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A body of mass 1 kg is thrown upwards wi...

A body of mass `1 kg` is thrown upwards with a velocity `20 ms^(-1)`. It momentarily comes to rest after attaining a height of `18 m`. How much energy is lost due to air friction? `(g = 10 ms^(-2))`

A

`20 J`

B

`30 J`

C

`40 J`

D

`10 J`

Text Solution

Verified by Experts

The correct Answer is:
`(1)`
Intial velocity `u = 20 m /s, m = 1 kg`
Kinetic energy = maximum potential energy
Initial kinetic energy = `1/2 xx 1 xx 20^(2) = 200 J`
`Mgh(max) = 200 J`
`therefore h = 20 m`. The height travelled by the body, h. = 18m `Rightarrow` Energy lost =` 200 J - 1 xx10 xx18 J = 20J`
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Knowledge Check

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