A block of mass 2 kg on a horizontal surface experiences a constant horizontal force of 10 N. If μk = 0.3, what is the acceleration?

A block of mass 2 kg on a horizontal surface experiences a constant horizontal force of 10 N. If μk = 0.3, what is the acceleration?

• A. ≈ 2.06 m/s^2
• B. ≈ 1.02 m/s^2
• C. ≈ 3.12 m/s^2
• D. ≈ 4.12 m/s^2

Answer: (A)

When a mass on a horizontal surface is pulled, its acceleration comes from the net horizontal force acting on it. The friction force opposes motion and, for kinetic friction, has a magnitude μk times the normal force. On a horizontal surface, the normal force is mg, so the friction is f = μk mg. Here, m = 2 kg, g ≈ 9.8 m/s^2, μk = 0.3. So f = 0.3 × 2 × 9.8 ≈ 5.88 N. The net horizontal force is the applied force minus friction: 10 − 5.88 ≈ 4.12 N. Applying Newton’s second law, acceleration a = Fnet / m ≈ 4.12 / 2 ≈ 2.06 m/s^2 in the same direction as the applied force.

When a mass on a horizontal surface is pulled, its acceleration comes from the net horizontal force acting on it. The friction force opposes motion and, for kinetic friction, has a magnitude μk times the normal force. On a horizontal surface, the normal force is mg, so the friction is f = μk mg.

Here, m = 2 kg, g ≈ 9.8 m/s^2, μk = 0.3. So f = 0.3 × 2 × 9.8 ≈ 5.88 N. The net horizontal force is the applied force minus friction: 10 − 5.88 ≈ 4.12 N. Applying Newton’s second law, acceleration a = Fnet / m ≈ 4.12 / 2 ≈ 2.06 m/s^2 in the same direction as the applied force.