A 12 kg crate is at rest on the floor. Two equal masses are subjected to the forces shown. The forces have the same magnitude, and floor is frictionless. Each box is displaced by the same distance x to the right.
More work is done on the left box because the horizontal force is bigger.
More work is done on the left box because the normal force is smaller. More work is done on the right box because the horizontal force is smaller. More work is done on the right box because the normal force is bigger. The same amount of work is done on both boxes. The coefficient of friction between the tires and the road is 0.85.