Which statements describe a situation in which work is being done? Check all that apply.

Question

A box is carried up a flight of stairs by a mover.
A box sits on a table waiting to be moved.
Wind blows against a steel table anchored to the ground.
Wind blows a pool chair across the yard.
A weightlifter lifts a barbell off the ground.
A weightlifter holds a barbell above his head.

Answer 1

To determine when work is being done, we can refer to the physics definition of work, which states that work occurs when a force causes an object to move in the direction of that force. Based on this definition, the following statements describe situations in which work is being done:

1. A box is carried up a flight of stairs by a mover. (Work is done as the box is being moved against gravity.)
2. Wind blows a pool chair across the yard. (Work is done as the wind causes the chair to move.)
3. A weightlifter lifts a barbell off the ground. (Work is done as the barbell is moved up against gravity.)

The following situations do not involve work being done:

• A box sits on a table waiting to be moved. (No movement occurs.)
• Wind blows against a steel table anchored to the ground. (No movement occurs since the table is anchored.)
• A weightlifter holds a barbell above his head. (No movement occurs; although force is applied, the barbell is not moving.)

So, the statements that describe a situation in which work is being done are the first, fourth, and fifth statements.