Question

A box rests on a frictionless countertop. 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?

We know the force of the boy on the box is equal in magnitude to the force of the box on the boy, because of Newton’s third law.

a) We know the weight and normal force are equal in magnitude because the box is in equilibrium.

b) We know the weight and normal force are equal in magnitude because of Newton’s third law.

c) We know the force of the boy on the box is equal in magnitude to the force of the girl on the box, because the box is in equilibrium.

Answer 1

The statement regarding the forces being equal in magnitude because the box is in equilibrium is false. Equilibrium means the net force is zero, not necessarily that individual forces are equal.

Step-by-step explanation:

The statement that the force of the boy on the box is equal in magnitude to the force of the girl on the box, because the box is in equilibrium, is false. The concept of equilibrium in physics states that an object is in equilibrium when the net force acting on it is zero. If we have a box on a frictionless surface with two forces acting in opposite directions and the box remains stationary, then it's correct to say the net force is zero.

However, this does not inherently mean the magnitudes of the two forces are equal, as they might be at different angles or involve more than just two forces in equilibrium. For instance, if there's another force acting on the box from a different direction, such as a downward gravitational pull, the horizontal forces could be unequal but still result in a state of equilibrium when all forces are considered.