What is the formula for the laws of static friction?

The laws of static friction are,

• When two surfaces are in contact , the frictional force is always tangential to contacting surfaces in a direction opposite to that in which the body tends to move.
• The limiting force of static friction is directly proportional to normal reaction between two surfaces in contact.
• The force of static friction depends on nature and materials of surface.
• The coefficient of static friction is independent of the area and shape of the contacting surfaces.

The formula for law of static friction is given as,

  F_S = µ_s N      ——— where F_S=Force of static friction, µ_s= coefficient of static friction and N=Normal force

The formula for coefficient of static friction is given as,

µ_s = F_S / N