The fiqure above 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\(^o\), then the value of W is
A.
28.0N
B.
48.0N
C.
288.0N
D.
50.0N
Correct answer is D
V.E = 6, load = 120N
Efficiency = M.A x \(\frac{1}{V.R}\) x 100%
40 = \(\frac{120}{effort}\) x \(\frac{1}{6}\) x \(\frac{100}{1}\)
Effort = 50N