5-55. The exercise machine consists of a rigid bar. pin connected to the frame at A.As the man pushes upon the bar it stretches the rubber band BC- If the stiffness of the rubber band is k = 500Ib/ft,determine the applied vertical 229 5-57. A 10-kN load is suspended from the boom at D. Determine the force in the hydraulic cylinder BC and the pin reaction at A. force F needed to hold the bar in the position 8 = 30°.The rubber band is unstretched when 8 = 0p