a ball out in the air the ball falls in the opposite direction of the acceleration. It does not float there and not move like in outer space at a constant velocity. SOUNDS TO ME LIKE EARTH IS A NON INERTIAL FRAME OF REFERENCE?????????????????????????????????????????? You know if you and your students and your classroom where on a spaceship accelerating at 1g (9.8m/sec2) and all the windows were blacked out. And a student said we are accelerating. Would you answer back and say sarcastically...……….."Do we look like we are accelerating?". Would you be the crazy one or the student in that scenario. Because the spaceship going 1g sounds just like earth to me. ALL THE PHYSICS LAWS seem to be the same weather you are on earth or in a spaceship going at 1g. My final question is...….If the 1g accelerating spaceship is definitely in an accelerated frame of reference then how can ALL the physics laws be the same with earth if earth is in an inertial frame of reference????????????????
JBSC, Great comment, thanks. Very valuable insight here. It's true that technically gravity has been replaced by warped space-time in general relativity. With Newton's Laws we approximate inertial frames because they are VERY close to giving us the correct answers, thus is valuable for predictions here on Earth. Nice work! You might also like my new website: www.universityphysics.education Cheers, Dr. A
Michael Rayo, Yep, safety first. Not writing backwards (I'm not that talented). The board is called Learning Glass. You can check it out at www.learning.glass Cheers, Dr. Strange
Drawing with a paint pen backwards to avoid blocking your students from reading your writing? Impressive. Plus the genius it takes to record your lectures these days? Your students aren't doing sentences in detention, that's for sure.
Isnt there an additional force other than the m*g and the scale? The force of inertia opposing the g acceleration? When i accelerate my car , a force pushes me back ,opposing the acceleration. Doesnt this force have to be taken in consideration? Sorry, it was a long time ago when i went to school.
Time ic certainly independent of reference frame. A spinning cd disk always take the same time for one rotation whether it is moving along axis of rotation or not. vixra.org/abs/1807.0027
Thanks for the comment, but I don't agree. Time is relative, and as Einstein said, "moving clocks run slow." Which means that if you send a clock on a rocket at very high speed, it will run slow (as viewed from earth). This simple statement leads to some fascinating (and mind-bending) results, such as the twin paradox: Most people have heard of this, and know that if you separate twin brother and sister at birth, and send the girl on a very fast space ship for a while, when she returns she will be younger than the boy. (Since "moving clocks run slow".) So what's the paradox? The paradox is that if time is relative, then the girl on the spaceship looks back at earth and says that the boy's clock is running slow, therefore he must be younger when she returns. Hmmm...chew on that for a bit. Cheers, Dr. A
Paradox is a result of inconsistency in theory. In this case, Special Relativity. This is why Einstein's theory never becomes a physics law. It remains as a theory because it can not be verify. Apparently you have not read this paper yet. vixra.org/abs/1807.0027
@@muhammadosama3295 technically speaking Earth is not a inertial reference frame. But it's approximately inertial because centripetal acceleration is so small. And you can formulate Newton laws for non inertial reference frame by adding so called fictitious forces. So physical laws can be apply to non inertial reference frame
I say your wrong. I say the scale in an elevator has to read ZERO newtons for the person to be in an inertial frame of reference. If you disagree then EXPLAIN why when i am in outer space moving at a constant velocity and am in an inertial frame of reference and i weigh myself i weigh ZERO newtons????? If the scale reads 100N then i am in the same frame of reference as the earth. AND I SAY THE EARTH IS IN AN ACCELERATED FRAME OF REFERENCE. Why am i wrong???????????????????
CHALLANGE TO ANYONE WHO thinks earth is an inertial frame and "free falling" is an accelerated frame of reference. THEN PROVE IT BY ANSWERING MY QUESTION !!!!!!!!!! Let us say you are in an elevator WITH NO WINDOWS on the moon so there is no air. And the rope holding the elevator breaks on the 500th floor and you and the elevator starts "free falling". And lets say i am in a space ship in outer space moving at constant velocity. WE BOTH WOULD SAY I AM IN AN INERTIAL FRAME. Now you say "free falling" is an accelerated frame of reference. So YOU ARE SAYING we would be in DIFFERENT frames of reference......you in an accelerated frame and me in an inertial frame. SO YOU SHOULD BE ABLE TO PROVE IT EXPERIMENTALLY...RIGHT??????????????????????? Cause if we do identical physics experiments there should be at least ONE experiment where we get different results.....right. WE BOTH AGREE WITH THAT RIGHT?????????????? So tell me what experiment would you do to PROVE you were in an accelerated frame of reference while you are "free falling" inside your elevator???????????? If you can NOT think of an experiment that would give us different results then you must admit that "free fall" is an inertial frame because WE BOTH AGREE THAT me in a space ship in outer space moving at constant velocity is AN INTERTIAL FRAME. And guess what. If you .......while in your "free falling" elevator would hold a ball out and let go of the ball with out applying any force to the ball. Guess what the ball will just float and not move relative to you. Just like it would for me in my space ship. So that would be the same result. What experiment will you tell me about that gives different results???????????
