In a wheel and axle mechanism the diameters of the wheel and axle are 40cm...

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

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Correct Answer: Option B

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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