Question

Question on static friction

Answer 1

If you have two blocks of the same material with one block having a mass twice that of the other, on an inclined plane, they will both reach their maximum value of static friction at the same angle. Why is this so?

Answer 2

because the coefficient of friction is a function of the nature of the contact between the blocks and the incline, not their masses.

Further, if you write down the equations of motion of the block and ask when exactly is the incline (angle) at which they start to move, you will see that m cancels from the equation. There is an m with the gravitational force, and an m from the frictional force as
\[ F_f = \mu N \] and N = mg cos(angle)