Exam-style question
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A mechanical system has a total energy input of 500 J and a useful energy output of 400 J. Calculate the efficiency of the system.
Model answer
What a good answer should say
- The efficiency of the system is 80%.
Explanation
Why this works
This question tests the understanding of efficiency in mechanical systems. The efficiency is calculated using the formula: efficiency = (useful output / total input) x 100.
Substituting the values gives (400 J / 500 J) x 100 = 80%. This demonstrates the ability to apply the concept of efficiency correctly.
Common mistake
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