So an inelastic question is one where the energy is changing from one form into a hidden form to be gleaned. So you might have a ball of putty that falls on a surface and goes splat. And take some energy to deform the ball of putty and so the kinetic energy is not going to be conserved. A rubber ball, however, is going to deform and then under form again. And so it's back in the state it was before, which means there's no sort of hidden form energy there. And therefore it's going to have all its kinetic energy back again after it bounces. And another thing that's very good at bouncing is not just rubber balls, but actually steel balls. This is a mutants cradle. If you have a steel ball and a couple of these hit each other, then what you find is that they don't change shape afterwards. They don't change shape, they don't store energy anyway. And so therefore the energy that goes into the collision comes back out of the collision. Now if the momentum were conserved, there are many ways this could happen. If I've got one ball coming in, it could come to a stop and then four of them could go at quarter of the speed. That would conserve momentum. Or if I had one ball coming in, I could have two going off at half the speed. So there's all sorts of different ways I could conserve momentum in that collision. However, if I'm going to try and conserve kinetic energy, then this mass times V squared has got to be equal to the mass times the speed. So if I have four things going at a quarter of the velocity, that's going to have a much lower NV squared. Because the V has to be squared. And so I've got a quarter that will turn into a 16th. And so when you have just one, it turns out the only way you can conserve kinetic energy and momentum at the same time is if you have one bouncing up, exactly one. And similarly, if you have two bounce up all the way through to if you have four hitting ones, it's going to fly off a lot. No, in order to conserve momentum and kinetic energy, we're going to have four going on. Right, so there's a little bit of jiggle there. These have a little bit of stick. And so the collisions are not perfectly elastic, but they're very elastic. And so that's why you get the kinetic energy being mostly conserved.