If a machine exerts a force of 250 N on an object and no work is done, what must have occurred?
A) The machine has broken
B) The object has not moved
C) The object has gained momentum
D) The object has moved, but then stopped

A prisoner pushes on the prison wall trying to escape. He is unable to get the wall to move. Describe the work done by the prisoner.
A) The prisoner does no work because he applied no force.
B) The prisoner does a lot of work because the wall is heavy
C) The prisoner does work because extends a lot of effort
D) The prisoner does no work because the wall goes no distance

A 3.0-kg cart rolls down a hill. Assume that the height of the cart changes from a maximum of 4.0 meters at the top of the hill to 0.0 meters at the bottom. The speed of the cart changes from 0.0 m/s to 3.0 m/s. How much kinetic energy does the cart have when it is half way down the hill?
A) 6.0J
B) 12.0J
C) 58.8J
D) 117.6J