fig 4 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 system is 40% then the value of W is
Attached Figure / Diagram
A
28.0N
B
48.0N
C
50.0N
D
288.0N
Verified Correct Answer: C.
Physical Principles & Numerical Solution
Efficiency = \(\frac{M.A\times100}{V.R}\)
V.R = 6
40= \(\frac{M.A\times100}{6}\)
M.A = \(\frac{6 \times40}{100}\)
M.A = 2.4
M.A= \(\frac{L}{E}\)
E= \(\frac{120}{2.4}\)
E = 50
Source: WAEC / JAMB / NECO Classroom Archive (Record #41655)