John, Excellent, excellent comment. I especially love the caps. What you are describing, of course, is exactly the thought process that Einstein went through when he developed his general theory of relativity. Which is, of course, a much more exact theory of gravitation, but is a bit beyond the class that I'm teaching here. I'll try to add it in a future series. Cheers, Dr. A
@@yoprofmatt ....OK so i am right. I mean you agree...right. I thought i was going crazy. I was just watching an "entertainment" type physics video about frames of reference and said earth was an accelerated frame. So everyone said i was crazy. So i said don't all inertial frames have the same physics and they said yeah. So i said to them why on earth does a ball not float when i let go of it like in an inertial frame. They said when you let go of the ball it falls cause then it is in an accelerated frame. So i cut and pasted what Einstein said about "free failing" being inertial and earth being equivalence to an accelerated frame. They said Einstein was wrong. So that is when i went crazy and posted my challenge on a bunch of physics videos labeled frames of reference. Anyways thanks for your time i will have to check out some of your videos
My book confuses me because on the elevator problem it says "if the elevator accelerates then it is NOT an inertial frame"...then later a problem asks "what does the scale say if the elevator accelerates upward..." Yeah that's confusing.
Q1: Inertial frame moves at constant velocity... But with respect to what? Another inertial frame? Q2: Inertial frame does not have acceleration with respect to what? Another inertial frame? Q3: You are saying that the elevator is not a inertial frame because your weight is more than 100N. Where did you measure your weight at the first time? On earth? Are you not already considering earth to be an inertial frame then? It seems that your logic has a circular fallacy.
Some years ago, the physics prof. in the physics classical mechanics course I was enrolled in asked the class: What is an inertial reference frame? The class was comprised of about 100 or so physics and engineering majors. But nobody had an answer. The prof. waited... crickets. (This was before the advent of laptops in the classroom, but even so, I am not sure that would have helped, since, for example, the current Wikipedia definition is wrong.) Still, none of the physics and engineering students had an answer, presumably, because they understood that stating that it is a reference frame with constant velocity begs the question constant with respect to what? Finally, the prof. gave his answer. An inertial reference frame, according to the prof., is a reference frame in which Newton's Laws are valid.
@@larrymusa6717My humble request to you... You can watch my video that is given in the link above and see if you get a satisfactory answer to your question or not...
Edventure - Unfortunately, your definition is garbage, but you get partial credit for understanding that defining an inertial frame as a frame that is not accelerating is also garbage. I gave you the definition: An inertial frame is one in which Newton's Laws are valid.
Plain wrong. Velocity relative to WHAT? Acceleration relative to WHAT? Its not the rotation, which makes the lab-frame "non-inertial". Its gravity. Your explanation of "inertiality" with the help of "scale" and "weight" is completely misleading/wrong. If at all, "inertiality" could be substituted by "weightlesness". Like on the ISS ...
Raphael Johnson, Tremendous! That's yuge. Thanks for the comment, and keep up with the physics! You might also like my new website: www.universityphysics.education Cheers, Dr. A
"you don't look like you're accelerating at negative g" LOL made my morning.
Bruh, Benedict Crumplesnitch good at physics
😂😂😂😂😂exactly what I thought
Bruhh , i have came here to learn but this comment😆😆😆😆😆😆
The tone of your voice is excellent for teaching. It's very calming. I appreciate it, sir - thanks a lot!
Don't hear that too often. You must have a good equalizer. Keep up with the physics!
Cheers,
Dr. A
@@yoprofmatt Too many comments often compliment the instructors. My problem is why do we teach Newtonian physics when Einstein gave us general relativity. I agree in that inertial is a non accelerating frame of reference, but wouldn't Einstein disagree with Newton with resect to gravity and being in an inertial frame of reference? BTW, thanks for your very good presentation.
