Coefficient of static friction and minimum horizontal force

[kamalpreet122]

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

 

[SammyS]

F_nis the unknown.

F_f must be equal to the weight.

 

[kamalpreet122]

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