Question

A projectile is fired vertically from Earth's surface with an initial speed of 9.9 km/s. Neglecting air drag, how far above the surface of Earth will it go?

Answer 1

Answer:

5000 km    

Explanation:

At the highest point, the velocity would be zero. v = 0

Initial speed, u = 9.9 km/s

Use the third equation of motion:

$s =\frac{v^2-u^2}{2a}$

a= -g (acceleration due to gravity acts downwards)

substitute the given values:

$s =\frac{0^2-(9.9\times 10^3)^2}{-2\times 9.8}\\ s=5\times 10^6 m = 5000km$