@@davidmudry5622I’m late to this but let me answer. Newtonian physics is perfectly applicable until huge quantities in space. For the average student it’s all they’ll need because most students who take physics in high school don’t actually become physicists. Secondly, newtons laws build good mathematical instincts.
@@allensnea9335 Newton satisfies the math, but it does not satisfy the physical reality.
NIST WTC FAQ 31 answer from NIST "Since the stories below the level of collapse initiation provided little resistance the building section above came down accelerating essentially in free fall." Einstein, "free fall is the equivalent to floating, doing absolutely nothing, and being weightless in deep space."
Two spaceships are heading towards each other. The radar on each ship indicates the other ship is accelerating towards it. However only one of the ships is actually accelerating. The accelerating ship is the entire Saturn V Rocket, with lots of inertia. The non accelerating ship is just the tiny Apollo space capsule, with very little inertia. The crew in the one accelerating will all be sitting in chairs with coffee in cups sitting on a table, just like here on earth. In the other ship the crew will be floating around weightless, just like falling in free fall. There will be a huge collision when the huge rocket hits the tiny capsule. But wait a minute, if the huge rocket only started to accelerate from a distance of 12 feet away, like the distance separating the north tower's 95 lower floors from the falling upper 12 floors, then only a relatively slight bump would occur.
During covid I'm doing my physics degree by distance learning. Whilst reading through the mounds of textbooks, its sometimes good to break it up with a nice concise lecture like this. Can help you visualise a lot easier. Thank you! I will be sure to check out your other videos.
so it means it should be in an equilibrium state to be in an inertial frame
oh my goodness. I just watched so many videos and read my text. I thought I was getting it but this explained it SUPER clearly! Thank you!
in the 20 minutes i shouldve been using to study im still trying to figure out how that board works...
😂😂😂😢same
video mirrored
i watched alot of videos but this is the best one
Have you ever worked in the military where you had to write backwards(submarine, aircraft controller)?
half way through the video i realized he is writing backwards. Awesome.
No. The video is flipped.
@@user-xm7vu9ql8n yes I know. I have been waiting for this reply for 3 long years. at last, it is fulfilled and now I can rest.
@@TheAnkan001 🤣🤣🤣 10 likes, 3 years, and no one got your soul to finally rest. It’s been an honor!!
Yes, so long traveller. Here I rest.
You are really talented ,sir, I have your video, you have done/teach this topic comprehensively
sir a lots of love from pakistan .... I am learning physics from you . This is the luck of new generation that teacher like you is availble on you tube... sir lots of love and happiness for you...
You are a fabulous teacher... thanks man
nicely explained
great learning glass created
👍👍👍👌
Everybody talking about the mirror writing technique!
Wonderful lecturer that makes physics fun and understandable !!!
Wow that's pretty impressive, writing backwards 👍
+xuan truong The video is mirrored... duh. ;p
Blackmagicfuckery
It is called the lightboard! ;)
@@IdiotBoxGuy so the students are viewing the board backwards?
QUESTION........Do ALL inertial frames of reference have the same physics??????? If i do a physics experiment in one inertial frame of reference will i get the SAME results in ALL inertial frames of reference??????????? If you get different results in each inertial frame of reference then how many DIFFERENT TYPES of inertial frames are there???????????????
great work perfect explaination and illustration. thanks sir.
Great explanation and example Prof Anderson.... Thank you for these excellent Video.... 👍👍
You're very welcome. Keep up with the physics!
Cheers,
Dr. A
Hey, could u explain why we subtracted the real weight and weight from the scale?
Very good explanation.Thanks a lot sir.
So now why would we need to know if something is in an inertial frame? I wish I could've asked him that question.
BEAUTIFUL explanation.
+Kervin Ebanks
Thanks Kervin, glad you enjoyed it.
Cheers, Dr. A
Professor..! You are amazing. Thanks for this awesome explanation. I'm just wondering how the writing glass works both ways. Please help us understanding earth as an inertial frame with greater details.
Hi Subhasis,
Thanks, I appreciate the feedback.
Learning Glass explained here: www.learning.glass
As for inertial frames, the earth is not technically an inertial frame, since it (and us) are accelerating. But it's pretty close, so for most lab experiments, you can consider it an inertial frame. Hope this helps.
Cheers,
Dr. A
Thanks Professor Anderson.
Fantastic explanation...
SIR why we are in a rotating object like a satelite , then the tangetial velocity is constan. then can i consider it as an intertial frame of reference even though there is a centrepetal accereation. IAM A REAL FAN OF YOUR LECTURS. PROBABLY THE BEST. THE HIGHEST STANDARD. BEST SIR YOU REALLY HELPED ME WITH ,MY MECHANICS A ALOT.----- RESPECT FROM INDIA
Hello sir
I want to ask you a question that can an object have an acceleration but no net force?
