Question

38. A body is to be projected vertically upward from
Earth surface to reach a height 15R, where R is the
radius of Earth. The initial velocity required to do so.
is (M is the mass of earth)
15 GM
GM
V16R
GM
5GM
121
(1) V8 R
3 VOR
(4) V SR
li​

Answer 1

Explanation:

since the body is vertically projected upwards

according to equation of motion

V^2 - U^2 = -2gs

where

V = final velocity

U = initial velocity

s = distance it reached = 15R

since it reaches certain height and stopped, the final velocity of that body is zero

so,

-U^2 = -2gs

U^2 = 2×10×15R = 300R

so, U = 10V3R