More on Newton's first law of motion | Physics | Khan Academy
HTML-код
- Опубликовано: 17 сен 2024
- Courses on Khan Academy are always 100% free. Start practicing-and saving your progress-now: www.khanacadem...
Newton's First Law (Galileo's Law of Inertia). Created by Sal Khan.
Watch the next lesson: www.khanacadem...
Missed the previous lesson? www.khanacadem...
Physics on Khan Academy: Physics is the study of the basic principles that govern the physical world around us. We'll start by looking at motion itself. Then, we'll learn about forces, momentum, energy, and other concepts in lots of different physical situations. To get the most out of physics, you'll need a solid understanding of algebra and a basic understanding of trigonometry.
About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.
For free. For everyone. Forever. #YouCanLearnAnything
Subscribe to Khan Academy’s Physics channel: / channel
Subscribe to Khan Academy: www.youtube.co...
As a high school dropout I was not confident about going to college, but went anyway in my forties, graduating with a BS biology at age 46 thanks to you. I certainly would have dropped out a million times if not for your help.
I now know for a fact that I can learn absolutely anything.
I am starting my first teaching position as a high school science teacher (yay!!!) and am revisiting your content.
I know the value of your work and I thank you from the bottom of my heart.
When I am wealthy I will make sure all of your operating costs are met.
The whole wide world needs this.
I applaud you thats so great!
When you realized Khan Academy taught you everything about Newton's first law of motion in just 10 mins while the school spent almost 2 to 3 weeks trying to explain. Plus, the students won't even understand what the physics teachers are saying. So you will save a lot of time. Please considered donating if you really wanted to learn more things from Sal, the students hero and the teachers best bud.
Human will learn and try to understand thing when they actually want it hence curiosity is primal.
You came to this video because you want to learn, you want to know. Schools is the opposite, only small amount of people actually sit there with curiosity.
Lack of spirit in class would actually affect the teacher, hence most of the teacher probably think: "They don't listen anyway, I should just phrase the book and let the student study by themselves before exam."
Khan Academy can't see the audience that's why these people can keep on teaching with spirit.
Immense truth
@@reginaldrasyid2456 FAX
I like how Sal gave credit to Galileo for his work instead of everywhere else where he isn't even mentioned much. This guy did soo much more than just figuring out the law of forces.
People that dislike this kind of videos are MORE LIKELY have no interest in knowledge, there's nothing to lose when u learn. I cant even---
I cant even (what)me:yeah
Hi Sal, this is comment 4 on this video:
So, to know the actual velocity of any object in space we take the reference object with 1 unit mass which is given 1 unit force to accelerate it 1 unit velocity and call its initial velocity (before we gave it 1 unit force to accelerate it 1 unit velocity) the reference actual velocity in space. If this reference object have a faster initial velocity, it will require less force to accelerate it 1 unit velocity. Hope to hear from you Teacher Sal.
I'm not even in school and I'm watching all his videos lol
😊
You have no life
Riddle me this: If two cars are on the road, one goes 40 miles per hour, and one goes 60 miles per hour, yet, they cross. How is this possible?
Because they go on different direction? @@lennonsliger3632
Correct.
Sir Isaac Newton is hot.
Vish true
Vish I love him because if it wasn't for him we wouldn't have some of the brilliant technology and inventions today :)
Peliyx OR I still hate him for the unending torture given to students for years and years....imagine students going into a bottomless pit year after year....
XD what?
i thought i was the only one observing that. LOL
wow that's a very well drawn airplane
thanks Khan academy you just helped me with my homework
How could someone possibly dislike any one of this gods videos
Easy, they (we) clicked the dislike button.
good*
+KapplePlays I'm pretty sure he meant god's. Which is quite pathetic if his god is a simple human. Apparently his standard for godhood is quite low.
Lance Roark A peice of dirt could be a god.