This was so helpful. Thank you! :)
You are very welcome. Keep up with the physics.
Cheers,
Dr. A
there must be some way to filter out the squeak lol (lowpass filter perhaps?)
Amazing explanation! Thank you professor! 🙏🏼❤️
Hi Manasee,
Thanks for the feedback. Hope you're enjoying physics.
Cheers, Dr. A
@@yoprofmattYou forgot to mention that defining inertial frame of refrrence is the main problem in SR and GR, which plagues the theory and makes it unable to resolve twins paradox, which Einstein himself acknowledged.
bruh i thought he was a master of writing in reverse
The Earth Centered Inertial frame called and said he felt offended
May I suggest that you also define "frame" which admittedly and unfortunately no one does but is important.
My definition of a frame is "no relative motion in space and time". Thus in my frame (say a room) there should be no relative motion between me and my spatial environment plus the time in all the clocks in my environment be in synch.
A NOT my fame frame even if inertial, will be moving relative to me in space AND time since its clocks will show increasingly lagging time relative to mine and the time will also be directionally desynchronized with trailing clock being advanced proportional to distance and speed of relative motion.
Both frames may be inertial yet one is my frame and the other not. The differentiation can be made by relative motion in space and time.
can u please tell me why air-planes are not affected when travelling from equator to north or south : their route will remain straight with their speed and not diagonal ?
mz,
Two thoughts:
1) The atmosphere also rotates with the earth.
2) All objects that move on the earth are subject to the "Coriolis Force" which is a fictional force but makes it seem like you're getting push to the left or right (depending on which hemisphere you're in). In reality, you are trying to travel in a straight line (Newton's first law), and the earth is changing its directory underneath you!
Thanks for the comment, and keep up with the physics!
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A
is elevator an inertial frame of reference in this example ?
A falling man is an inertial frame of reference, as is the space station, or the planet Earth itself. If you are floating thru space, you would be too. However if you are planted in anyway to the planet, it is accelerating towards you at 9.8m/s and thus you are accelerating too (in the opposite direction.) Your position doesn’t change, but that is due to the bending of space around you due to the mass of the planet.
excellent explanation!
Thanks umpar, glad you found it useful.
Cheers, Dr A
all I can think ab is whether he's writing backwards or if the camera is flipped but if the camera was flipped then his class wouldn't be able to see the words so... he's writing backwards......????
Sorry if my question is a little bit funny, im just curious, Let say that we can freeze every particle in the whole univerese on its potition,how long is the gap beetween "one frame" to the next "frame"?. What i mean by "frame" is the arangement of all particle at one point in time.
Nas,
Wonderful question that I have absolutely no idea how to answer. But keep asking, and keep up with the physics!
Cheers,
Dr. A
how the hell your board works .....are u writing mirror wise......
he's writing on glass and the camera footage is flipped after shooting.
Indeed correct! Of course you can flip it in post, but you can also flip it live with a mirror, or a special electronics box, or its even built in to certain cameras. More info here: www.learning.glass
Cheers,
Dr. A
But how did students follow the lecture if it was written on glass from the other side? Or is this the kind of mirror which is transparent from one side and camera is on that side? Lmao that's brilliant.
thank you so much sir!
someone post his office hours, please.
When the lecture is beautiful 😂😂🙏🙏
thank you
Superb... finally understood. 😊
Outstanding.
Cheers,
Dr. A
If an airplane is turning in a circle at a constant altitude with respect to the ground, is it in an inertial frame? If not, where is the center of it's turn with respect to an observer not standing on the ground?
Can we find inertial reference in the universe?
So if I'm in a vehicle with a large open window at the back travelling at constant velocity and I throw a ball up into the air as the vehicle accelerates would the ball remain still relative to the Earth and so 'fall out of the car'? I'm struggling to get my head around this so i hope my question makes sense! Thanks
I think u should close the window first. Because the ball would maintain the speed of that instant when it was thrown up and u along with the car would achieve some higher speed in that small time interval due to the acceleration of the car, so the ball can hit on ur head and bounce off through that open window. I hope you don't wanna loose your ball.
Lets see what these old guys have to say about frames of reference. ruclips.net/video/bJMYoj4hHqU/видео.html
The inertial Frame based on the seated person on a moving planet. The frame of reference is related only to everything on earth because the reference frame is only to that environment? The frame relevant to the moon is different because the moon is not part of the frame under discussion. Is that right?
