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, $\mu \times F\ge W$
$F\ge W/\mu$
so, $F\ge W$