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JAMB Physics 2012 Paper

Question : 9

Total: 42

Solution:

Concept:

Efficiency is the ratio of useful work output to total work input, expressed as a percentage.

Explanation:

Step 1. Calculate the useful work done in raising the load:

W_{\text{output}} = 250 \times 30 = 7500\ \mathrm{J}

Step 2. Determine the total work input by adding the work done against friction:

W_{\text{input}} = 7500 + 1500 = 9000\ \mathrm{J}

Step 3. Apply the efficiency formula:

\text{Efficiency} = \frac{W_{\text{output}}}{W_{\text{input}}} \times 100\% = \frac{7500}{9000} \times 100\% = 83.3\%

Answer:

Option C: 83.3%.

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