Question

A wheel of radius R and negligible mass is mounted on a horizontal friction less axle so that the wheel is in a vertical plane. Three small objects having masses m, M, and 2M, respectively, are mounted on the rim of the wheel, as shown. If the system is in static equilibrium, what is the value of m in terms of M? 

(A) M/2 

(B) M 

(C) 3M/2 

(D) 2M 

(E) 5M/2

Answer 1

Correct option (C) 3M/2

Applying rotational equilibrium at the center pivot we get:

+mg(R) + Mg(Rcos60°) – 2Mg(R) = 0.

Using cos60° = ½ we arrive at the answer 3M/2