1.

The escape velocity from earth is v_(e). A body is projected with velocity 2v_(e). With what constant velocity will it move in the inter planetary space ?

Answer»

`v_(e)`
`sqrt(2)v_(e)`
`sqrt(3)v_(e)`
`sqrt(5)v_(e)`

Solution :`U_(i)+K_(i)=U_(f)+K_(f)`
`rArr-(GMm)/(R)+(1)/(2)m(2v_(e))^(2)=0+(1)/(2)MV^(2)`
or `-(GM)/(R)+2v_(e)^(2)=(1)/(2)V^(2)`
or `-(2GM)/(R)+(8GM)/(R)=v^(2)`
or `v=sqrt((6GM)/(R))=sqrt(3((2GM)/(R)))=sqrt(3(2gR))=sqrt(3)v_(e)`.


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