The diagram represents a block-and-tackle pulley system on which an effort of 50N is just able to lift a load of weight W. If the efficiency of the machine is 40%. find the value of W

A. 300N
B. 200N
C. 140N
D. 120N
E. 20N

Correct Answer:

Option D – 120N

Explanation

Eff = MA/VR x 100%

40 = MA/60

MA = 240

LE=240/100

W = L = (240 x 50)/100

= 120N