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Question
A boy uses a single fixed pulley to lift a load of 50 kgf to some height. Another boy uses a single movable pulley to lift the same load to the same height. Compare the effort applied by them. Give a reason to support your answer.
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Solution
The ratio of load to the effort is called the mechanical advantage.
Mechanical advantage (MA) = `"Load(l)"/"Effort(E)"`
The above equation indicates that 'MA' and 'Effort' are inversely proportional.
The mechanical advantage of the single fixed pulley is 1.
For, single movable pulley = 50 kgf
:. Effort (Esingle fixed pulley) = `"Load"/(MA_"single fixed pulley")`
= `50/1 = 50` kgf
Effort (Esingle fixed pulley) = `"Load"/(MA_"single movable pulley")`
= `50/2 = 25` kgf
Therefore, the boy using a single movable pulley requires lesser effort to lift an equal load of 50 kgf when compared with the effort required by the boy using a single fixed pulley.
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