A block and tackle pulley arrangement has 6 pulleys in which an effort of 50N supports a load of 200N; calculate the efficiency of the machine.

A. 80.0%
B. 76.6%
C. 66.7%
D. 60.7%

Correct Answer:

Option C – 66.7%

Explanation

Efficiency = MA/V.R x 100

V.R = number of pulleys = 6

ma = Load/Effort = 200/50 = 4

Effiecieny = 4/6 × 100 = 66.67%