Question

What is the maximum value of the force F such that the block shown in the arrangement, does not move?

• A. 20 N
• B. 10 N
• C. 12 N
• D. 15 N

Answer 1

The correct option is A 20 N

Maximum value of force applied is equal to its static friction force.

Here, friction force is $f=\mu N$

Here, normal reaction force is : $N=Fsin{60}^0+mg$

Let us balance the force applied in horizontal direction with frictional force

$Fcos{60}^0=\mu (Fsin{60}^0+mg)\frac{F}{2}=\frac{1}{2\sqrt{3}}(\frac{\sqrt{3}F}{2}+\sqrt{3}\times 10)$

We get: $F=\frac{F}{2}+10F=20N$