Question

In which of the following cases is work being done on an object?
Suspending a heavy weight with a strong chain
Carrying a box down a corridor
Pushing against a locked door
Pulling a trailer up a hill

Answer 1

Pulling a trailer up a hill is the only case where work is being done

In the first case, there is no motion, so there is no work done

In the second case, the force and motion are perpendicular, so no work is done

In the third case, no motion is being done, so no work is done