A spaceship is launched into a circular orbit close to the earth's surface . What additional velocity has now to be imparted to the spaceship in the orbit to overcome the gravitational pull. Radius of earth `= 6400 km`, `g = 9.8m//s^(2)`.

Options

A. `11.2kms^(-1)`
B. `8kms^(-1)`
C. `3.2kms^(-1)`
D. `1.414xx8kms^(-1)`

Answer

C

Explanation

`V_(e)=11.2km//s`
`(mv^('2))/R=(GMm)/(R^(2))`
`v^('2)=(GM)/(R^(2))R`
`v'=sqrt(10xx6400000)=8km//s`
Therefore the additional velocity `=(11.2-8)=3.2km//s`