Would you be in an inertial frame of reference at the North or South Pole?
Earth is revolving, in a (almost) circular orbit, around the sun.
She really wanted to be in a non inertial frame
Non inertial frames are way more fun.
Cheers,
Dr. A
sound coming from writing on the board
Great explanation
Thanks Peyton.
Cheers,
Dr. A
The professor is wrong. The equivalence principle (made famous by Einstein) says that gravity and acceleration are indistinguishable. Thus, any time your scale reads non-zero you are in an accelerating frame. Only observers who are in free fall are in inertial frames.
When are the office hours 🤔
Really very helpful for me,
Love from Pakistan 🇵🇰
Thanks
Hamza younis,
Glad to hear it. Thanks for the comment, and keep up with the physics!
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A
Everybody says that the acceleration should be zero or the frame should be in constant velocity
I don't understand what is a frame
perspective
Superb
I am confused and no one will help me. (1) I am told there is only ONE type of inertial frame of reference. (2) meaning if i do a physics experiment in ANY inertial frame i will get the SAME RESULTS no matter what inertial frame i am in (3) Disregarding earth spinning and angular momentum (acceleration) I am told earth is an inertial frame. (4) I am told being in outer space at a constant velocity is an inertial frame. OK THESE STATEMENTS CONTRADICT ONE ANOTHER !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Because if that were ALL true then that would mean that i could do physics experiments in outer space (at a constant velocity) and then do the SAME PHYSICS EXPERIMENT on earth and get the SAME RESULTS. But that IS NOT TRUE. THAT IS A LIE. If i am in outer space(at constant velocity) and i hold a ball out and let go of the ball with out throwing it or pushing it in any direction the ball will just float there. But on earth if i do the SAME experiment the ball will fall to the ground. So there are (1) more than one TYPE of inertial frames of reference OR (2) earth is NOT an inertial frame of reference. SO WHICH IS IT !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Why wont any one answer me???????
Standing on earth means you are constatly accelrating at 1G upwards. Saying that it is inertial frame of reference is not correct. Its newtonian inertial but not relativistic. Maybe i am wrong...
QUESTION............When someone says a point in space.......meaning having no real volume. Does that really mean it has NO volume or does it mean the volume is smaller than a plank length(volume) and so it is there but it is an undefined volume of space ???????????????????
Wow, outstanding question. It's a very classical definition saying "a point in space" which means zero volume, but of course you're right, we should really be talking about a Planck volume. That is the smallest volume you could ever hope to measure. Which, of course, is pretty darn small. Wikipedia has a great entry on Planck Length. Check it out.
Cheers,
Dr. A
Your answer to the girl was not clear. I would have told her that she was not in an inertial frame of reference unless she was in a state of freefall. One way to test if you are in an inertial frame is to drop a ball, and if it stays where it is, you are in an inertial frame.
Excellent comment. Here's a very good explanation about this: www.physicsforums.com/threads/is-a-falling-elevator-a-valid-inertial-frame.331302/
Cheers,
Dr. A
The scale should read zero in an inertial frame.
Is he mirror writting everything?
Here's what i get "In what frames Newton's Laws Valid those are the Inertial frames of reference
''
But the earth spins at a constant velocity.
Doesn't that mean that we are in an inertial frame.
The earth rotational acceleration must be equal to 0 or extremely close to 0.
Because if it wasn't, would that make the days shorter as time passes?
+Manuel Rojas Velocity is a vector, not only a number. The magnitude of our velocity is constant, but the direction of our velocity is always changing, because we are moving in a circle. Thus, we have an acceleration toward the center of the Earth at all times.
+Alex Glisson
Alex is correct. The earth spinning means we have a constant "speed" (the magnitude of velocity) but the direction is always changing. Since acceleration is a change in velocity over time, and your velocity right now is changing (specifically, you are moving in a circle, thus the direction of your velocity is changing), you are accelerating. For circular motion, this is what we call centripetal acceleration.
Cheers, Dr. A
+Manuel Rojas nice question
+Alex Glisson thanks for the answer
+Matt Anderson thanks for the answer
Thanks
Gunna go ahead and hit that subscribe button. Thanks for the help!
During free fall is the normal force zero? If yes or no please explain why
Also why does a body in free fall experience no force even though it is accelerating
Yes, during free fall the normal force is zero. The scale does not push up on the person.
Cheers,
Dr. A
Left handed?
