---
title: "A wooden crate of mass M is sliding at a constant velocity across a horizontal surface while being pulled by a horizontal rope. A student then places a heavy metal block on top of the crate while it is still in motion. Which of the following describes the change, if any, in the magnitude of the kinetic friction force exerted by the surface on the crate?"
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url: "https://nerd-notes.com/ubq/109458/"
date_modified: "2026-03-23T01:19:09+00:00"
---

# A wooden crate of mass M is sliding at a constant velocity across a horizontal surface while being pulled by a horizontal rope. A student then places a heavy metal block on top of the crate while it is still in motion. Which of the following describes the change, if any, in the magnitude of the kinetic friction force exerted by the surface on the crate?

A wooden crate of mass M is sliding at a constant velocity across a horizontal surface while being pulled by a horizontal rope. A student then places a heavy metal block on top of the crate while it is still in motion. Which of the following describes the change, if any, in the magnitude of the kinetic friction force exerted by the surface on the crate?

![A rectangular crate labeled M is on a flat horizontal line representing the floor. A horizontal arrow labeled v points to the right. A metal block is shown hovering just above the crate, ready to be placed on top of it. A horizontal rope is attached to the right side of the crate.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1774228748-aWFLF9.jpg)

- **A.** The kinetic friction force increases because the normal force exerted by the surface on the crate increases.
- **B.** The kinetic friction force increases because the coefficient of kinetic friction increases when more mass is added.
- **C.** The kinetic friction force remains the same because the crate is still moving at a constant velocity.
- **D.** The kinetic friction force remains the same because the materials in contact have not changed.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/109458/*