The maximum static frictional force is

$A$ block of mass $M$ is held against a rough vertical wall by pressing it with a finger. If the coefficient of friction between the block and the wall is $\mu$ and the acceleration due to gravity is $g$,calculate the minimum force required to be applied by the finger to hold the block against the wall.

$A$ $10\, kg$ block is placed on a horizontal surface as shown. If an external horizontal force $F = 50\, N$ is applied,find the friction force acting on the block. (Take $g = 10\, m/s^2$)

Impending relative motion is opposed by which type of friction?

$A$ block of weight $W$ is held against a vertical wall by applying a horizontal force $F$. The minimum value of $F$ needed to hold the block is $[\mu < 1]$.

$A$ box of mass $15 \text{ kg}$ is kept on the floor of a stationary trolley. The coefficient of static friction between the box and the trolley is $0.12$. Keeping the box in a stationary state over the trolley, the maximum acceleration with which the trolley can be moved horizontally in $\text{m s}^{-2}$ is: $(g = 10 \text{m s}^{-2})$