Originally posted by Unkown Target
Ahem, ahem....
G-Force is the amount of pressure gravity pushes down on a body with.
In fact, the "G," in G-Force stands for "gravity".
The most common example: a high-preformance jet.
When you pull back on the stick in the jet, you go up, and, since gravity is pulling you downwards at exactly 1 G, your going up in a hard turn presses you down harder, and, therefore, you can get up to the eyeball-popping force ofm about 10 Gs.
Now, without gravity, you would simple stay weightless, don't believe what the ****ty Wing Commander movie tells you 
Nope. Not true. G-force is the action on a body caused by conservation of momentum.
When you corner in a car quickly you feel a pull sideways opposite to the direction you are steering in. If G-force was
caused by the Earth's gravity why would it pull you sideways?
What is going on is this. You`re travelling down the road at 70mph. The car is too. When the car suddenly changes direction your body tries to continue in a straight line. Therefore you feel a force pulling you in the direction you were travelling. That's G-force.
Astronauts experience huge G-Forces not because the Earths gravity is pulling on them hard but because they were sitting still when suddenly the rocket around them is trying to accelerate at high speed. The rocket has to push on the pilot hard to keep him sitting in the seat (instead of sinking through it!).
Gravity is a function of mass and the distance from that mass. In the case of a rocket launch the mass of the Earth is staying the same and the rocket is moving AWAY from the centre of mass. So why would the pull of gravity increase?
The confusing thing is that G-force is measured in gravities. Don`t let that confuse you. The force isn`t caused by gravity it's just that saying that you`ve pulled a barrel roll in your fighter jet and experienced the force of 10 Earth Gravities is much easier (and cooler for that matter) than saying you experienced an acceleration of 98 metres per second per second (BTW that wasn`t a typo acceleration is measured in m/s/s).
In space G-forces act in exactly the same way. Although you might be weightless when the ship is sitting still if it starts moving you will feel G-force pulling you in the opposite direction to the one you`re travelling in.
