Conservation of Momentum Question

K^2

Huh. I can't find any videos of separation of two air track gliders either. I'll give it another look, but maybe that's something that needs to be set up.

Might be easier without an actual air track. We have some carts on rails for similar kind of demos over in the department. There is a pair of blue tooth accelerometers I can mount on them. And these carts have a spring release built into them with a very sensitive trigger. These things go off all the time when students do experiments with them. I can weigh one of the carts down, trigger the release and record accelerations and integrated velocity readings.

Collisions are related to recoil, of course. You can look at recoil as time-reversal of the inelastic collision. But for it to be a perfect analogy, the inelastic collision needs to be set up so that the combined motion after collision is zero. Or look at it from center of mass frame where that's guaranteed to be the case.

None of it is quite as impressive as firing a bow, though. I don't think anybody is surprised that when one cart pushes the other with a spring, it pushes itself in the opposite direction. With bow, more things are going on. There is reaction of string against the arrow, pull of the string on the limbs, acceleration of the limbs... And all of it adds up to exactly the same thing. That would be impressive to show.

By the way, if there are any other common physics experiments that people are talking about, but there doesn't seem to be footage of on YouTube, let me know. I can probably set it up at the department. They have a room full of equipment just for showing demos to students.