A pulley stems has an efficiency of 65.1%. If you perform 350 J of work, how much useful work does the pulley perform?

A. 350 J

B. 301 J

C. 228 J

D. 122 J

Answer;

C. 228 Joules

Explanation;

Efficiency of a machine is the energy or work output, divided by the energy or work input, and expressed as a percentage. An ideal machine would have an efficiency of 100%.

Efficiency = (work output/work input) * 100%

work input = 350 joules, efficiency = 65.1%

Work output = 350 j * 65.1/100

= 227.85

≈ 228 Joules