the magnitude of the joint reaction at O2

Question

 An instantaneous configuration of a four-bar mechanism, whose plane is horizontal, is shown in the figure below. At this instant, the angular velocity and angular acceleration of link Q₂ A are ω = 8 rad/s and α = 0, respectively, and the driving torque (T) is zero. The link Q₂ A is balanced so tht its centre of mass falls at O₂.

 

 

at the same instant, if the component of the force in joing A and AB is 30N, then the magnitude of the joint reaction at O₂

      (a) is zero                                                            (b) is 30 N

      (c) is 78 N

      (d) cannot be determined from the given data