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JAMB Physics 1991 Question 10

Question 10

Simple Machines

A 20 kg mass is to be pulled up a slope inclined at 30° to the horizontal. If the efficiency of the plane is 75%, the force required to pull the load up the plane is [g = 10 m s−2].

  1. A.13.3 N
  2. B.73.5 N
  3. C.133.3 N
  4. D.533.2 N
Show the answer and explanation

Answer: C (133.3 N)

Explanation

VR = 1/sin 30° = 2, so MA = 0.75 × 2 = 1.5. Effort = 200 ÷ 1.5 ≈ 133.3 N.