HD Felix Baumgartners space jump

[suityou01]

Orbits are just altitudes @ such a speed that although you're constantly in free fall towards the centre of gravity, you're also moving forwards around that center of gravity at the right speed so that you constantly are falling around it - rather than flying off into space, of falling to the ground.

Just imagine throwing a tennis ball - it free falls to the ground, but takes an arc passage through space. If you judge it right you could get a perfect quarter circle path.

Not imagine that the ground beneath your feet was a single point centre of gravity - when that tennis ball completes it's first quarter circle it is not moving straight 'down' (as we'd imagine it), yet the gravity is pulling it sideways back to you. So now it's in exactly the same state as it was when you first threw it, except starting a quarter of a circle round already - now it'll happily do another quarter circle, and so on.

That's why shuttle missions, etc, take off and fly east - we're already hurtling eastward at high speed, so if they tried to fly west they'd have to use a lot more energy to get to such a speed that they can find an orbit.

So it's nothing to do with simple mechanics and force equilibrium then

[SpontaneousOrder]

Geostationary orbit is a different thing again. This is where the satellite is much further out - 22,236 miles to be precise, where due to the distance out the strength of earth's gravity is much less. ....

No, this is wrong. It has nothing to do with weaker gravity.
It's simply that that is the required altitude where it is possible to maintain an orbit while going the required speed to remain over the same geographic location - higher orbits need slower speeds than lower ones.

If the altitude were lower then the speed would have to be faster, and the it wouldn't be geostationary. If the altitude were higher then the speed would have to be slower, and again it wouldn't then be geostationary.

**edit** sorry - you was mostly right. Just that the gravity differential is not particularly relevant.

[SpontaneousOrder]

The resolution of the forces between the anglular rotation of the orbit, and the direct pull of the earth cancel out. If the force of the angular rotation was greater or less than that of the gravitational pull, ie not in perfect balance then sustained orbit would not be possible and one of the forces would win, ie the module would fall to earth, or spiral off into space.

It is a force equilibrium that generates weighlessness.

What he said.

[EternalOptimist]

there is something fundamentally wrong with the universe when it allows things like this to happen


nice jump though felix

[suityou01]

What he said.

I'm done with adding folks to my sig as they already know I'm brill

Thanks btw.

[KentPhilip]

there is something fundamentally wrong with the universe when it allows things like this to happen


nice jump though felix

Nonsense!
Without all this stuff we would have no Sky TV!

[suityou01]

there is something fundamentally wrong with the universe when it allows things like this to happen


nice jump though felix

You mean the jump, or me being right?

[KentPhilip]

One interesting thing (I think) is that if you could have trains capable of travelling at 18,000 mph, or even planes capable of the same, you would not need tracks or wings, because the craft would be weightless for the journey, even at the surface of the earth.

[SpontaneousOrder]

there is something fundamentally wrong with the universe when it allows things like this to happen


nice jump though felix

When you imagine the aussies walking around upside down, and the chinese walking around sideways, and the yanks waling around sideways on the other side, then it would seem weird if it worked any other way!

[EternalOptimist]

You mean the jump, or me being right?

Felix jumped unassisted. Believe me, if it had been you, you would have had a shove