Question detail
A heating system has a total energy input of 5000 J and an efficiency of 0.75. How much energy is wasted?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Conservation and dissipation of energy
Question
- A. 1250 J
- B. 1500 J
- C. 1750 J
- D. 2000 J
Answer
1250 J
Explanation
The correct option is "1250 J". 1250 J is right because it answers the Efficiency objective: Calculate efficiency using useful energy output divided by total energy input.. The distractors are incorrect because they either use the wrong Physics quantity, confuse an energy store with a transfer, or ignore the wording of this question.
Common mistake
Confusing Efficiency Calculation
Students often confuse the formula for efficiency by using total energy output instead of useful energy output.
Remember to use the formula: efficiency = useful energy output / total energy input.
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