Re: Here's one for Bob (hope it makes your head spin)

re: rocket engines

Another way to look at it is to look at ion engines.

ION engines are essentially glorified cathode ray tubes without a phosphor plate in the front.

A tiny ion is created, and is then accelerated by magnets out of the engine.

for every joule of energy given to that ion, a joule of energy in the opposite direction is given to the "thing" that pushes the ion.

Now, say an ion weights 1 gramme. The ship weighs 1000 kilos (1000*1000 grammes).

To accelerate the ship by an extra 1km/h, you will need to accelerate the ion by 1000*1000 = 1,000,000 km/h.

So, as you push the ion out the back, it also pushes the ship out in the front.

In the case of ion engine, it is essentially magnets which accelerate it.

In the case of a rocket engine, it is pressure differential between the combustion chamber and the outside which accelerates the burning gases out the exhaust. The pressure differential is due to the gases pushing against the walls of the combustion chambers and then finding a way out where there is less pressure.

Another way to look at it: if you have a heavy rock and you are on sheer ice. If you throw the rock, you will be pushed in the opposite direction of where you threw the rock.
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Relevant Pages

  • Re: Heres one for Bob (hope it makes your head spin)
    ... Another way to look at it is to look at ion engines. ... and is then accelerated by magnets out of the engine. ... To accelerate the ship by an extra 1km/h, ...
    (comp.os.vms)
  • Re: Can electromagnets push?
    ... Yes --- Which is how and why an ion drive such as was succesfully ... recoil of the ion engine. ... suspended between the electrodes of the ion engine, ... influenced by the field and they accelerate. ...
    (sci.physics.accelerators)