4.Two carts, A and B, sit in front of you. They look identical, and you are told that they are made of the same material. Cart A is at rest on an air track and cart B is given a constant velocity directed to the right toward Cart A on the air track. Cart B collides with cart A elastically. After the elastic collision, both carts move to the right, the velocity of cart B being smaller than what it was before the collision. What can you conclude based on only what you have observed

Cart B loses some of its initial kinetic energy and cart A gains kinetic energy.

Explanation:

Since both cart A and cart B have identical masses, and cart B moves with a smaller velocity after the collision than it was moving with before the collision, and also, the collision is elastic. It implies that the initial kinetic energy of cart B equals the final kinetic energy of cart A and cart B after the collision.

Since the initial kinetic energy of cart B is shared between cart A and cart B and cart B moves with lesser velocity after the collision, it implies that cart B has a smaller kinetic energy than its initial kinetic energy before the collision.

And also, since cart A is initially at rest and moves to the right after the collision, it gains kinetic energy.

Thus, cart A has a higher final kinetic energy after the collision. Also, cart A has a smaller kinetic energy after the collision than the initial kinetic energy of cart B, since it is the difference between cart B's initial and final kinetic energies.

So, from our observation, we conclude that cart B loses some of its kinetic energy and cart A gains kinetic energy.

the answer is c. the lower legs are levers, and the knees are fulcrums. the ankles hold the loads.