The efficiency of a wheel and axle is 100% and the ratio of their radii is 5:1. calculate the effort required to lift a load of mass 20kg using this machine, [g = 10 m s−2]

A. 20N
B. 25N
C. 40N
D. 100N

Correct Answer:

Option C = 40N

Explanation

VR = 5:1 or 5

Load = 20kg or 200N

MA = 200E
Efficiency% = MAVR∗100
100% = 2005E∗100
5E = 200

E = 40