Work

“Work is the transfer of energy to a body by the application of a force that causes the body to move in the direction of the force.

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Definition of Work in Physics

Question:

A construction worker lifts a heavy cinder block 1 m off the ground, holds it in place for 3 s, then sets it back down in the same place. Describe the forces doing work on the block and the net work on the block throughout this action.

Answer:

While lifting the block, the worker does positive work on the block while gravity does negative work on the block. The net work while lifting the block is positive. When the worker is holding the block, no forces do work on the block and no net work is done on the block. While lowering the block, the worker does positive work while gravity does negative work on the block. The net work on the block while it is lowered is negative. The total net work on the block is zero because the net displacement is zero.