The earth is assumed to be a sphere of raduis `R`. A plateform is arranged at a height `R` from the surface of the `fv_(e)`, where `v_(e)` is its escape velocity form the surface of the earth. The value of `f` is

Options

A. `(1)/(3)`
B. `(1)/(2)`
C. `sqrt(2)`
D. `(1)/(sqrt(2)) `

Answer

D

Explanation

`v_(e) = sqrt((2GM)/(R))`
and `v_(e). = sqrt((2GM)/(R + h)) = sqrt((2GM)/(R + R)) = (v_(e))/(sqrt(2)) " " therefore f = (1)/(sqrt(2))`.