A block <span lan

Here, the force by the finger is given by “F”, the normal force is “N”, the frictional force is “f” and the weight of the body is acting downwards given by “Mg”.

We first balance the horizontal forces:

Now we balance the horizontal forces. Here, we have to stop the block from falling. So the acceleration should be zero.
—————(1)

The frictional force is given by:

—————(2)

Substituting (2) in (1)