The block B is suspended from a single inextensible cable that is attached to the block at E, wraps around three pulleys, and is tied to the back of a truck. The truck starts from rest when L is zero, and moves forward with a constant acceleration (to the right) of 0.5 m/s When L = 0, points C and D are at the same elevation, and the vertical distance between the pulley center at A and D is H-6 m. Neglect the size of the pulleys in the calculation. L H C E B A D