Coefficient of static friction and minimum horizontal force

AI Thread Summary
To determine the minimum horizontal force required to hold a 5.0 kg mass against a wall with a coefficient of static friction of 0.85, the frictional force (Ff) must equal the weight of the mass. The weight is calculated as 49 N (5.0 kg multiplied by the acceleration due to gravity). The frictional force is then calculated using the equation Ff = UFn, resulting in Ff = 0.85 * Fn. The confusion arises because the teacher's answer of 58 N suggests a different interpretation of the normal force (Fn). Ultimately, understanding that the frictional force must counteract the weight is key to solving the problem.
kamalpreet122
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Homework Statement



A 5.0 kg mass is held against a wall with which it has a coefficient of static friction of 0.85. What is the minimum horizontal force required to hold the mass against the wall ?

The teacher said answer is 58 N .. i can't get to that answer..

Homework Equations



Ff = UFn

The Attempt at a Solution



Ff = 0.85(49)
Ff = 41.65

this answer makes sense but for some reason ..the teacher has given us a different answer :S
 
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Fnis the unknown.

Ff must be equal to the weight.
 


yea that makes a lot of sense thanxx a lot :D
 
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