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JAMB Physics 2014 Question 15

Question 15

Simple Machines

A wheel and axle is used to raise a load whose weight is 800 N when an effort of 250 N is applied. If the radii of the wheel and axle are 800 mm and 200 mm respectively, the efficiency of the machine is

  1. A.80%.
  2. B.85%.
  3. C.87%.
  4. D.90%.
Show the answer and explanation

Answer: A (80%.)

Explanation

VR = 800 ÷ 200 = 4 and MA = 800 ÷ 250 = 3.2. Efficiency = 3.2/4 × 100% = 80%.