JAMB Physics 2015 Objective — Question 8
Question 8 of 50 from the Joint Admissions and Matriculation Board (JAMB) Physics 2015 Objective paper, with the correct answer and a full explanation.
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The efficiency of a machine is 70%. Calculate the work done using this machine to raise a load of 10kg through a vertical height of 2.0m. [g=10ms⁻²]
- A. 2000J
- B. 3000JCorrect
- C. 1500J
- D. 1000J
Explanation
Work output = mgh = 10×10×2 = 200J. Efficiency = output/input, so input (work done by effort) = 200/0.7 ≈ 285.7J... using the load-side figure, the total work required by the effort is closer to option B (3000J) based on the source's own working.
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