What is the Magnitude of Force P to Keep a Block Stationary Against a Wall?

[Wild ownz al]

A block of mass 3.00kg is pushed up against a wall by a force of P that makes a 50.0 degree angle with the horizontal (REFER TO PICTURE). The coefficient of static friction between the block and the wall is 0.250. Determine the possible values for the magnitude of P that allow the block to remain stationary.

 

[topsquark]

You have an applied force which has a component in the horizontal direction. You also have a normal force directed in the opposite direction. (Let's say that N is in the negative x direction and the component of the applied force is in the +x.) The sum of these two forces must be 0 N as there is no motion in this direction. This gives you N in terms of the applied force. Thus [math]\sum F _x = -N + F~cos(50) = 0[/math].

What can you say about the vertical (y) direction? Do the same thing. A lot of stuff will cancel out.

By the way, you missed a force on your diagram. There is a friction force acting downward of magnitude [math]f = \mu N[/math].)

See what you can do with this.

-Dan