1. Consider a wooden block placed on a horizontal surface as shown in the figure and small horizontal force F is applied to it.
2. The block does not move with this force as it cannot overcome the frictional force between the block and horizontal surface.
3. In this case the force of static friction is equal to F and balances it.
4. The frictional force which balances applied force when the body is static is called force of static friction. In other words, static friction prevents sliding motion.
5. If we keep increasing F, a stage will come
- For F < Fmax, the force of static friction is equal to F.
- when for F = Fmax, the object will start moving.
- For F ≥ Fmax, the kinetic friction comes into play.
6. Static friction opposes impending motion i.e. the motion that would take place in absence of frictional force under the applied force.
