Projectile Launch - Using Earth's Radius

[bustin]

1. What is the launch speed of a projectile that rises vertically above the Earth to an altitude equal to 14 R_earth before coming to rest momentarily?

Homework Equations

sqrt{2GM(\\frac{1}{R_e}-\\frac{1}{14R_e})}

The Attempt at a Solution

G= 6.67x10^11
M=5.97x10^24
R_e=6.37x10^6

I get 2988 m/s I know its wrong but I gave it a shot. This is for online homework. Any help would be very nice. Thanks in advance

 

[D H]

What is the total mechanical energy at launch? At maximum altitude? How do these relate?

 

[bustin]

i tried to look into that but I couldn't find much info in my book. could you be more specific?

 

[bustin]

i finally got it. i got 10802 m/s.

thanks for the tip