Question

Minimum horizontal force $F=120N$ is required to keep the block of mass $4kg$ at rest.

• A. coefficient of friction between the block and the wall is $\frac{1}{4}$
• B. coefficient of friction between the block and the wall is $\frac{1}{3}$
• C. force exerted by the wall on the block is $120N$
• D. force exerted by the wall on the block is $40\sqrt{10}N$

Answer 1

The correct option is B coefficient of friction between the block and the wall is $\frac{1}{3}$

Given that,

Force = $120N$

Now, the frictional force is balanced by gravity as

$\mu F=mg$

$\mu =\frac{4\times 10}{120}$

$\mu =\frac{1}{3}$

Hence, the coefficient of friction between the block and the wall is $\frac{1}{3}$