Awesomee
"Awesomee" - that's like a little extra Awesome.
Cheers,
Dr. A
Can inertial frames even exist? If we take a maximally macro view of the cosmos everything is accelerating away from each other at an increasing rate. Therefore a frame can only be inertial in the micro. Is a frame truly inertial if you ignore variables?
+Wes Hughes It depends.
Wes Hughes Nothing is inertial,we just consider.
Which I think constantly shifts? Just a doubt, acceleration of individual masses also causes the location of COM to accelerate right, as every mass unit has a different acceleration?
Wes Hughes theres no such thing as an inertial frame of reference in this universe !! Lol
Wes Hughes I agree theres no constant speed for anything in the universe.
Wait, what university does this professor teach in?
Obviously its australia. everything is backwards/upsidedown there
There is no one correct frame of reference, so to say the entire universe is expanding is irrelevant. On the other hand it could be argued that everything is motionless relative to itself , so EVERYTHING is a inertial frame of reference i would think
If Earth is accelerating then why there are always 365 days in a year?
Acceleration= change in velocity upon time taken.
since there is no change in speed the time required for revolution remains same. Hence same no. of days in a year 365.25 but we consider 365 days and add an extra day every leap year because 0.25 days ×4 = 1 day. But since direction of earth is changing continuously
so velocity changes continuously Hence earth is accelerating.(Velocity = Displacement/Time).
Hope this helps.
Rukul Singh you are telling that there is no change in the speed, that means it is in constant velocity, this means that earth should be an inertial frame is refrence, which means wrong!!
accleration is not only due to change in velocity!! but also due to change in direction of vector..
Technically, the spin of the earth is slowing down due to the gravitational force of the moon. A day used to be 16h a few million years ago. The mass of the sun is getting lower too, so the earth is getting further away as gravitation decreases. If earths tangential speed stays the same, a year will become longer, but days will become longer too so it will take "a while" before a year is more than 365 days. But both of the accelerations referred to in this video are radial. Since both the earth and a point on the surface of the earth are moving in a circular motion, they have radial acceleration towards their centers of rotation, the sun and the absolute center of earth's core respectively. And since a point on earth can be towards or opposite the sun with opposite velocities relative to earths orbit around the sun, the radial acceleration will fluctuate. But physics is about simplifying problems into practical models so we ignore these relatively insignificant accelerations. If this bothers you, you can always become a mathematician :)
QUESTION...…...If I am in a space ship in outer space with no planets or any mass near the ship and I am moving at a CONSTANT speed then I am in an inertial frame of reference. I can prove it cause when I put 100 N of mass on a scale it weighs ZERO. Also if I hold a ball in the air and drop it the ball does NOTHING. The ball floats and stays where it is relative to me and the ship. If I am in a space ship accelerating at 1g (9.8m/sec2) then I can prove I am in an accelerated frame of reference. Because if I use a scale and weigh something a 100 N it will weigh a 100 N due to the fictitious force produced by acceleration. Also if I drop a ball in the air, on the accelerating spaceship, then the ball will fall in the opposite direction of the acceleration due to a fictitious force. So why would I not say that earth is an accelerating frame of reference??????????????????? On earth a 100 N of mass weighs a 100 N due to a fictitious force created by warped spacetime. Sounds like an accelerated frame of reference to me. Fictitious forces are associated with accelerated frames of reference and gravity is a fictitious force. Also when I hold a ball out in the air the ball falls in the opposite direction of the acceleration. It does not float there and not move like in outer space at a constant velocity. SOUNDS TO ME LIKE EARTH IS A NON INERTIAL FRAME OF REFERENCE?????????????????????????????????????????? You know if you and your students and your classroom where on a spaceship accelerating at 1g (9.8m/sec2) and all the windows were blacked out. And a student said we are accelerating. Would you answer back and say sarcastically...……….."Do we look like we are accelerating?". Would you be the crazy one or the student in that scenario. Because the spaceship going 1g sounds just like earth to me. ALL THE PHYSICS LAWS seem to be the same weather you are on earth or in a spaceship going at 1g. My final question is...….If the 1g accelerating spaceship is definitely in an accelerated frame of reference then how can ALL the physics laws be the same with earth if earth is in an inertial frame of reference????????????????
JBSC,
Great comment, thanks. Very valuable insight here. It's true that technically gravity has been replaced by warped space-time in general relativity. With Newton's Laws we approximate inertial frames because they are VERY close to giving us the correct answers, thus is valuable for predictions here on Earth.
Nice work!
