---
title: "A person holds a book at rest a few feet above a table. The person then lowers the book at a slow constant speed and places it on the table. Which of the following accurately describes the change in the total mechanical energy of the Earth–book system?"
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url: "https://nerd-notes.com/ubq/91351/"
date_modified: "2025-05-08T03:12:11+00:00"
---

# A person holds a book at rest a few feet above a table. The person then lowers the book at a slow constant speed and places it on the table. Which of the following accurately describes the change in the total mechanical energy of the Earth–book system?

A person holds a book at rest a few feet above a table. The person then lowers the book at a slow constant speed and places it on the table. Which of the following accurately describes the change in the total mechanical energy of the Earth–book system?

- **A.** The total mechanical energy is unchanged, because there is no change in the book’s kinetic energy as it is lowered to the table.
- **B.** The total mechanical energy is unchanged, because no work is done on the Earth–book system while the book is lowered.
- **C.** The total mechanical energy decreases, because the person does positive work on the book by exerting a force that opposes the gravitational force.
- **D.** The total mechanical energy decreases, because the person does negative work on the book by exerting a force on the book in the direction opposite to its displacement.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/91351/*