Question

A block of mass m is pressed against a vertical wall with a force F acting at an angle theta. What are the maximum and minimum forces of F that can be applied and still have the block remain stationary?

Answer 1

If theta is the angle above horizontal and there is no friction
then
F sin theta must be = m g
if theta = 0 , F is infinite
if theta = 90 degree, F = m g

Answer 2

oops sorry I forgot to mention express it in terms of m, g, theta, and us ( coefficient of static friction)

Answer 3

to prevent sliding down:
F sin T >/= m g - mu m g cos T

to prevent sliding up
F sin T </= m g + mu m g cos T