Question

Shani poses as the Statue of Liberty for an art class. She holds a torch above her head with her right hand and a book against her side with her left hand. She holds the pose for ten minutes. At the end of the session, she mentions to her friend that it was a lot of work to pose and that her arms are really tired.

Which describes the work Shani did while she posed?(assume the starting work position is when her hand is already raised )

She did more work with her right hand than with her left because the right was held up higher.
She did no work while she posed because she did not move the torch or the book.
She did work while she posed because she was tired at the end of the session.
She did no work while she posed because she did not exert a force on anything.

Answer 1

Answer: "She did no work while she posed because she did not move the torch or the book."

Reason: In physics mechanical work = force × displacement (F·Δx). While holding the objects stationary her hands exert forces but there is no displacement of the torch or book, so the mechanical work done on them is zero. (Her muscles still used chemical energy and she felt tired, but that is internal biochemical energy expenditure, not mechanical work on the objects.)