Question

A 25 kg box rests without sliding on a loading ramp at an angle of 30 degrees. What is the coefficient of friction between the box and the ramp?
I know the answer is .58 but I'm not sure how to do this.

Answer 1

\[F _{static}=\mu mg\]
on a horizontal surface

Answer 2

on an angle...
\[F _{static}=\mu mgcos \Theta\]
not sure where to go from here without additional info. nothing else was given?

Answer 3

I figured it out. tanΘ=tan(30)=.577

Answer 4

0_o huh