Calculating Energy Requirements for Changing Satellite Orbits

[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..

 

[Doc Al]

Consider the total energy, PE + KE.

 

[jazzchan]

would u mind to tell me more ??

 

[Doc Al]

Originally posted by jazzchan
would u mind to tell me more ??

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.

 

[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. ??

 

[enigma]

What do you mean by "energy supplied"?

For orbital transfers, you need to do a http://liftoff.msfc.nasa.gov/academy/rocket_sci/satellites/hohmann.html, and then compute the delta-Vs from that.

Is delta V what you meant by energy supplied?

 

[Doc Al]

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.

 

[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 ??

 

[Doc Al]

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