A 3 kg block on a frictionless horizontal table has a 5 N horizontal force applied. What is the acceleration?

• A. 0.33 m/s^2
• B. 1.67 m/s^2
• C. 5 m/s^2
• D. 8 m/s^2

Answer: (B)

The key idea is Newton's second law: the acceleration a is the net force F divided by the mass m, a = F/m. On a frictionless surface there’s no opposing force, so the applied horizontal force is the net force. With a mass of 3 kg and a force of 5 N, the acceleration is 5/3 ≈ 1.67 m/s^2. The acceleration points in the same direction as the applied force, along the table. This value shows how a given force moves a given mass when there’s nothing to slow it down.