Question

Coefficient of friction between 5 kg and 10 kg blocks is 0.5. If friction between them is 20 N. What is the value of force being applied on 5 Kg block.

• A. 10 N
• B. 30 N
• C. 20 N
• D. 40 N

Answer 1

Answer: (C)

20 N

FBD is shown in figure above.
If 20 N is the friction force between masses 5 kg and 10 kg, the value of force applied on 5 kg is,
We know that the coefficient of friction between the 5 kg and 10 kg block is 0.5. So the applied force at which the 5 kg block starts moving would be $\mu mg=0.5\times 5\times 10=25N$. So for the given frictional force of 20 N, the block is still in equilibrium and the applied force thus is 20 N.