7(a).

The spring ABC has a stiffness of 500 N/m and an unstretched length of 6 m. A horizontal force F is applied to the cord which is

attached to the small pulley B so that the displacement of the pulley from the wall is d = 1.5 m. Draw a free-body diagram for the

small pulley B.

Figure 6

- 500 N/m

7(b). The 2-kg block is held in equilibrium by the system of springs. Draw a free-body diagram for the ring at A.

Figure 7

D

c=20 N/m

500 N/m

Figure 8

p=40 N/m

7(c). Blocks D and ♬ weigh 5 lb each and block E weighs 8 lb. The system is in equilibrium at a given sag s. Draw the free-body

diagram for the connecting ring at A and find s. Neglect the size of the pulleys.

-30 N/m