Question

A $8kg$ block is at rest on a horizontal floor. If you push horizontally on the $8kg$ block with a force of $20N$, it just starts to move.

What is the coefficient of static friction?

• A. $0.2$
  
• B. $0.255$
  
• C. $0.3$
  
• D. $0.6$
  

Answer 1

The correct option is B $0.255$

Let ${\mu }_s$ be the coefficient of static friction between the block and the floor.

$F={\mu }_{s}mg$

We get ${\mu }_s=\frac{F}{mg}$

$\therefore$ ${\mu }_s=\frac{20}{8\times 9.8}=0.255$