A block of mass 10 kg is accelerating at 2 m/s^2 on a horizontal surface under an applied force of 50 N. What is the magnitude of the frictional force opposing its motion? MCQ with Answer and Explanation

A block of mass 10 kg is accelerating at 2 m/s^2 on a horizontal surface under an applied force of 50 N. What is the magnitude of the frictional force opposing its motion?
A. 20 N
B. 50 N
C. 70 N
D. 30 N
Answer: Option D
Solution (By JKExamLibrary)
According to Newton's Second Law, the net force on the block is F_net = mass * acceleration = 10 kg * 2 m/s^2 = 20 N. The net force is the difference between the applied forward force and the opposing frictional force (F_net = F_applied - F_friction). So, 20 N = 50 N - F_friction. Solving for friction gives F_friction = 50 - 20 = 30 N.

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