An object of mass 20kg slides down an inclined plane at an angle of 30 degree to the horizontal. The coefficient of static friction is?

Answer 1

If 30 degrees is the minimum angle that allows slipping to start, then the coefficient of static friction (mu_s) is given by

M*g*sin30 = M*g*mu_s*cos30
mu_s = tan30 = 0.5774

The mass M does not matter.

Angles greater than 30 degrees will also allow slipping.

Answer 2

0.5774

Answer 3

What is the meaning of mus