In: Physics
8. Determine the desired quantity in each of the following collisions: (a) A student of mass 60kg sits on a rolling chair (assume no friction with the ground). He pulls out a fire extinguisher and fires 2kg of material at a velocity of 8m/s. How fast is he moving after this process? (b) A 90kg astronaut is traveling through space at a rate of 2m/s. He is holding a 5kg mass as he travels. How fast would he have to throw this mass in order to come to rest? (c) A box of mass 20kg slides across an icy floor at a rate of 5m/s. In order to stop it, we slide smaller boxes of mass of 0.8kg towards it at a rate of 1m/s. How many boxes must collide with (and stick to) it before it comes to a stop? (d) A football player with mass 70kg runs towards another at a rate of 4m/s. Realizing he’s about to get walloped, the second player runs towards the first at a rate of 2m/s. If the second player has a mass of only 50kg, what is the velocity of the pair after the collision? (e) Three billiard balls travel along a table. The first is moving rightwards with a speed of 2m/s, the second is moving leftwards with a speed of 2m/s, and the middle one lies halfway between the first two. What is the velocity of the ball in the middle after the collision?
(f) Alice, with a mass of 60kg, jumps upwards off the Earth. At the moment of her jump, how fast does she move the Earth in the opposite direction? (The mass of the earth is about 5.972 · 1024kg)