Satellite motion and Moment of Momentum

Click For Summary

Homework Help Overview

The discussion revolves around the motion of a satellite and the concept of moment of momentum, particularly in the context of transitioning between orbits. Participants are examining the relationships between velocity, radius, and forces acting on the satellite.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to apply the cross product of position and momentum to relate the velocities in different orbits, while also considering the effects of an applied force. They express uncertainty about how to proceed with energy relations that involve gravitational constants.
  • Some participants question the clarity of the original poster's question and suggest focusing on the equations of motion for satellites in circular orbits.
  • Others suggest that examining centripetal acceleration and forces in both orbits could provide insight, and they affirm that using angular momentum and energy relations is a valid approach.

Discussion Status

The discussion is ongoing, with participants providing hints and guidance without reaching a consensus. There is an exploration of different aspects of the problem, including the application of angular momentum and energy relations, which may help clarify the original poster's confusion.

Contextual Notes

Participants note the importance of visual aids, as the original poster's image link was initially unclear. There is also an acknowledgment of the gravitational constant's role in the energy relations being discussed.

___
Messages
61
Reaction score
0

Homework Statement



http://img194.imageshack.us/img194/4638/001ofa.jpg

Homework Equations



Not too sure to be honest.

The Attempt at a Solution



Well, r1 cross product m v1 = r2 cross m v2
But, there is a force applied so I have to take that into account.
I was thinking,
The moment of momentum after the thrust = Moment of momentum when it first enters the second orbit

r1 m v1 = r1 m v2

gives
v2/v1 = 7
But I am not being able to take that any further.

I'm trying to use energy relations but it gives me an equation in terms of GM (gravitational constant and mass of planet).

I have no idea where to begin. Maybe you guys could point me to the right direction?
 
Last edited by a moderator:
Physics news on Phys.org
pal, where's your question ?
 
http://img194.imageshack.us/img194/4638/001ofa.jpg

Can the image not be seen? I've scanned the question and posted it there...
I got rid of it and now there's a link.
 
Last edited by a moderator:
Hint: what is the equation of motion for a satellite in a circular orbit?
 
___ said:

Homework Statement



[PLAIN]http://img194.imageshack.us/img194/4638/001ofa.jpg

Homework Equations



Not too sure to be honest.

The Attempt at a Solution



Well, r1 cross product m v1 = r2 cross m v2
But, there is a force applied so I have to take that into account.
I was thinking,
The moment of momentum after the thrust = Moment of momentum when it first enters the second orbit

r1 m v1 = r1 m v2

gives
v2/v1 = 7
But I am not being able to take that any further.

I'm trying to use energy relations but it gives me an equation in terms of GM (gravitational constant and mass of planet).

I have no idea where to begin. Maybe you guys could point me to the right direction?

Use the image feature to get your image to show.
The literal string of characters I used was:
[tex]\text{[PLAIN]http://img194.imageshack.us/img194/4638/001ofa.jpg }[/tex]
 
Last edited by a moderator:
___ said:

The Attempt at a Solution



Well, r1 cross product m v1 = r2 cross m v2
But, there is a force applied so I have to take that into account.
I was thinking,
The moment of momentum after the thrust = Moment of momentum when it first enters the second orbit

r1 m v1 = r1 m v2

gives
v2/v1 = 7
But I am not being able to take that any further.

I'm trying to use energy relations but it gives me an equation in terms of GM (gravitational constant and mass of planet).

I have no idea where to begin. Maybe you guys could point me to the right direction?
What is the centripetal acceleration in each of the circular orbits. How does the centripetal force supplied the planet's gravity compare for the two circular orbits.

Yes, using angular momentum (moment of momentum) may be helpful.

I think using energy relations is a very good idea. Yes, of course it will include GM. That should not be a problem.

You should be able to answer part (d) first. That may be the biggest help of all.


 

Similar threads

  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 2 ·
Replies
2
Views
1K
Replies
5
Views
2K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
10
Views
6K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 7 ·
Replies
7
Views
5K