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JAMB Physics 2008 Question 14

Question 14

Simple Machines

The efficiency of the pulley system shown above is 80%. Find the effort E required to lift a load of 1200 N.

Diagram for this question
  1. A.275 N.
  2. B.325 N.
  3. C.375 N.
  4. D.573 N.
Show the answer and explanation

Answer: C (375 N.)

Explanation

The system has 4 pulleys, so VR = 4. MA = 0.8 × 4 = 3.2. Effort = load ÷ MA = 1200 ÷ 3.2 = 375 N.