1.

A satellite of mass m revolving in a circular orbit of radius 3 R_Earound the earth (mass of earth is Me and radius is R_E ). How much excess energy be spent to bring it to orbit of radius 9 R_E ?

Answer»

`(GM_Em)/(3R_E)`
`(GM_Em)/(18R_E)`
`(3GM_Em)/(2R_E)`
`(GM_Em)/(9R_E)`

Solution :`implies` Total energy of SATELLITE `|E| = (GM_Em)/R`
`:.` Energy at `r = 3R_E`
`|E_1|=(GM_Em)/(2(3R_E))=(GM_Em)/(6R_E)`
and Energy at `r = 9R_E`
`|E_2|=(GM_Em)/(2(9R_E))=(GM_Em)/(18R_E)`
`:.` EXCESS energy from going `3R_E " to " 9R_E`
`DeltaE=E_1 -E_2`
`= (GM_Em)/(6R_E) - (GM_Em)/(18R_E)`
`= (2GM_Em)/(18R_E)`
`= (GM_Em)/(9R_E)`


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