Q. A horizontal force $F$ is applied on a block of weight $W$ to hold against a vertical wall. The minimum value of force needed to hold the block if the coefficient of friction of the surface is $\mu$

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A

$\frac{W}{\mu}$

B

$\frac{\mu}{W}$

C

$\mu W$

D

$W$

Solution:

Let $F$ be the normal reaction, then $\mu F=W \quad$
$ \therefore F=\frac{W}{\mu}$

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