A box is pushed across a rough horizontal floor by a force acting parallel to the floor in the direction of motion. A force doing negative work on the body is
A) gravity.
B) the applied force.
C) friction.
D) the normal reaction force of the floor upward on the body.
E) a fictitious force.

Question

Quizplus · Accepted Answer

Friction always acts in the opposite direction of motion, so it does negative work on the box as it is pushed forward.

A Box Is Pushed Across a Rough Horizontal Floor by a Force