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A
👍👍
So is Benedict Cumberbatch behind a glass panel socially distancing from his students and he's writing backwards? LOL.
Michael Rayo,
Yep, safety first.
Not writing backwards (I'm not that talented). The board is called Learning Glass. You can check it out at www.learning.glass
Cheers,
Dr. Strange
are you right handed???
The Geostationary Satellites, are they in Inertial frame of reference with respect to Earth.
No. Since they are moving in a circle, they are accelerating. Thus not in an inertial frame.
Cheers,
Dr. A
Matt Anderson thanks
Drawing with a paint pen backwards to avoid blocking your students from reading your writing? Impressive. Plus the genius it takes to record your lectures these days? Your students aren't doing sentences in detention, that's for sure.
Thanks for the comment. I'm still having fun.
Cheers,
Dr. A
Is he writing in reverse?
thanks
You are very welcome. Glad to assist.
Cheers,
Dr. A
why did you subtract mg from normal force?
Anshuman Srivastava ...because the respective vectors of n and mg have opposite directions
Isnt there an additional force other than the m*g and the scale? The force of inertia opposing the g acceleration? When i accelerate my car , a force pushes me back ,opposing the acceleration. Doesnt this force have to be taken in consideration? Sorry, it was a long time ago when i went to school.
Time ic certainly independent of reference frame. A spinning cd disk
always take the same time for one rotation whether it is moving along
axis of rotation or not.
vixra.org/abs/1807.0027
Thanks for the comment, but I don't agree.
Time is relative, and as Einstein said, "moving clocks run slow." Which means that if you send a clock on a rocket at very high speed, it will run slow (as viewed from earth). This simple statement leads to some fascinating (and mind-bending) results, such as the twin paradox:
Most people have heard of this, and know that if you separate twin brother and sister at birth, and send the girl on a very fast space ship for a while, when she returns she will be younger than the boy. (Since "moving clocks run slow".)
So what's the paradox? The paradox is that if time is relative, then the girl on the spaceship looks back at earth and says that the boy's clock is running slow, therefore he must be younger when she returns.
Hmmm...chew on that for a bit.
Cheers,
Dr. A
Paradox is a result of inconsistency in theory. In this case, Special Relativity. This is why Einstein's theory never becomes a physics law. It remains as a theory because it can not be verify. Apparently you have not read this paper yet.
vixra.org/abs/1807.0027
MR ANDERSON ANDERSON..................
Matrix style.
Cheers,
Dr. A
Is this guy writing everything backwards just to flex?
is he writting backwards??
+Kent Camz No, it's explained here: ruclips.net/video/CWHMtSNKxYA/видео.html
Cheers, Dr. A
+Kent Camz
actually, he's talking backwards but the video is played in reverse
Now that's ynnuf.
Matt Anderson This comment is too smart to get the credit it deserves. "Now that's enough"/"Now that's funny" :D
As earth is a non inertial frame then why laws of physics are applied to it..
As laws of physics are only valid for inertial frames
@@muhammadosama3295 technically speaking Earth is not a inertial reference frame. But it's approximately inertial because centripetal acceleration is so small.
And you can formulate Newton laws for non inertial reference frame by adding so called fictitious forces. So physical laws can be apply to non inertial reference frame
I say your wrong. I say the scale in an elevator has to read ZERO newtons for the person to be in an inertial frame of reference. If you disagree then EXPLAIN why when i am in outer space moving at a constant velocity and am in an inertial frame of reference and i weigh myself i weigh ZERO newtons????? If the scale reads 100N then i am in the same frame of reference as the earth. AND I SAY THE EARTH IS IN AN ACCELERATED FRAME OF REFERENCE. Why am i wrong???????????????????
Check my other reply.
Thanks for chiming in!
Cheers,
Dr. A
I like your board
+NinoDroid Thanks! You can check it out in more detail here: www.learningglasssolutions.com
Cheers, Dr. A
Very nice sir hi ji good morning ji
👍nice explanation!
CHALLANGE TO ANYONE WHO thinks earth is an inertial frame and "free falling" is an accelerated frame of reference. THEN PROVE IT BY ANSWERING MY QUESTION !!!!!!!!!!
