The diagram shown represents a block-and-tackle pulley system on which an effort of W Newtons supports a load of 120.0N. If the efficiency of the machine is 40, then the value of W is?
A.
28.0
B.
48.0N
C.
233.0N
D.
50.0N
Correct answer is D
Given Data:
Efficiency = 40% Load = 120N, V.R = 6 (Number of Pulleys)
Efficiency = \(\frac{M.A}{V.R} * 100\)
40 = \(\frac{M.A}{6} * 100\)
6 * 40 = 100 M.A
M.A = \(\frac{240}{100}\) → 2.4
Where M.A = \(\frac{Load}{Effort}\)
2.4 = \(\frac{120}{Effort}\)
: Effort = \(\frac{120}{2.4}\) → 50N