The velocity ratio and efficiency of a system of pulleys are 6 and 80% respectively. How much effort is required to lift a load of mass 120kg with this system? (g=10ms−²)

A. 25N
B. 90N
C. 96N
D. 250N
E. 960N

Correct Answer:

Option D – 250N

Explanation

Efficiency = M.A/V.R x 100%

= 80/100
= 120 x 10/E

E = 250N