Question detail
A machine uses 500 J of energy input and produces 400 J of useful energy output. What is the efficiency of the machine?
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. 0.8
- B. 80%
- C. 0.4
- D. 40%
Answer
80%
Explanation
The correct option is "80%". 80% is right because it directly matches Energy transfers in a system: State that energy can be transferred usefully, stored or dissipated but cannot be created or destroyed.. The other options are less suitable because they change the required Physics relationship, confuse the relevant energy store or use a distractor that does not answer the question.
Common mistake
Misunderstanding Energy Conservation
Students often think that energy can be created or destroyed in a system.
Remember that energy cannot be created or destroyed; it can only be transferred, stored, or dissipated.
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