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Question
If 784 J of work was done in lifting a 20 kg mass, calculate the height through which it was lifted. (g = 9.8 m/s2)
Solution
Mass of the box (m) = 20 kg
Acceleration due to gravity (g) = 9.8 m/s2
Work done against gravity (W) = 784 J
Let the height above the ground be (h)
So, W = m × g × h
So, height can be calculated as,
`h = W/(m xx g)`
So ,
`h = 784/(20 xx 9.8) m`
= `784/196 m`
= 4 m
So the body is lifted to a height of 4 m.
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