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A body of mass 10 kg is dropped to the g...

A body of mass 10 kg is dropped to the ground from a height of 10 metres. The work done by the gravitational force is `(g=9.8m//sec^(2))`

A

`-490J`

B

`-980J`

C

`+490J`

D

`+980J`

Text Solution

Verified by Experts

The correct Answer is:
D
Given `: vec( F ) = ( 5 hat(i) +4 hat(j) -3 hat(k))` and `vec(s) = 5 hat(j)`, as it moves 5m along the Y axis
`:. W = vec(F). vec(s) = ( 5 hat(i) + 4 hat(j) -3 hat(k)). ( 5 hat(j))`
`:.` Work done ( W ) `= 20 hat(j) . hat(j) =20 J`
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