Finding Applied Force from Coefficient of Friciton and mass

The downward force is due to the weight of the box (mg).In summary, the question asks how much force must be exerted on a 3.0 kg box with a coefficient of static friction of 0.60 to prevent it from sliding down a wall. The solution involves using the equation FF = uFn and setting the upward force due to friction equal to the downward force due to the weight of the box. This results in a final answer of 17.658 N.
  • #1
jmcpherson82
2
0
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?
 
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  • #2
Hi jmcpherson82. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]


The vertical forces must balance. The upward force due to friction = 0.6 Fn
 
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  • #3
So how would I find Fnet without acceleration? Because then I can't do the equation Fnet = ma
 
  • #4
jmcpherson82 said:
So how would I find Fnet without acceleration? Because then I can't do the equation Fnet = ma

Fnet=0
EDIT: Oh, N.O.'s talking about normal force not net force.
 
  • #5
jmcpherson82 said:
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.
 

1. What is the equation for finding applied force using coefficient of friction and mass?

The equation for finding applied force is F = μmg, where F is the applied force, μ is the coefficient of friction, m is the mass of the object, and g is the acceleration due to gravity.

2. How do you calculate the coefficient of friction?

The coefficient of friction can be calculated by dividing the force of friction by the normal force (Ff/Fn).

3. What factors affect the coefficient of friction?

The coefficient of friction is affected by the type of materials in contact, the roughness of the surfaces, and the presence of lubrication or other substances.

4. Can the coefficient of friction be greater than 1?

Yes, the coefficient of friction can be greater than 1. This indicates a very high level of friction between the two surfaces.

5. How does the mass of an object affect the applied force needed to overcome friction?

The greater the mass of an object, the greater the applied force needed to overcome friction. This is because the weight of the object increases with mass, and therefore the force of friction also increases.

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