Exam-style question
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What is the efficiency of a system that outputs 300 J of useful energy from an input of 600 J?.
- A.50%
- B.75%
- C.100%
- D.25%
Model answer
What a good answer should say
- 50%
Explanation
Why this works
Efficiency is calculated using the formula: efficiency = (useful output / total input) x 100. Substituting the values: efficiency = (300 J / 600 J) x 100 = 50%.
This shows that half of the input energy is converted into useful output.
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