You are given two carts a and b. they look identical and you are told they are made of the same material. you place a at rest at an air track and give b a constant velocity directed to the right so that it collides elastically with a. after the collision cart b moves to the left. what do you conclude? a. cart a is hollow. b. the two carts are identical. c. cart b is hollow. prove your answer carefully!

2. two cylinders of the same size and mass roll down an incline. cylinder a is hollow, while cylinder b is solid. both cylinder are released from rest at the same time. which cylinder reaches the bottom of the incline first? a. cylinder a. b. both at the same time. c. cylinder b. prove your answer carefully!