What is the efficiency of a machine that has a work input of 130 ft. lb. and a work output of 39 ft. lb. ?

30%

Explanation

Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine.

\(\text { Efficiency }=\frac{\text { Work }_{\text {out }}}{\text { Work }_{\text {in }}} \times 100=\frac{39 f t . l b .}{130 f t . l b .} \times 100=30 \%\)

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