The diagram above illustrates a block ans tackle pulley system in which an effort E supports a load of 100.0N. If the efficiency of the machine is 75%, calculate the value of E
A.
22.2N
B.
38.0N
C.
67.0N
D.
75.0N
Correct answer is A
Given; VR = 6, e = 75%, MA = ?
e = \(\frac{\text{MA}}{\text{VR}} \times \frac{100}{1}\)
MA =\(\frac{75 \times 6}{10}\)
MA = \(\frac{9}{2}\)
MA = \(\frac{L}{E} = \frac{100}{E}\)
\(\frac{9}{2} = \frac{100}{E}\)
9E = 100
E = \(\frac{200}{9}\)
= 22.2N