A machine takes in 800 J of energy and gives out 320 J of useful energy. What is its efficiency?
Answer and explanation
Correct answer: B. 40%
- Step 1: Efficiency .
- Step 2: .
Answer
40%.
Why not the others: 60%: that is the percentage of energy wasted. 480%: it subtracts the energies and reports joules as a percentage.
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