In a wheel and axle mechanism the diameters of the wheel and axle are 40cm...
PHYSICS
JAMB 1998
In a wheel and axle mechanism the diameters of the wheel and axle are 40cm and 8cm respectively. Given that the machine is 80% efficient, what effort is required to lift a load of 100N?
- A. 20N
- B. 25N
- C. 50N
- D. 80N
Correct Answer: B. 25N
Explanation
Efficiency = \(\frac{\text{work done by hand}}{\text{work done by effort}}\)
80 = \(\frac{100{\times 8}}{E {\times} 40}\) x \(\frac{100}{1}\)
E = 25N
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