JAMB Physics 2011 Objective — Question 11
Question 11 of 49 from the Joint Admissions and Matriculation Board (JAMB) Physics 2011 Objective paper, with the correct answer and a full explanation.
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A machine is used to lift a load of 20 N through a height of 10m. If the efficiency of the machine is 40%, how much work is done by the effort?
- A. A. 300 J
- B. B. 120 J
- C. C. 80 J
- D. D. 500JCorrect
Explanation
Workdone by load = 20x10 = 200J. Efficiency = (Workdone by load/Workdone by effort)x100%. 40% = (200/Workdone by effort)x100%. Workdone by effort = (200x100)/40 = 500J.
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