Quote:
Originally Posted by 3dknight
When the astronauts go into space with a space shuttle. They go at very high speeds and I was wondering if they blackout when entering or exiting the atmoshpere or even before that. And how many g's is it at top velocity.
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Just as a point of clarification, the g's don't depend on the velocity, but rather on the acceleration. Just think of a car. When you hit the accelerator hard, or hit the brake hard, you will feel g's. But even if you're going at top speed, you won't be pushed into the seat, because you're not speeding up or slowing down. For the space shuttle, the top velocity is generally speaking the whole time they are floating (in almost zero g) in orbit. But the highest g's are either when they hit the atmosphere or when they are about to dump the solid rocket boosters (because they have burnt up a lot of fuel, and the whole thing is lighter, making acceleration higher).
And the reason they black out during ceremonies and not in the ship is that even though it may be 4 g's, they are lying down on their backs. The reason you black out during high g's is because the blood either leaves your head. So lying on your back makes it much harder to black out.