Consider a system to be one train car moving toward another train car at rest. When the train cars collide, the two cars stick together. What is the total momentum of the system after the collision?
800 kg • m/s
1,600 kg • m/s
2,400 kg • m/s
4,000 kg • m/s

Apulley with a mechanical advantage of 5 will require you to pull times the amount of rope. a. 1/5 b. 5 c. 10 d. 15

Chemical energy is a form of energy. a. heat b. kinetic c. potential d. electromagnetic

The star betelgeuse is about 600 light-years away. if it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space. b. we'll know it immediately because it will be brighter than the full moon in the sky. c. we won't know about it until 600 years from now. d. none of the above.