posted by poul .
A 45 kg crate is placed on an inclined ramp. When the angle the ramp makes with the horizontal is increased to 22 deg , the crate begins to slide downward.
1-What is the coefficient of static friction between the crate and the ramp?
2-At what angle does the crate begin to slide if its mass is doubled?
mu=tanTheta at the point of sliding.
notice mass has nothing to do with the angle.