A crate slides down a ramp at angle 48 degree to horizontal. The coefficient of limiting friction is 0.48. Find the options for the acceleration of the crate down the ramp.
The maximum friction force opposing motion down the ramp, with a static friction coefficient of 0.48, is M g 0.48 cos 48 = 0.32 M g. That is less than the downward component of gravity, M g sin 48 = 0.74 M g
Therefore sliding will begin, and the speed will accelerate.