A 32 kg box sitting on a ramp has a coefficent of 0.21. If the ramp is raised, at what angle will the box begin slipping?
coefficent of friction?
force downward=Fn*mu=mgCosTheta*mu
force down the ramp= mg*sinTheta
set these two forces equal
mgCosTheta*mu=mgSinTheta
I think you get
tan Theta=mu
check that.