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Kinematics Demo: Cart and Ball
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- čas přidán 19. 08. 2016
- This is a demonstration that gravity alters only the vertical component of velocity of a projectile. A ball is projected vertically from a cart that is moving with constant horizontal velocity along a track. The ball returns directly back to the cart. From the cart's point of view, the ball goes straight up and comes straight back down, but from our point of view, the ball follows a parabolic trajectory, with its horizontal component of velocity matching that of the cart at each instant of time.
This demonstration was created at Utah State University by Professor Boyd F. Edwards, assisted by James Coburn (demonstration specialist), David Evans (videography), and Rebecca Whitney (closed captions), with support from Jan Sojka, Physics Department Head, and Robert Wagner, Executive Vice Provost and Dean of Academic and Instructional Services.
![One Dimension - Constant Velocity and Constant acceleration [Physics demonstration]](http://i.ytimg.com/vi/PCLjIjAUBnw/mqdefault.jpg)
Literally helped me so much in such a short clip. Thank you
Is this what Einstein said about relative motion. That it depends on frame of reference and there is no absolute frame of reference for motion in universe as newton envisioned it?
what happens if the track is curved (in circular) instead of straight?
ball will go in a tangential direction to the circle at the point of projection
but if the ball was forced by the plunger to reach a greater height the ball wouldn't fall into the carriage! So the demo helps to contrive the idea that frames of reference are important when trying to sell certain ideas and the earth doesn't move!
Well, you two Flat Earthers also assert that mercury is just silver water, and helium is lighter than vacuum. By the way, how many people have you blocked to date from your "free thinking" channel?
I see that you blocked *craigmont924* from your "free-thinking" channel. No surpise, there. He got you to admit that the evidence shows that the Earth is a globe.
Nice
Nice. Now reapeat the test with a slight slope for the rail :)
Lets talk about the gravity of the situation
Sir can you tell the materials used for this demo
What if Vi of the ball is increased
Would i get the same result if i did it inside a empty chamber? i mean, with no air involved.
Of course, if you apply external force only in y direction
Where can someone buy this type of plunger/launcher? Vernier? Pasco? Thanks in advance
I think we got it at Pasco.
I'm not sure where we got ours. I would try Pasco.
Whats the right view then ?
From my view or the cart ???
Either view is completely acceptable. Both observers see the correct motion from their reference frames, neither is preferred. There is no preferred inertial reference frame (Einstein).
Neither is right. They're both equally acceptable points of view.
Its upto the frame of reference. And tbh either of them is true. And this is the situation where pseudo force come into action. Sorry if im late.
TAKE MY BABIES
Trial and error. Increase the track speed and try again. Then slow the track speed and increase the height of the projectile.
Are we supposed to believe that no matter the force the ball comes straight back into the bucket? Pseudoscience. GTFO.
There are only two things that will make the ball "miss" the bucket, if you will. First would be acceleration, not velocity. That is, the cart might increase or decrease its velocity due to force applied or friction from the track - since the ball would "snapshot" the velocity at which the cart was moving past the sensor, if the cart then accelerated or decelerated, that change in velocity would not apply to the ball, and hence the ball could "miss" the bucket when coming back down.
The second thing would be air resistance. As the ball shoots up into the air, it starts being affected by air resistance, and that slows its horizontal velocity. Since the mass and volume of the ball differs from the cart, they would be differently affected, and so that may result in the ball losing its velocity dramatically while the cart "plows on" if you will (depending on its aerodynamics, of course). To picture this, think of the difference between a pingpong ball and a golf ball. The first would be greatly affected by air resistance, whilst the second not as much. The first would require less force to be punted as high as the second by the spring.
If this test were to be done in a vacuum with a frictionless track, you'd be able to send that cart by at supersonic velocity, and the ball could be shot as high as your vacuum chamber would allow (granted, the higher you shoot it the longer the track would have to be as well), and it would still inherit the horizontal velocity of the cart and land straight back into it at the end of its arc.
If you find this hard to believe, I suggest you brush up on your high school physics classes. Study Newton's first law of motion to be exact.
@@truthless4720 no.
Double the height of the projectile and keep the same speed (velocity) of the cart.
Same exact experiment, double the height/force of the projectile. Wouldn't work.
You can't argue that. Using word salad like acceleration vs velocity explains nothing. Wouldn't work in a vacuum either.
@@7shocker You should study Newton's first law of motion. Also, nothing I said was word salad for anyone who has passed a basic physics course in school. Sorry.
@@truthless4720 You can't argue my point. Why bother?
No amount of reading or studying physics disproves my claim. Double the speed of the cart and maintain the same force for the projectile or double the force of the projectile and maintain the same speed for the cart and repeat the experiment. What happens?
@@7shocker I've already argued your point before you even questioned me. I gave you the only two reasons why the ball would lose horizontal velociity at a different rate than the cart once it leaves the confines of the cart. It's simple physics dude. But sure, I can tell you again.
A body in motion stays in motion, assuming no external forces act upon it. Can we agree on this? If you had a perfectly frictionless, flat surface and you slid something along it, that object would just keep going until it either hit something or fell off the edge of the surface in question. It wouldn't slow down over time.
What causes an object, like the cart in the experiment, to slow down is mostly friction. So if you slide the cart down the track, how slick the track is and how much friction it "pulls" on the cart with determines how much it slows down over time.
Secondly, whenever something passes through matter, it experiences friction with that matter. An example of this is when you move your arm under water. How much friction the object experiences is determined not only by the shape of the object, but also by the mass and the velocity. A faster-moving object will experience more friction (as it's running through more matter in the same amount of time), than a slower moving object. Likewise, a bigger and lighter object will experience more friction than a smaller and heavier object. This is basically how flippers work. The same thing happens in air. That's basically how parachutes and kites work (heavily oversimplified, but whatever, that's not what we're arguing here).
In the experiment, the cart experiences a small amount of friction from the track, and both the ball and the cart experience a small amount of friction from the air as it travels through it. Outside of gravity, and the initial push, these are the only forces acting upon the objects in question. Since the push only sets the cart (and the ball) in motion, and then doesn't interact with them further, that leaves gravity. Since gravity is a force that's purely vertical, it only acts upon the cart by holding it down on the track, the ball by holding it in the cart, and finally again on the ball by pulling it back down into the cart once it gets punted out.
There is no horizontal force acting upon the ball or the cart other than friction. Remove the friction, and there is no horizontal force acting upon them. Hence, there would be nothing to change the velocity of the ball or the cart in a vacuum with a frictionless track.
Since we don't have that in this case, we have to conduct the experiment within the confines where friction has a minimal impact upon our experiment. As previously explained, the faster you go, the bigger impact the friction has. The higher you punt the ball, the more time air resistance (friction) has to act upon the ball.
Doubling the height the ball pops up would severely extend the time it stays in the air, and thus the time it is exposed to air resistance. That might well make it miss the cart on the way down. But that's the only reason it would do so.
If you claim there is another reason, I would like to know what force acts upon the ball (or the cart) in the horizontal direction that changes its velocity.