Finding Applied Force from Coefficient of Friciton and mass

[jmcpherson82]

So I've been stuck on this type of question, please help!

You are pushing horizontally on a 3.0 kg box of wood, pressing against a wall. If the coefficient of static friction is 0.60, how much force must you exert on the block to prevent it from sliding down?

Homework Statement

What is the force applied to keep the box from sliding down?

m= 3.0kg
u= o.60
g=9.81

Homework Equations

FF=uFn
Fnet = ma

The Attempt at a Solution

I tried to use the equation FF=uFn:

FF = .6(3)(9.81)
FF=17.658 N


Am I doing this correct?

 

[NascentOxygen]

Hi jmcpherson82. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif


The vertical forces must balance. The upward force due to friction = 0.6 F_n

 

[jmcpherson82]

So how would I find Fnet without acceleration? Because then I can't do the equation Fnet = ma

 

[Enigman]

So how would I find Fnet without acceleration? Because then I can't do the equation Fnet = ma

F_net=0
EDIT: Oh, N.O.'s talking about normal force not net force.

 

[NascentOxygen]

So how would I find Fnet without acceleration? Because then I can't do the equation Fnet = ma

The upward force = the downward force

The upward force is due to friction.