How Do Spacecraft Velocities Change in Different Orbits?

[Kelseywelsey]

Homework Statement

A spacecraft of mass 1000 kg is in an elliptical orbit about the earth. At point A the spacecraft is at a distance of 1.2 x 10^7 meters form the center of the Earth and its velocity ( 7.1 x 10^3 m/s) is perpendicular to the line connecting the center of the Earth to the spacecraft . Mass of the earth= 6.0 x 10^24 and radius= 6.4 x 10^4. I need to find the speed of the spacecraft if it is in a CIRCULAR orbit and the minimum speed of the craft at pt. A if it is to escape completely from the earth.

Homework Equations

V at point B= 2400 m/s

The Attempt at a Solution

So far, I've figured that the mechanical energy is 8.1 x 10^9 J
Angular momentum= 8.52 x 10^13
and speed at a point directly across from A
V= 2.4 x 10^3

 

[Mindscrape]

Alright, so more than just telling us what numbers you have, you should go over some concepts and why you chose these numbers.

What kind of questions do you have that could be answered and potentially helpful to you solving the problem?

More importantly, what is it that is keeping the spacecraft in orbit? How do you think that case will be broken?