Iron Sunnyvale ata god na hobe good
I have a test tomorrow on Newtons Law in science and we have learned it for four days now.We barely spent time on Yhe third law of motion.I am good with the first law,but not the other 3.
There are three, not 4
why would anyone dislike this video
ikr
Infinity Games gotta have haters
I have no fcking idea
Sal your 1 of the best teacher i know...i love watching your video every day! Its my hobby! ;-)
You saved lot's of people, man 😊 I have a test tomorrow and I watched the few videos of yours, and I think I understand everything, I'm super happy, thank you 😃
I think another good way to think about the second part is that objects on Earth that are in a state of rest are also moving uniformly forward due to the Earth's constant rotation. Amazing videos man!
Hi Sal, this is comment 3 on this video:
I suggest the following experiment to determine the actual velocity of any object in space:
If we take (for example) a 1 unit mass object and give it 1 unit force it will be accelerated 1 unit velocity. So, an object with 2 units mass will need 2 units force to accelerate 1 unit velocity. If two objects require the same amount of force to accelerate 1 unit velocity they have the same mass. So, to know the actual velocity of any object in space ... comnt4
@aviator1341 The example you give presupposes:
1) that heliocentrism is true,
2) that the two forces of gravitational attraction and momentum previously acquired can go on giving a non-equilibrium equilibrating around a circle or ellipse,
3) that - which is not the case - "uniform" CIRCULAR movement is uniform in the sense required by this law.
Show how one of the three is not presupposed by your answer, or admit to two unprovens and one clear untrue in ur arguments or explanations.
And of course gravity is acting on the ice cube pulling it down creating even more friction.
Delta Side yes, on a straight line the gravity act to stop the ice and in a slope the gravity will accelerate the ice
Hi Sal, can you confirm the following:
an object alone in space can't tell if it is not moving or moving at a constant velocity.
But if we take a moving object we will need some force to accelerate it or decelerate it or change its direction and we will need more force to accelerate it more or decelerate it more or change its direction more and so on. So, doesn't this need for force to accelerate or decelerate or change the direction of any object in space means that this object is only moving.
1. Stationary objects with more inertia are more difficult to move.
Stationary objects with more inertia have more mass.
2. Moving objects with more inertia are more difficult to stop.
Moving objects with more inertia have more mass.
The airplane example also illustrates that all movement is relative. Perhaps that would be good to bring up again if you eventually move on to the Special Theory of Relativity.
I love his videos. They help me soo much. Love the website as well! BTW, how can I guy be so good at writing with a mouse. My letters turn out like spaghetti. He is so smart and talented with the mouse. XD
its not mouse. Its a wacom tablet. Hardware for computers to replace ur mouse. It is actually used for drawing but he used it to teach so yeah. I have one too but im using it to draw
HAHA.But even with that tablet thing I couldn't write that well. HAHA
Nice video
This basicly means kinetic energy can be turned into potential energy with an outside disturbance, as well as an object formulated in potential energy can be renewed as kinetic energy with an outside disturbance.
I love khan academy keep up the awesome work guys
Sal is a genius teacher. I wish all teachers were this good, this dedicated. On the subject of cats. Dubstep Cat - somethings cannot be unseen.
A question about the necessity of unbalanced force.
Suppose I throw a ball with 5N force and there is no gravitational force. The air resistance is also 5N. Then won't the ball stop? But here the force applied to both sides is the same and balanced then why did the ball stop considering that it should only be stopped when it meets an unbalanced force?
Definitely better quality than the one he made years ago.
Sir What force keeps the planet rotating and why it does not collide with sun due to force of gravity that pulls the earth?
Thank you for those beautiful explanation!
"pasted" at the back of yo seat... lmfao epic video ty
When an object is pushed in space, say a ball is thrown, it will never stop moving. Unless acted upon by and unbalanced force such as gravity, an asteroid, or anything else. If it even hits in to any of those things knowing how big space is. Point being, yes on Earth we intuitively know that you must keep adding force to make an object go. But because I knew about how some physics in space works, it was intuitive. So for me, that is the best example for law 1.
instead of starting these videos thinking about trying to get it done, or trying to make it easy, ask yourself about the deeper meaning about what you are trying to learn. You take that approach to these videos, and Sal will blow your mind. You are trying to learn after all.. right?
