Physics: Static friction question?

An 78.2 N crate of apples sits at rest on a ramp that runs from the ground to the bed of a truck. The ramp is inclined at 21.1° to the ground.


(a) What is the normal force exerted on the crate by the ramp?


(b) What is the static frictional force exerted on the crate by the ramp?


(c) What is the minimum possible value of the coefficient of static friction?


(d) The normal and frictional forces are perpendicular components of the contact force exerted on the crate by the ramp. Find the magnitude and direction of the contact force.

Physics: Static friction question?
a) N=78.2*9.81*cos(21.1)





b) f=78.2*9.81*sin(21.1)





c) µs=tan(21.1)





d) sqrt(N^2+f^2)


at an angle of


f/N=tan(21.1)





21.1 degrees w/r/t the incline


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