Suppose you carry a bag of groceries weighing 115 N from your kitchen, a distanc

Question

Suppose you carry a bag of groceries weighing 115 N from your kitchen, a distance of 34 m, without raising or lowering the bag. What is the work done by the force you exert on the bag? 0 J 3910 J 1525 J 7820 J 4723 J A young boy of mass m = 25 kg sits on a coiled spring that has been compressed to a length x = 0.4 m shorter than its uncompressed length and then held at this length. Suddenly the spring is released, and the boy flies vertically into the air. He reaches a maximum distance h = 0.5 m above his initial position. The spring is ideal and massless and we ignore the air friction. 766 N/m 1531 N/m 613 N/m 1509 N/m 1276 N/m

Explanation / Answer

This is, in a way, a trick question.

The definition of work done is the force times displacement and the force must be in the direction of the displacement. Since you apply a force upward, to support the weight of the groceries, and you do not move the bag upward or downward, your force does not do any work. The groceries are moving in a horizontal direction into your house, the applied force and the displacement are actually perpendicular to each other, that is, in a direction in a completely different component.

Thus the work done by your force is 0 J, which is choice a.

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