Well actually, the rock is "at rest" because its velocity, relative to the ground at least, is zero. Whether or not an object is at rest is determined by the NET Force or "resultant" force, not whether or not there is even a single Force present.
Although, you've probably watched the other videos and corrected this misunderstanding by now.
In only 9:31 I went from hating physics to being amazed by physics. Thank you.
@Masterlink981 I said "... with iceblock and magnet circling another fixed magnet on ice?" - Not "... with iceblock functioning as magnet circling another fixed magnet on ice?" Instead of "... with iceblock and magnet circling another fixed magnet on ice?" i could have said "... with magnet on skates circling another fixed magnet on ice?"
I never stated the iceblockitself should be magnetic. Now, do and film the experiment if you want to. One magnet fixed, one with friction very reduced.
I can't imagine that anyone can explain the laws of motion just in 10 minutes it is very fascinating 😢😢
great stuff :) it really help me with my grades. thankyou for producing useful contents
@aviator1341 - AND itself circling the sun - not proven. Same speed - when it is circling, it is not same speed same direction. Uniform movement applies to movement in a straight line forward, not to circles.
KHAAAAAAAAAAAAN!!!!
(Movie Reference)
I do find that as fascinating as you do! Awesome :)
+Courtney Tanguay yes it was really spectacular video
Ok minus the gravity force, an object would continue to move continuously ... and since an object will almost always experience a force of gravity (friction) - aside from floating in an empty vacuum of space with no nearby objects that could produce gravity ... then the objects will almost never exhibit continuous motion, but in an empty vacuum it would behave this way.
So for example, if me and you were in an empty vacuum and you pushed me and I started to float away, my velocity would always remain the same, unless the force of gravity acted upon me.
If I have a rope and apply equal force to each side. There will be no net force. But if I increase the force on each side eventually the rope will break. Does that mean our human bodies are constantly battling out the pull our earth is making to the left and to the right of us??
Hi Sal again,
Since we need more and more force to accelerate or decelerate or change the direction of any object in space more and more, this means we will need an infinite amount of force to accelerate any object to an infinite velocity or to decelerate it to a zero velocity. Can you confirm it.
The last example was great
" You cannot tell whether you are moving at a constant velocity or at rest. " Why don't they say stuff like this in textbooks? It's fascinating too stop and think about the implications of this law, and this statement. Our world, in fact our galaxy, could be moving at "warp speed", be it constant warp speed, and we would have no idea.
I'm sure what he's trying to say is exactly what he said. Any moving body will keep moving in the same direction with the same speed indefinitely, unless it is compelled to change it's state by an outside force. Yes your car wouldn't keep moving (on earth) because of the many outside forces on earth, other bodies such as Nitrogen and CO2 in the air and also gravity. But if you were to push your car in a vacuum and out of the influence of any gravitational force then it's state will never change.
Now I don't claim to be right but this is just my intuition of the subject. I am open to any and welcome any proof that I'm wrong. Also I love the videos! They have helped me a lot.
One question, does anyone else only watch the video if Sal is teaching? I find myself avoiding all others.
Yeah, they can also delete all of their videos, but that wouldn't make much sense would it?
Did you think I was implying they can't do whatever they want on their channel? I was asking for a reason. @lagozit gave a good one. You should think before you comment.
What program is used to draw/write everything?
If a ball is thrown into vacuum (space), it might have no friction , so could it move indefinitely if we ignore it’s possibilities of colliding with something
The law States that an object at rest or uniform motion in a straight line unless compelled to change by an applied force .
Galileo told that this law will only obey when the object is in vacuum or friction free environments
Are you saying that it doesn't, or does work in space?
