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: 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