A horizontal force of 3,000,000 dynes can keep a 50 kg mass in uniform motion. What is the coefficient of the kinetic friction? At what angle must the plane be tilted to allow the mass to slide?
friction=mu(mg)
3E8dynes*1E-5N/dyne=mu*50*g
solve for mu, the coefficent of friction.
Now on a tilt:
force gravity down the plane: mgSinTheta
force normal to the plane: mgCosTheta
friction force=mu*force normal
so if you tilt it to sliding,
forcedownplane=friction
mgsinTheta=mu*mgCosTheta
tanTheta=mu
theta=arctan mu