A wheel and axle of radii 800mm and 200mm respectively is used to raise a body of weight 800N by the application of 250N. Calculate the efficiency of the machine
-
A.
85% -
B.
80% -
C.
60% -
D.
20%
Correct Answer: Option B
Explanation
V.R = (frac{R}{r} = frac{800}{200} = 4)
M.A = (frac{L}{E} = frac{800}{250} = 3.2)
y = (frac{M.A}{v.R} times frac{100}{1} = 80)%