Question

The cable cars in San Francisco are pulled along their tracks by an underground steel cable that moves along at 9.5 mph. The cable is driven by large motors at a central power station and extends, via an intricate pulley arrangement, for several miles beneath the city streets. The length of a cable stretches by up to 100 ft during its lifetime. To keep the tension constant, the cable passes around a 1.5-m-diameter "tensioning pulley" that rolls back and forth on rails, as shown in the figure. A m 2200 kg block is attached to the tensioning pulley's cart, via a rope and pulley, and is suspended in a deep hole. (Figure 1) You may want to review (Pages 169- 172) nday