A machine has an efficiency of 75%. The work done when the machine is used to raise a load of 50 kg through a vertical distance of 6 m is [Take g =…
Source: JAMB · 2024
A machine has an efficiency of 75%. The work done when the machine is used to raise a load of 50 kg through a vertical distance of 6 m is [Take g = 10ms⁻²]
Explanation
Useful work output = weight × height = 50 × 10 × 6 = 3000 J.
Efficiency = useful work output ÷ work input. So 0.75 = 3000 ÷ work input.
Work done by the machine (input) = 3000 ÷ 0.75 = 4000 J.
The 3000 J is only the useful part. The rest is lost to friction and heat in the machine.
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