This problem has been bugging me, seeing that my answer seems off. But who knows. Given the following measurements, find the required pushing force needed to keep a book from sliding down the wall. 1. The problem statement, all variables and given/known data M= 2.88kg Coefficient of static friction= .322 2. Relevant equations Seeing that the book can't move, I figured that F=Normal force mg=2.88kg(9.80 m/s^2)=28.2N force of static friction=μsN ƩFx=F-N=0 meaning F=N (Makes sense) ƩFy=mg-fs=0 meaning mg=μs(N) thus, N=(mg/μs) 3. The attempt at a solution I did a simple substitution by setting F=(mg/μs)=(28.2N/.322)=87.6N To me, that answer seems a little high. So, is my reasoning and/or answer correct?