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A man pulls a 50.0 kg box with a rope parallel to the ground. He pulls the box 100.0 m. About how much work has he done?

Question

Help asap? 
 
A man pulls a 50.0 kg box with a rope parallel to the ground. He pulls the box 100.0 m. About how much work has he done?

vincent-lyon.fr · Answer

Not enough information to answer your question.
We need to know the coefficient of friction between the box and the ground.

anonymous · Answer

Work equals the force along a distance. We know the force from gravity, but it doesn't act along the distance pulled. If there are no forces, no work.

anonymous · Answer

There has to be an applied horizontal force, otherwise how would it have moved horizontally?