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A 12-kg box is pushed at constant speed (the box is already moving at this constant speed at t = 0 s and continues to do so even after the animation ends) as shown in the animation (position is given in meters and time is given in seconds). The hand pushes on the box at an angle of 60° from the vertical. Note that there are four forces acting on the box: gravity, the force of the hand, the normal force, and friction. Restart.

During the animation,

1. Is the work done on the box by the external force (hand) positive, negative, or zero?
2. Is the work done on the box by the normal force positive, negative, or zero?
3. Is the work done on the box by gravity positive, negative, or zero?
4. Is the work done by friction (done on the box and the table) positive, negative, or zero?
5. Is the total work done on the box positive, negative, or zero?

Problem authored by Melissa Dancy.