# Homework Help: General work question

1. Jan 6, 2009

### yoleven

1. The problem statement, all variables and given/known data
If 100 joules of energy is transferred from a mover to a box, does the mover do 100 joules of work on the box or does the box do 100 joules of work on the mover?
Does the box lose energy?

2. Relevant equations
W=F*d

3. The attempt at a solution
I don't think the box loses energy because 100 joules are transferred to it from the mover.
I don't think the box does work on the mover because no movement is indicated.
Same goes for the mover, no work is done because no distance is indicated?

2. Jan 6, 2009

Think of Newton's third law "To every action there is an equal and opposite reaction."

3. Jan 7, 2009

### razored

Don't use the word lose because energy is never "lost"; it is merely converted or transfered.

"I don't think the box loses energy because 100 joules are transferred to it from the mover.
I don't think the box does work on the mover because no movement is indicated.
Same goes for the mover, no work is done because no distance is indicated? "

If there is no displacement, there is no work done(Fd). The box moved since we have done work. I think, that the box did do work on the person. For instance, we know the formula Fd, the force the box did was directed towards the person, but the displacement the other way, so -Fd or -100J. However, the person applied the force in the same direction and displacement was in the same direction hence positive 100J. I hope this is right.