If the net force on a 5 kg block is 0 N, what is its acceleration?

• A. 1 m/s^2
• B. -1 m/s^2
• C. 2 m/s^2
• D. 0 m/s^2

Answer: (D)

When the net force on an object is zero, there is no unbalanced force to change its motion. Newton’s second law says F_net = m a. With F_net = 0 and mass m = 5 kg, the equation becomes 0 = (5 kg) a, so the acceleration a must be 0. The mass doesn’t affect this result; even a heavy block won’t accelerate without a net force. This means the velocity stays constant—if it was at rest, it stays at rest; if it was moving, it keeps moving at the same speed in the same direction. So the acceleration is 0 m/s^2.