A box sits on a countertop,stationary.A boy pushes horizontally to the right on the box,and a girl pushes on it to the left,yet it remains stationary.Which of the following statements is false?
A) We know the force of the boy on the box is equal in magnitude to that of the girl on the box because the box is in equilibrium.
B) We know the force of the boy on the box is equal in magnitude to that of the box on the boy because of Newton's third law.
C) We know the weight and normal force are equal in magnitude because the box is in equilibrium.
D) We know the weight and normal force are equal in magnitude because of Newton's third law.

Question

Quizplus · Accepted Answer

Option A is correct. The box is stationary at the position it is placed and the forces from the boy and girl are equal and opposite, thus their magnitudes too are equal. This is the requirement for equilibrium.
Option B is correct. According to Newton's third law, the force of the boy on the box is equal in magnitude and opposite in direction to the force of the box on the boy, hence the option is correct.
Option C is correct. The box is stationary, thus the normal force and weight must be equal, as required by equilibrium.
Option D is false. The weight and normal force are not equal due to Newton's third law. The weight force acting downwards on the box is balanced by the equal and opposite normal force acting upwards on the box due to the countertop. The two are not related by Newton's third law, as they act on different objects.

A Box Sits on a Countertop,stationary