Finding Applied Force from Coefficient of Friciton and mass

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Homework Help Overview

The discussion revolves around determining the applied force necessary to prevent a wooden box from sliding down a wall, given its mass and the coefficient of static friction. The subject area includes concepts of friction, forces, and equilibrium in mechanics.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate the force of friction using the coefficient of static friction and the normal force. Some participants question how to determine the net force without knowing the acceleration, while others clarify the distinction between net force and normal force.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the forces involved. There is an exchange of ideas regarding the balance of forces, but no consensus has been reached on the approach to find the applied force.

Contextual Notes

Participants are navigating the constraints of the problem, including the lack of acceleration information and the definitions of forces involved in the scenario.

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


The vertical forces must balance. The upward force due to friction = 0.6 Fn
 
Last edited by a moderator:
So how would I find Fnet without acceleration? Because then I can't do the equation Fnet = ma
 
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.
 
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.
 

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