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JAMB Physics 1984 Question 20

Question 20

Simple Machines

A plane inclined at an angle of 30° to the horizontal has an efficiency of 60%. The force parallel to the plane required to push a load of 120 N uniformly up the plane is

  1. A.60 N
  2. B.100 N
  3. C.120 N
  4. D.200 N
  5. E.240 N
Show the answer and explanation

Answer: B (100 N)

Explanation

VR = 1/sin 30° = 2. MA = efficiency × VR = 0.6 × 2 = 1.2. Effort = 120 ÷ 1.2 = 100 N.