Question

An athlete is working out in the weight room. He steadily holds 50 kilograms above his head for 10 seconds. Which statement is true about this situation?

A.
The athlete isn’t doing any work because he doesn’t move the weight.
B.
The athlete isn’t doing any work because he doesn’t hold the weight long enough.
C.
The athlete is doing work because he prevents the weight from falling downward.
D.
The athlete is doing work because 50 kilograms is a significant load to lift.

Answer 1

Answer:

A. The athlete isn’t doing any work because he doesn’t move the weight.

Explanation:

We must remember the definition of work, which says that work is equal to the product of mass by the distance displaced. In this case, the athlete only does work when he lifts the weight from the ground to the point where he holds the weight suspended.

So when he's holding the weight, he doesn't do any work.