A machine uses \( 400J \) energy input and produces \( 320J \) useful output. Determine efficiency.
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Correct Answer: Option B
Explanation:
Efficiency: \( \eta = \dfrac{Useful\ output}{Input} \times 100 \) \( \eta = \dfrac{320}{400} \times 100 \) \( \eta = 80\% \) Therefore, efficiency is \( 80\% \).
Efficiency: \( \eta = \dfrac{Useful\ output}{Input} \times 100 \) \( \eta = \dfrac{320}{400} \times 100 \) \( \eta = 80\% \) Therefore, efficiency is \( 80\% \).