Calculating Coefficient of Kinetic Friction from Given Forces

AI Thread Summary
To calculate the coefficient of kinetic friction for a 23.0 kg block, a horizontal force of 60.0 N is needed to maintain constant speed, indicating this force equals the kinetic friction. The static friction is determined using the 76.0 N force required to initiate motion. The friction force can be calculated using the formula: friction force = weight x coefficient of kinetic friction. By substituting the correct values, the coefficient of kinetic friction can be accurately determined. The key takeaway is that the force required to maintain constant speed directly corresponds to the kinetic friction acting on the block.
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A 23.0 kg block is initially at rest on a horizontal surface. A horizontal force of 76.0 N is required to set the block in motion. After it is in motion, a horizontal force of 60.0 N is required to keep the block moving with constant speed. Find the coefficients kinetic friction from this information.

my attempt:
After the block is in motion 60N is required to prevent it from accelerating.
Therefore what is left over must be used to overcome friction which is 16N.
Friction force = weight x coefficient of kinetic friction
16N=23x9.8 x ck
ck=.070
But this is incorrect.
What am i doing wrong?
 
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60N is the force required to prevent it from accelerating, this is the same force to overcome friction. 16N isn't anything in this problem, it's just the difference between the force required to overcome static friction and the force required to overcome kinetic friction.

Replace 16N with 60N in your calculations and try again.
 
When friction force and the accelerative force are equal speed is constant. Anything extra will cause the body to accelerate so the accelerative force isn't overcoming friction.
60n is used to determine the static friction.
 
as you say you need the same force as friction to stay at constant velocity.

The question tells you there there is 60 N of friction when moving.

76 N is used to determine static friction.
 
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