A 20 kg box on a horizontal frictionless surface is pushed with a force of 60 N. What is its acceleration?

A 20 kg box on a horizontal frictionless surface is pushed with a force of 60 N. What is its acceleration?

• A. 4 m/s^2
• B. 3 m/s^2
• C. 2 m/s^2
• D. 5 m/s^2

Answer: (B)

Newton's second law says acceleration equals net force divided by mass. On a frictionless horizontal surface, the push is the only horizontal force, so the net force is 60 N. With a mass of 20 kg, the acceleration is a = F/m = 60 / 20 = 3 m/s^2, in the same direction as the push. If there were friction, you’d subtract the friction force from the push before dividing by the mass.

Newton's second law says acceleration equals net force divided by mass. On a frictionless horizontal surface, the push is the only horizontal force, so the net force is 60 N. With a mass of 20 kg, the acceleration is a = F/m = 60 / 20 = 3 m/s^2, in the same direction as the push. If there were friction, you’d subtract the friction force from the push before dividing by the mass.