Q: In figure a body A of mass m slides on plane inclines at angle θ_{1} to the horizontal and μ is the coefficient of friction between A and the plane. A is connected by a light string passing over a frictionless pulley to another body B, also of mass m, sliding on a frictionless plane inclined at an angle θ_{2} to the horizontal. Which of the following statements are true?

(a) A will never move up the plane

(b) A will just start moving up the plane when $\large \mu = \frac{sin\theta_2 -sin\theta_1}{cos\theta_1} $

(c) For a to move up the plane, θ_{2} must always be greater than θ_{1}

(d) B will always slide down with constant speed

Ans: (b) & (c)