Question

june 2010

1. which body is in equilibrium?

(1) a satellite moving around earth in a circular orbit
(2) a cart rolling down a frictionless incline
(3) an apple falling freely toward the surface of earth
(4) a block sliding at constant velocity across a tabletop

1. a student pulls a 60 - newton sled with a force having a magnitude of 20. newtons. what is the magnitude of the force that the sled exerts on the student?

(1) 20. n (3) 60. n
(2) 40. n (4) 80. n

Explanation:

Step1: Apply Newton's third law

Newton's third law states that for every action, there is an equal and opposite reaction. When the student pulls the sled with a force of \( F = 20\space N\), the sled exerts a force on the student. According to the law, the magnitude of the force that the sled exerts on the student is equal to the magnitude of the force that the student exerts on the sled.

Answer:

A. \(20\space N\)