# Orbit change of the satelite

1. Dec 17, 2003

### jazzchan

if i want to find the supplied energy when the satelite's orbit changed, do i need to find the its velocity or only find its K.E. ??

thanks..

2. Dec 17, 2003

### Staff: Mentor

Consider the total energy, PE + KE.

3. Dec 17, 2003

### jazzchan

would u mind to tell me more ??

4. Dec 17, 2003

### Staff: Mentor

Why don't you explain the problem you are trying to solve? A satellite in orbit has a certain total energy, which depends on the radius of the orbit. To change the orbit, you must add or subtract energy.

5. Dec 17, 2003

### jazzchan

my problem is one satellite is changed its orbit from 200 km to 3000 km above the earth and from the energy was supplied.

First may i need to fidn the velocity change, then find P.E. ??

6. Dec 17, 2003

### enigma

Staff Emeritus
Last edited by a moderator: Apr 20, 2017
7. Dec 17, 2003

### Staff: Mentor

I take it that your problem is to find the additional energy that must be supplied to a satellite changing from a low orbit to a higher orbit, right?

Since I don't know what you are supposed to know about orbits, I'm not sure what to tell you yet. Tell me how you will find the speed (or KE) of the new orbit and we'll go from there.

To work this kind of problem, you'll have to know about the law of gravity and gravitational PE, and about centripetal acceleration.

8. Dec 17, 2003

### jazzchan

sorry !!! i give a mistake...
let me say again....

A satellite is uniform circular motion in an orbit 200 km above the surface of the earth. if the satellite change its orbrit to 3000 km above the earth , how much energy must be supplied ??

9. Dec 17, 2003

### Staff: Mentor

I understood your problem correctly. So tell us what you've done so far.