A wheel and axle is used to raise a load of 500 N by the application of an effort of 250 N. If the radii of the wheel and the axle are 0.4 cm and 0.1 cm respectively, the efficiency of the machine is
A
20 %
B
40 %
C
50 %
D
60 %
Verified Correct Answer: C.
Physical Principles & Numerical Solution
Efficiency = M.A/V.R X 100/1 M.A = Load/Effort = 500/250
= 2
V.R. = radius of wheel/radius of axle = 0.4/0.1 = 4.
therefore Efficiency = 2/4 x 100/1 = 50 %
Source: Myschool Past Questions Archive (Record #9562)