1–41. With a block and tackle the effort has to move 125 feet in order to raise a load 25 feet. The  friction is so great that it takes a force of 75 pounds to lift a load of 300 pounds. The  actual  mechanical advantage is 1. five 2. two 3. three 4. four 1-42. The  theoretical  mechanical advantage  of  a  differential  pulley, such as the one pictured in figure 1M, depends upon the 1. difference  in  diameters  of  the t w o  t o p  p u l l e ys 2. sum of diameters of the two top pulleys 3. length of the chain 4. difference  in  diameters  of  the two small pulleys 1-43. In  the  differential  pulley  pictured in figure 1M, if the radius of the small pulley at the top is 3 inches,    the radius of the large pulley at the top is 4 inches, and the radius of the pulley at the bottom is 2 1/2 inches, the theoretical  mechanical  advantage  is 1. 8 2. 9 3. 30 4. 36 1-44. Why  is  the  actual  mechanical advantage  of  the  differential pulley  of  textbook  figure  2–11 never so great as the theoretical mechanical advantage of the pulley? 1. Part of the effort applied to the chain is used to overcome the  frictional  resistance  of the  pulley’s  moving  parts 2. The diameter of C is between those of A and B 3. The diameter of A is greater than that of B 4. The length of the chain fed down is greater than the length of the chain fed up 1-45. A wheel and axle can rotate clockwise  or  counterclockwise  about an axis to provide a mechanical advantage or an increase in speed. 1. True 2. False 1-46. The  mechanical  advantage  of  a  wheel and axle depends upon the 1. amount of force applied and the size of the wheel 2. size of the wheel and the amount  of  the  resistance 3. ratio of the radius of the wheel to which force is applied to the radius of the axle on which it turns 4. length of the axle 7