Question

If the coefficient of static friction between the block and rough horizontal surface is 0.6 and normal reaction is 100 N. Find the static friction on the block if applied force is 60N.

Answer 1

Static friction is a self-adjusting force.

The limiting value of friction up to which the body stays at rest till it starts moving is given by, F  

s

​  

=μmg

where μ is the coefficient of static friction.

Below that limit, the frictional force is equal to the force applied.

Here F  

s

​  

=0.8×4×10=32N ;   g=10m/s  

2

 

Whereas force applied is 19N less than the limiting value of friction.

Hence Frictional force is 19N