. Draw a diagram of combination of three movable pulleys and one fixed pulley to lift up a load
Draw a diagram of combination of three movable pulleys and one fixed pulley to lift up a load. in the diagram, show the directions of load, effort and tension in each strand. Find: (i) the mechanical advantage, (ii) velocity ratio and (iii) the efficiency of the combination in ideal situation.
Best Answer
Diagram:
Tension T1 in the string passing over the pulley A is given as
2T1 = L or T1 = L/2
Tension T2 in the string passing over the pulley B is given as
2T2 = T1or T2 = T1/2 = L/22
Tension T3 in the string passing over the pulley C is given as
2T3 = T2orT3 = T2/2 = L/23
In equilibrium, T3 = E
E =L/23
Mechanical advantage = MA = L/E = 23
As one end of each string passing over a movable pulley is fixed, so the free end of string moves twice the distance moved by the movable pulley.If load L moves up by a distance x, dL = x, effort moves by a distance 23x, dE = 23x
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