Gpe question (1 Viewer)

[PhysicsMaths]

Explain why the energy needed to place a satellite in orbit is greater than the work required to lift the satellite to the correct height of this orbit.

In other terms,why does it take more energy to put a satellite into orbit at x km altitude than it does just to lift it up to x km?

 

[nightweaver066]

Think orbital velocity.

 

[dan964]

exactly. not to mention you aren't just going straight up but curved

 

[InteGrand]

In other terms,why does it take more energy to put a satellite into orbit at x km altitude than it does just to lift it up to x km?

Because to actually put it in orbit, you need to get it there, PLUS give it the kinetic energy required for that orbit.

At a distance of , for uniform circular motion, equating centripetal force with gravitational force, , from which we get that , which is the extra energy you must give to place the satellite in orbit compared to just lifting it to the correct height (assuming it starts with 0 kinetic energy. (Here, M was the mass of the planet, m was the mass of the satellite, and K was kinetic energy.)

 

[anomalousdecay]

The work required to lift the satellite to the orbit is just the change in potential energy.

That is,

To place a satellite into the orbit, the satellite must have a sufficient orbital speed to keep it in that orbit. Hence, as InteGrand said:

Because to actually put it in orbit, you need to get it there, PLUS give it the kinetic energy required for that orbit.

At a distance of , for uniform circular motion, equating centripetal force with gravitational force, , from which we get that , which is the extra energy you must give to place the satellite in orbit compared to just lifting it to the correct height (assuming it starts with 0 kinetic energy. (Here, M was the mass of the planet, m was the mass of the satellite, and K was kinetic energy.)

This is an explain question. Hence, state the cause and effect, then make a reasoning for this as appropriate to the question.