Topic: Engineering Mechanics
Two blocks A and B of 1 kg each are kept on a flat surface, one above other. The coefficient of friction between each contacting pair is 0.2. If the lower block is pulled with a horizontal force F, the minimum value of F for which the slip occurs between the blocks is nearly
- A. 5.9 N
- B. 4.9 N
- C. 18.4 N
- D. 0
Answer: A. 5.9 N
Explanation: Friction occurs at both the top interface and the ground interface. Normal force at top R_A = 1g. Normal force at bottom R_B = (1+1)g. F = mu*R_A + mu*R_B = 0.2*(3*1*9.81) = 5.886 N, which is approx 5.9 N.