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JAMB Physics 1998 Question 12

Question 12

Simple Machines

In a wheel and axle mechanism, the diameters of the wheel and axle are 40 cm and 8 cm respectively. Given that the machine is 80% efficient, what effort is required to lift a load of 100 N?

  1. A.20 N
  2. B.25 N
  3. C.50 N
  4. D.80 N
Show the answer and explanation

Answer: B (25 N)

Explanation

Velocity ratio = 40/8 = 5. Mechanical advantage = 0.8 × 5 = 4. Effort = load ÷ MA = 100 ÷ 4 = 25 N.