A barbell of mass 5 kg is raised to a height of 3 m above the ground. Calculate the work done by the boy. Take acceleration due to gravity $g = 10 m s^{-} 2.$

150 J

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300 J

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-300 J

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- 150 J

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Solution

The correct option is A 150 J
Mass of barbell, m = 5 kg
Height of lift, h = 3 m
Force require to lift the barbell = Weight of the barbell
Weight of the barbell $= m \times g$
$= 5 \times 10 = 50 N$
Work done by boy, $W = F o r c e \times D i s p l a c e m e n t$
$= 50 \times 3 = 150 N m o r J$
Work done is positive as both force and displacemnet are in the same direction.

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A barbell of mass 5 kg is raised to a height of 3 m above the ground. Calculate the work done by the boy. Take acceleration due to gravity g=10 ms−2.

A barbell of mass 5 kg is raised to a height of 3 m above the ground. Calculate the work done by the boy. Take acceleration due to gravity $g = 10 m s^{-} 2.$