Physics
Grade-9
Easy

Question

A device gives out 500 J of heat energy as useful work. Determine the energy supplied to it as input if its efficiency is 40%.

  1. 1000 J
  2. 1250 J
  3. 1500 J
  4. 2000 J

hintHint:

  • Efficiency (%) = (useful energy output ÷ energy input) × 100

The correct answer is: 1250 J


    • Efficiency (%) = (useful energy output ÷ energy input) × 100
    • 40 equals fraction numerator 500 over denominator I n p u t end fraction cross times 100
    • I n p u t equals fraction numerator 500 cross times 100 over denominator 40 end fraction equals 1250 space J

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