A 100-kg box is placed on a ramp. As one end of the ramp is raised, the box begins to move downward just as the angle of inclination reaches 15 degrees. What is the coefficient of static friction between box and ramp?

Question

A 100-kg box is placed on a ramp.  As one end of the ramp is raised, the box begins to move downward just as the angle of inclination reaches 15 degrees.  What is the coefficient of static friction between box and ramp?

Henry · Accepted Answer

Wb = m * g = 100kg * 9.8N/kg = 980 N.

F1 = 980*sin15 = 253.6 N. = Force parallel to the ramp.
F2 = 980*cosi5 = 946.6 N. = Force perpendicular to the ramp.

Fs = F1 = 253.6 N. @ 15o

u = Fs/F2 = 253.6/946.6 = 0.268

anthony · Answer

whats is the answer