---
title: "Skater 1, who has a mass of 100 kg, and Skater 2, who has a mass of 50 kg, are initially at rest on a horizontal ice rink where friction is negligible. Skater 1 pushes Skater 2, causing both skaters to move away from each other. While the skaters are in contact and pushing, how do the magnitude of the force Skater 1 exerts on Skater 2 (F12) and the magnitude of the force Skater 2 exerts on Skater 1 (F21) compare, and how do the magnitudes of their accelerations (a1 and a2) compare?"
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url: "https://nerd-notes.com/ubq/109497/"
date_modified: "2026-03-25T04:12:15+00:00"
---

# Skater 1, who has a mass of 100 kg, and Skater 2, who has a mass of 50 kg, are initially at rest on a horizontal ice rink where friction is negligible. Skater 1 pushes Skater 2, causing both skaters to move away from each other. While the skaters are in contact and pushing, how do the magnitude of the force Skater 1 exerts on Skater 2 (F12) and the magnitude of the force Skater 2 exerts on Skater 1 (F21) compare, and how do the magnitudes of their accelerations (a1 and a2) compare?

Skater 1, who has a mass of 100 kg, and Skater 2, who has a mass of 50 kg, are initially at rest on a horizontal ice rink where friction is negligible. Skater 1 pushes Skater 2, causing both skaters to move away from each other. While the skaters are in contact and pushing, how do the magnitude of the force Skater 1 exerts on Skater 2 (F12) and the magnitude of the force Skater 2 exerts on Skater 1 (F21) compare, and how do the magnitudes of their accelerations (a1 and a2) compare?

![Two skaters on a flat horizontal surface. Skater 1 is larger and represented on the left, pushing with hands extended against Skater 2, who is smaller and on the right. Arrows point away from the point of contact to indicate the direction of the forces they exert on each other.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1774411935-BVFsXz.jpg)

- **A.** F12 is greater than F21 because Skater 1 has more mass, and a1 is less than a2 because of Skater 1's greater inertia.
- **B.** F12 is equal to F21 because they form a Newton’s Third Law interaction pair, and a1 is less than a2 because Skater 1 has more mass.
- **C.** F12 is equal to F21 because they form a Newton’s Third Law interaction pair, and a1 is equal to a2 because the forces acting on them are identical.
- **D.** F12 is less than F21 because Skater 2 must exert a larger force to overcome the greater inertia of Skater 1, and a1 is less than a2.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/109497/*