Minimum Force to Make an Object Move

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To determine the minimum force required to move a 6 kg object on a surface with a coefficient of friction of 0.8, the maximum static friction force (Fsmax) must be calculated. The normal force (Fn) equals the weight of the object, which is 58.8 N. The force of friction (Ff) is then calculated as 47.088 N, using the formula Ff = coefficient of friction * weight. To initiate movement, any applied force must exceed this frictional force. The discussion emphasizes the importance of recognizing static equilibrium conditions in solving such problems.
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Homework Statement


A 6 kg object sits on a horizontal surface with coefficient of friction = .8. What is the minimum force (not necessarily horizontal) necessary to make the object slide?

Homework Equations


Fsmax = u * Fn
where Fsmax is the force that must be overcome to make an object move, u is the coefficient of friction, and Fn is the normal force.

The Attempt at a Solution


I was just wondering if this seemed correct:
Fg = -58.8 N (mass * g) so
Fn = 58.8 N
I'm not clear on when exactly one can make the assumption that Fg = Fn
but then using that value of Fn I calculated Fsmax, so the minimum force necessary to make the block move is any force greater than Fsmax.
 
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You need to overcome the force of friction.

The force of friction is
Ff=(coefficent of friction)(weight of object in Newtons)
Ff=(.8)(6*9.81)
Ff=(.8)(58.86)
Ff=47.088N

I think :D
 
uchicago2012 said:
I'm not clear on when exactly one can make the assumption that Fg = Fn

One can always make the assumption that, if the acceleration in some coordinate direction is zero, then by Newton's second law, the sum of all forces acting along that direction must be zero.

This condition for static equilibrium is the foundation for all introductory statics problems.
 
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