Physics
Grade-9
Easy
Question
A construction worker puts 20 J of energy in to one strike of his hammer on the head of a nail. The energy transferred to the act driving the nail in to the wood is 8.0 J. What is his efficiency of hammering?
- 32%
- 160%
- 1/32%
- 1/160%
The correct answer is: 32%
- Efficiency (%) = (useful energy output ÷ energy input) × 100
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