Question

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

• A. less than W.
• B. equal to W.
• C. greater or equal W.
• D. Data is insufficient

Answer 1

The correct option is C greater or equal W.

The Normal force here is $F$, so the maximum static friction force is $\mu \times F$

$\mu \le 1$.

So as to prevent slipping, $\mu \times F\ge W\Rightarrow F\ge W/\mu \ge W$