Question

A block weighs W is held against a vertical wall by applying a horizontal force F. The minimum value of F needed to hold the block where it is

$assume:\mu <1$

• A. Less than W
• B. Equal to W
• C. Greater than W
• D. Data is insufficient

Answer 1

The correct option is C

Greater than W

Here applied horizontal force F acts as normal reaction. For holding the block
Force of friction = Weight of block
$f=W\Rightarrow \mu R=W\Rightarrow \mu F=W$
$\Rightarrow F=\frac{W}{\mu }$
As $\mu <1\therefore F>W$