Let us say you are in an elevator WITH NO WINDOWS on the moon so there is no air. And the rope holding the elevator breaks on the 500th floor and you and the elevator starts "free falling". And lets say i am in a space ship in outer space moving at constant velocity. WE BOTH WOULD SAY I AM IN AN INERTIAL FRAME. Now you say "free falling" is an accelerated frame of reference. So YOU ARE SAYING we would be in DIFFERENT frames of reference......you in an accelerated frame and me in an inertial frame. SO YOU SHOULD BE ABLE TO PROVE IT EXPERIMENTALLY...RIGHT??????????????????????? Cause if we do identical physics experiments there should be at least ONE experiment where we get different results.....right. WE BOTH AGREE WITH THAT RIGHT?????????????? So tell me what experiment would you do to PROVE you were in an accelerated frame of reference while you are "free falling" inside your elevator???????????? If you can NOT think of an experiment that would give us different results then you must admit that "free fall" is an inertial frame because WE BOTH AGREE THAT me in a space ship in outer space moving at constant velocity is AN INTERTIAL FRAME.
And guess what. If you .......while in your "free falling" elevator would hold a ball out and let go of the ball with out applying any force to the ball. Guess what the ball will just float and not move relative to you. Just like it would for me in my space ship. So that would be the same result. What experiment will you tell me about that gives different results???????????
John,
Excellent, excellent comment. I especially love the caps.
What you are describing, of course, is exactly the thought process that Einstein went through when he developed his general theory of relativity. Which is, of course, a much more exact theory of gravitation, but is a bit beyond the class that I'm teaching here.
I'll try to add it in a future series.
Cheers,
Dr. A
@@yoprofmatt ....OK so i am right. I mean you agree...right. I thought i was going crazy. I was just watching an "entertainment" type physics video about frames of reference and said earth was an accelerated frame. So everyone said i was crazy. So i said don't all inertial frames have the same physics and they said yeah. So i said to them why on earth does a ball not float when i let go of it like in an inertial frame. They said when you let go of the ball it falls cause then it is in an accelerated frame. So i cut and pasted what Einstein said about "free failing" being inertial and earth being equivalence to an accelerated frame. They said Einstein was wrong. So that is when i went crazy and posted my challenge on a bunch of physics videos labeled frames of reference. Anyways thanks for your time i will have to check out some of your videos
@@johnblacksuperchemist2556 did you get which video he talks about this? Or any other videos?
My book confuses me because on the elevator problem it says "if the elevator accelerates then it is NOT an inertial frame"...then later a problem asks "what does the scale say if the elevator accelerates upward..." Yeah that's confusing.
Q1: Inertial frame moves at constant velocity... But with respect to what? Another inertial frame?
Q2: Inertial frame does not have acceleration with respect to what? Another inertial frame?
Q3: You are saying that the elevator is not a inertial frame because your weight is more than 100N. Where did you measure your weight at the first time? On earth? Are you not already considering earth to be an inertial frame then?
It seems that your logic has a circular fallacy.
Excellent questions:
Q1: Yes
Q2: Yes
Q3: Yes we are considering Earth to be an inertial frame (it's not strictly true, but close).
Cheers,
Dr. A
@@yoprofmatt WIth due respect Sir, I have made this video on the frame of reference... You may watch it... ruclips.net/video/_pGJ2IhL25M/видео.html
Some years ago, the physics prof. in the physics classical mechanics course I was enrolled in asked the class: What is an inertial reference frame?
The class was comprised of about 100 or so physics and engineering majors. But nobody had an answer. The prof. waited... crickets. (This was before the advent of laptops in the classroom, but even so, I am not sure that would have helped, since, for example, the current Wikipedia definition is wrong.) Still, none of the physics and engineering students had an answer, presumably, because they understood that stating that it is a reference frame with constant velocity begs the question constant with respect to what? Finally, the prof. gave his answer. An inertial reference frame, according to the prof., is a reference frame in which Newton's Laws are valid.
@@larrymusa6717My humble request to you... You can watch my video that is given in the link above and see if you get a satisfactory answer to your question or not...
Edventure - Unfortunately, your definition is garbage, but you get partial credit for understanding that defining an inertial frame as a frame that is not accelerating is also garbage.
I gave you the definition: An inertial frame is one in which Newton's Laws are valid.
Could you pick a more squeaky pen holy shit man!
Plain wrong. Velocity relative to WHAT? Acceleration relative to WHAT? Its not the rotation, which makes the lab-frame "non-inertial". Its gravity. Your explanation of "inertiality" with the help of "scale" and "weight" is completely misleading/wrong. If at all, "inertiality" could be substituted by "weightlesness". Like on the ISS ...
lmao..This guy speaks like Donald Trump..
Raphael Johnson,
Tremendous! That's yuge.
Thanks for the comment, and keep up with the physics!
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A