In order to uncoil electrical wire from a spool fixed to a truck, a worker drives to the left with a speed of v_A = 4 m/s. At the same time, a second worker holds the cable as he walks to the right. Knowing that at the instant shown the thickness of wire on the spool is 50 mm and that the 0.6-m-radius spool has an angular velocity of 8 rad/s, determine 

(a) The instantaneous center of rotation of the spool, 

(b) The velocity of point D on the spool, 

(c) The speed of the second worker B.

Fig. P15.78 and P15.79 Hidbitkil VB