Question

A force of 5 N is required to move an object from rest. The value of static friction (${\mu }_s$) is:

• A. 5 N
• B. f > 5 N
• C. f < 5 N
• D. 10 N

Answer 1

The correct option is A 5 N

Static friction force acts in response to a force trying to cause a stationary object to start moving. If there is no such force acting on an object, the static friction force is zero. If there is a force trying to cause motion, the static friction force will increase up to a maximum value before it is overcome and motion starts.

$f_{static}$ $\le$ ${\mu }_{static}$ $\times$ $F_{normal}$

value of static friction varies from zero to maximum values of force when it just starts moving.

Here 5N force is required to just move the object from rest.

therefore static force is equal to 5N.

Option A is correct.