The following parameters of the arrangement of Fig are available: the angle α which the inclined plane forms with the horizontal, and the coefficient of friction k between the body m1 and the inclined plane. The masses of the pulley and the threads, as well as the friction in the pulley, are negligible. Assuming both bodies to be motionless at the initial moment, find the mass ratio m2/m1 at which the body m2
(a) starts coming down;
(b) starts going up;
(c) Is at rest.

Fig. 1.11.