WAEC Physics 2022 Objective — Question 12
Question 12 of 50 from the West African Examinations Council (WAEC) Physics 2022 Objective paper, with the correct answer and a full explanation.
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The efficiency of a wheel and axle is 100% and the ratio of their radii is 5:1. Calculate the effort required to lift a load of mass 20kg using this machine. [g=10 m s⁻¹]
- A. 20 N
- B. 20 N B. 20 N C. 40 N
- C. 40 NCorrect
- D. 100 N
Explanation
Load = mg = 20×10=200N. Velocity ratio = 5. At 100% efficiency, Mechanical Advantage = Velocity Ratio = 5. Effort = Load/M.A = 200/5 = 40N.
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