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 accelerationdue to gravity is g calculate the minimum force required to be applied by the finger to hold the block against the wall ?

A block of mass M is held against a rough vertical wall by pressing it

1.	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 accelerationdue to gravity is g calculate the minimum force required to be applied by the finger to hold the block against the wall ?
Answer» SOLUTION :Let `F` be the force APPLIED by the finger on the block `N` is NORMAL REACTION of the wall on the block `Mg` is weight of block acting vertically downwards. `F` is the force of friction between the wall and the block which acts upwards as shown in The block will not fall, if `f = mg ` ` MU N = mg , or mu F = mg , or F = (Mg)/(mu) ` .