Question

The figure below shows a hydraulic press supporting a load F.

1. What properties of liquids make them suitable for use in hydraulic machines such as the one above? 
2. If A and a are areas of cross-section of the pistons, and the lengths of the arm are as given, find:
   • The force Fa 
   • The mechanical advantage
   • The efficiency of the machine
   • State two reasons why the efficiency of a pulley system is always less than 100%

Answer 1

1.   
   • Incompressible
   • Non-errosive
2.   
   1.   
      • Fa/0.01 = 700/0.2
        Fa = 35N
        Fo x 1 = Fa x 0.2
        Fo = 35 x 0.2
        =7N
         
      • M.A = L/E
        700/7
        M.A = 100
         
      • VR = V.Rl x VRh
        V.R = 100
        0.2/0.01 x 1/0.2
        M.A/V.R x 100%
        100/100 x 100%
         
      •   
        • Part of the applied effort is raising the blocks
        • Some energy is overcoming friction between the moveable parts