Question

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​

Answer 1

Explanation:

according to equations of motion,

V^2 - U^2 = -2gs (since body is vertically projected upwards)

since body is moving to certain height and stops.,final velocity of body is zero.

so,

${u}^{2} = 2gs$

$u = \sqrt{2 \times 1 0 \times 15r| }$

$u = 10 \sqrt{3r}$

Answer 2

Answer:(15GM/8R) ^1/2

Explanation:U(i) +K(i) =U(f) +K(f)

-GM/R +1/2XM(u) ^2 = -GM/(15R +R) + 0

u^2= 15GM/8R

u =(15GM/8R) ^1/2 (ans)