JAMB - Physics (2018 - No. 10)

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?

28.0
48.0N
233.0N
50.0N

Explanation

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

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