+Cameron Petet He is saying that it does work in space, being that space is a vacuum. Any lump of matter in space, if already moving, will only travel in a straight trajectory, unless influenced by the gravity of a planet or star for instance, or, if e.g; hit by a meteor or other body.
@itked3 He's making HD versions, my guess. He's also expanding on the subject.
The probe fired from the ISS would be constant travelling 'uphill' against the Sun's gravity. Without using its thrusters or using other planets' gravity to accelerate, the probe would eventually slow down and fall back towards the Sun.
My physics teacher doesnt give us textbooks. He gave us a piece of paper with your website on it XD He knows we aint gonna read. Unfortunately no one in my class except me watches ur vids. Poor poor FOOLS XD
dat last example doe!!!!!
Very interesting and nicely explained but i have a question that in space gravity is there of planets and other bodies?then the ball will stop?right?
@Masterlink981 I said video games did not need to get them right in what they are telling. Not that they could not. Of course they can as well as they can the opposite. But I said they are electronic things, and their electronics seems to follow natural laws - like those of Newton.
The second part ... or in uniform movement straight forward ... is it anywhere examplified in all the universe? Is it even proven except by Newtonian Heliocentrism which it explains?
A stone on a string does exhibit other features, pretty salient and relevant, than two forces acting on stone, inertia from previous moves and centropetal pull of string, namely superior solidity of string.
Could that be repeated with iceblock and magnet circling another fixed magnet on ice?
this probably a stupid question....but I'm curious...if newton first law states that it will continue to move straight-forward..if air is not present....why does the earth orbit around the sun....why does it not continue to go straight instead of orbiting ???
ive taking my first physics course next year...can you suggest any beginner physics book?
So when you push something over a carpet, and want it going at constant velocity while overcoming resistant forces, do you apply the same force continuously? I thought this would give an acceleration.
I keep getting mixed up with applying the same force constantly (once overcome friction), whether it will always accelerate or if there's a time when it travels at constant velocity. Thanks, hope it's a clear question. It's weird how something so obvious we experience all the time is confusing me aha
These videos help with a lot, thanks.
You can apply different amount of force. The air resistance and the friction will apply a particular force on the object. If you can apply that same amount of force in the other direction, then the object will move at a constant velocity. If you put more force, then the object will accelerate to a higher velocity.
@nat1XP It is called force
your drawing skill is excellent
Great explanation from an historical perspective!
at around 5:00 you said that things will not go forever actually they will but the out side force is gravity and friction
i want formulas! equations! :(
So, if you were to have ice in space with constant velocity, no forces like gravity could act on it. So would it go on forever?
what about even in space there are particles everywhere wouldnt those few particles eventually act upon any object or are they too small to have any reasonable affect
What is a force? Uh, an "influence" that causes...". What then causes this influence? The answer obviously must be applied energy. How can energy be applied, but by a force only? No, all we have to do is to release energy and then it "applies" itself. See it explained here: watch?v=oee0-S7ipfo
If we slow down the velocity of any object in space to zero, then the rest of the objects in space will go past the slowed object extremely fast. Because all the objects in space are going round the gravitational center of the universe. So, can we be even theoretically sure we can slow any object to zero.
No. For one thing, with respect to WHAT would you make the velocity zero? You cannot establish a velocity unless you can give that velocity in terms of some reference frame. And unfortunately, there is no such thing as an absolute reference frame, so there exists nothing from which to establish an absolute velocity of zero. There is no reason to. If the velocity is constant with respect to any inertial reference frame, the laws of physics are identical to any other.
You stated the first law of motion beautifully. Bravo good sir, keep up the good work.
With the plan analogy would you not feel the plan decelerate?
newgamer85 You would because once it decelerates it is no longer going at a constant velocity
@someonetoogoodforyou In a way yes, you see on earth we are interacting with more gravity at our feet and less at our legs. This makes very little difference in anything on earth, but in a black whole the gravity at your feet is so great that you begin to stretch out until you snap into 2 then 4 8 16 and so on until you separated into your different atoms. This process is expressed into the super technical term spagetification.
