Question detail
A machine has a total energy input of 200 J and produces 150 J of useful work. Calculate the efficiency of the machine as a percentage.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Conservation and dissipation of energy
Question
A machine has a total energy input of 200 J and produces 150 J of useful work. Calculate the efficiency of the machine as a percentage.
Answer
75%
Explanation
This question tests the ability to calculate efficiency, highlighting the relationship between useful output and total input energy. This answer is linked to Energy transfers in a system because it applies the learning objective: Use the term wasted energy to describe energy transferred in less useful ways.. It shows the Physics relationship clearly and keeps energy, power, work done and efficiency terms distinct where they appear.
Common mistake
Misunderstanding Wasted Energy
Students often confuse wasted energy with energy that is simply lost, thinking it disappears rather than being transferred to less useful stores.
Clarify that wasted energy is energy that is transferred in ways that are not useful for the intended purpose, but it is still present in the system.
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