Physics Lesson 10/28

The maximum static friction force relates to the normal force in a similar way as the kinetic friction force.

Remember, the static friction force acts in response to a force trying to cause a stationary object to move.

If there is no such force on the object, the static friction force is 0.

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.

 $F_{f,\ static}\ \le\ \mu_sF_N$  Th

In the equation for the maximum static friction force,  $\mu_s$  is the coefficient of static friction between two surfaces.

The maximum static friction force that must be overcome before motion can begin is $\mu_sF_N$  .