@khanacademy can you make a lesson on how you make your lessons?
you have been amazing for me
Rock is not at rest since it's attached to the earth which is moving round and travelling through space. Is that facetious or what? Nice presentation though, like the drawing gizmo, will have to try it out.
It's not moving because there is no force acting on it. Your statement is having the sun as a reference point...
+Harvey Bosire Hi Harvey, appreciate the reply. With reference to sun etc. are we not all travelling through space? Also, been watching a certain Mr Feynman who talked about the atoms "jiggling" even in a solid so even the rock will not quite be at rest. Hmmm...
he taught very well,eth will stay on the normal when there is no unbalanced force
Your drawing skills are sick what program is this
These five dislikes are probably my class mates, lol
guys do some research about PHYSX!
A body at rest will remain at rest and body in motion will remain in motion until roundhouse kicked by Chuck Norris.
this video was amazing, just amazing
I just wanted to say Thanks to Sal Khan!
Math and physics have a rather bad reputation because it's commonly regarded as something "strange" and "alien".
But in fact these subjects are never more confusing than they have to be; everything is always presented in as clear and compact ways as possible (like formulas, for example), and some things may seem complicated because of an unfamiliar notation (like the vector notation for example, which can look really complex until you realize that it's a fairly simple kind of notation).
@itked3
These videos seem more conceptual, while the older ones are more math-based descriptions of Newton's Law. Just a hunch.
Granted, in space, there's no gravity, no air, therefore no friction. But what about extraterrestrial (space) dust? Doesn't that create friction, however minute? The little physics I had in college was a long time ago. So forgive my ignorance.
Well, you said that an object changes its state of rest or motion when an unbalanced force acts on it. What is the force that makes the earth or any other planet for that matter, revolve around sun?
OMG NO NO noOOOOOO !!!! M IN THE BLISS OF HOLIDAYSSSS SO NOOOOO
bliss of holidays where in you can think of many things to do and can accomplish none of them :P :)
lol yea xD
Earth own Inertial force makes it to revolve around SUN as there is no external force to deviate its path.
Jahnavi kolengode Just google it
It’s crazy to know that we feel like we’re still and not in motion inside a plane. It’s the same experience as me standing on ground level.
Sir Isaac Newton you are amazing person
well actually, the rock isn't "at rest" there is force being applied to it, gravity.
build a school here in philippines, i would love to enroll and in the future i would made my sons and daughters enroll as well.
Esse vídeo é ótimo... Obrigada...Me ajudou bastante.
Andressa Teodoro pois é, esse cara é bom
doesn't khan already have a physics course? why are you making videos of the same subject twice? :O
What I don't understand is that if you were in a car and moving at a constant speed, that would mean the net force is zero. But how could the car be moving if the net force is zero?
Net force doesn't apply to an object's speed or velocity.
on the whole system of car and you , there is no net force . however there is internal force which is capable of changing momentum.
@Masterlink981 As for video games, it is generally assumed they apply to the electronics involved. With interatomic attractions duly replacing gravitation. Not, however, to each scenario presented by the video game, since there could be scientifically impossible ones. As for cooking and singing, it is generally assumed they apply to atomic movements making up heat and sound. Words in a song may also portray sth against the laws, just as in a video game.
what program you use for do this video that black board
There's a chance the rock and ice could break apart if the forces are too great.
Yeah, and I guess that's where the modulus of elasticity kicks in.
if the car is moving in the vacuum, will it stop eventually? or keep moving?
That doodling looks FUN! :)
@thekraken1000 But cats help the learning process! There's so many analogies in physics and math that for some reason people choose to explain in terms of cats.
i prefer the textbook version
@YoungPimpChimps You're a badass dude.
@itked3 because most people dont know where it comes from...