A machine is used to lift a load of 20 N through a height of 10 m. if the efficiency of the machine is 40%, how much work is done?
- 80 J
-
500 J
- 300 J
- 120 J
The correct answer is: B
Explanation
Efficiency = \( \frac{\text{work output}}{\text{work input}} \times \frac{100}{1} \)= 40 = \( \frac{20 \times 10 }{x} \times \frac{100}{1} \)
= 500J
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