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

Explanation

Here mass of the block = M
Coefficient of friction between the block and the wall `=mu`
Lef F be force required to hold the block against the wall

Figure show that weight of block mg is in downward direction and friction force is in upward direction for equilibrium
f = mg
F=N
Frictional force F =`mu N`
Comparing (1) and (2)
mF = Mg
`F=(MG)/( mu)`