Question

Brandi poses as Lady Justice for a skit in her government class. She holds a set of scales above her head with her right hand and a sword by her side in her left hand. She holds the pose for 10 minutes. At the end of the skit, she mentions to her friend that it was a lot of work to pose and that her arms were really tired.

Which best summarizes Brandi’s statement about doing work while posing?

She did no work because she did not exert any forces on objects.
She did more work using her right hand than her left because her right hand was higher.
She did no work because she did not move the scales or sword while she posed.
She did work the entire time she posed because she was tired at the end.

Answer 1

She did no work because she did not move the scales or sword while she posed.

Explanation: In physics, mechanical work = force × displacement of the point of application. Although Brandi exerted forces to hold the objects (and her muscles used metabolic energy, making her tired), there was no displacement of the objects while she held them, so no mechanical work was done on them.