Gravitational Field question

1. May 25, 2005

MiniTank

I am having some difficulty with this question:
A satellite is in orbit around Earth at an altitude of 3700 km. How much must its speed increase, in km/h, to escape the Earth's force of gravity?

2. May 25, 2005

whozum

Whats Earth's escape velocity?
What velocity is it orbitting at if its at that altitude?

3. May 25, 2005

MiniTank

Earth's escape velocity = 1.12 x 10^4 m/s
and the velocity at that altitude is what im having tourble with

4. May 25, 2005

whozum

Find the gravitational potential energy at that altitude. What doy ou know about the satelite's KE if it remains at that point?

5. May 25, 2005

MiniTank

i think i get what your saying ..

Ek = 1/2 |Eg|
$$\frac{1}{2}mv^2 = \frac{1}{2}\frac{GMm}{r}$$
$$v=\sqrt{\frac{GM}{r}}$$

after i find that .. do i subtract that velocity from the escape velocity of earth?

Last edited: May 25, 2005
6. May 25, 2005

whozum

Fix your tex tags, slash them the other way, /tex

7. May 25, 2005

whozum

You've got all youj need to solve the problem.

8. May 25, 2005

MiniTank

alright thanks ... appreciate it