Later, applied force, Fa = F, then fs also increases but only up to a certain limit. As soon as Fa becomes greater than fs, the ball starts to move.
fs acts when a body is at rest. Hence called Static friction o
fs max ∝ N
Limiting value of fs depends on Normal reaction, and is independent of the area of contact
fs max = constant * N
fs max = μs N where μs is the coefficient of static friction This coefficient depends on the nature of surfaces in contact. o
According to the Law of Static friction, Static friction is always less than or equal to the limiting value of fs
fs =< fs max
fs max = μs N
fs =< μs N