Question

A block of mass 9.00 kg is pushed up against a wall by a force P that makes a 50.0° angle with the horizontal as shown below. The coefficient of static friction between the block and the wall is 0.245. Determine the possible values for the magnitude of P that allow the block to remain stationary.

So you are pushing a block at an angle of 50° against a vertical wall, to keep it stationary what is Pmin force, and Pmax force (before the block starts moving upwards).

Pmin=?
Pmax=?

Answer 1

Force down = m g

Force up = F sin 50 + .245 F cos 50

so to keep it from falling
F (sin 50 + .245 cos 50) = m g

to start it upwards, reverse the friction force
F (sin 50 -.245 cos 50) = m g

Answer 2

Thank you!!