The static friction force \( f = \mu_s N \) acts to resist the motion of the block.
In this case, the static friction is strong enough to counteract any force attempting to move the block. Since the friction force exceeds the component of gravitational force pulling the block down the incline, the block remains stationary and does not accelerate.
Therefore, the acceleration is zero.
A wooden block of mass M lies on a rough floor. Another wooden block of the same mass is hanging from the point O through strings as shown in the figure. To achieve equilibrium, the coefficient of static friction between the block on the floor and the floor itself is