A particle is fired vertically upwards from the surface of earth and reaches a height 6400km. Find the initial velocity of the particle if R = 6400km and g at the surface of earth is `10m//s^2`

Explanation

`1/2"m"upsilon^2=(mgh)/([1+(h//R)])`
here h = R = 6400 km and `g = 10 m//s^2`
so `upsilon^(2)=gh` , i.e. `upsilon=sqrt(10xx6400xx10^(3))=8km //s`