# PHYSICS

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?

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1. 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

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