A motor transfers 500 J of energy and 400 J is useful. What is the efficiency?
Answer and explanation
Correct answer: D. 80 percent, found by dividing useful energy by total energy
- Step 1: Efficiency = useful output / total input. Step 2. 400 / 500 = 0.8. Answer: 80 percent, found by dividing useful energy by total energy. Why not the others: Energy is conserved, but not all of it is useful.
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