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JAMB Physics 2018 Paper

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Question : 46

Total: 87

A 20kg mass is to be pulled up a slope inclined at 30° to the horizontal. If efficiency of the plane is 75%. The force required to pull the load up the plane is J [g=10ms

^{-2}

]

87N
73.5N
133.3N
533.2N

Solution:

V. R = $\frac{1}{\sin\theta}$

m = 20kg

V.R = $\frac{1}{\sin 30}$

= 2

Efficiency = 75%

Load = mg

= 20 x 10 = 200N

Efficiency = $\frac{M.A}{V.R} \times 100$

75/100 = $\frac{M.A}{2}$

M .A = $\frac{75 \times 2}{100}$

M. A = 1.5

Since M. A. = $\frac{\text{Load}}{\text{Force}}$

Force = $\frac{200}{1.5}$

= 133.3N

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