A block and tackle system has six pulleys. a force of 50N applied to it lifts a load of weight W. If the efficiency of the system is 40%, calculate W
-
A.
300N -
B.
200N -
C.
140N -
D.
120N
Correct Answer: Option D
Explanation
M.A = (frac{E times V.R}{100} = frac{40 times 6}{100} = frac{12}{5})
W = M.A x effort
= (frac{12}{5} times 50 = 120N)