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With what velocity should a body be thr...

With what velocity should a body be thrown up so that it rises to a height equal to the radius of the earth (`g=10ms^(-2)` at the surface) ?

A

`8000 ms^(-1)`

B

`6400ms^(-1)`

C

`1600ms^(-1)`

D

`1000 ms^(-1)`

Text Solution

Verified by Experts

The correct Answer is:
A
K.E. = change in P.E.
`(1)/(2)mv^(2)=(-GMm)/(2R)+(GMm)/(R )`
`v^(2)=(GM)/(R )=(gR^(2))/(R )`
`v=sqrt(gR)=sqrt(10xx6.4xx10^(6))=800m//s`
So correct choice is (a).
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