why cant a flying object just leave the atmosphere at a slower speed? why does it need to achieve ‘escape velocity’? if a rocket goes straight up at 100kmph without stopping, it should escape the atmosphere eventually right?
In: Physics
You can escape the atmosphere at any speed. Escape velocity is the speed at which, under the resistance of gravity alone, you will move faster away from the object than the object can pull you in, due to gravity weakening with distance.
Just under escape velocity, you might go out very very far but eventually turn around and go back.
At or above escape velocity, the rate at which the object pulls you back in will drop to almost nothing while you are still moving away from it. You have escaped the body.
It is important that escape velocity does not account for atmospheric drag, and also changes depending on your distance from the object. Escape velocity from earth in low earth orbit is much higher than at the moon.
You don’t even need to reach earth escape velocity until you want to go to a different planet. But you need to reach moon escape velocity to leave the moon and go to earth
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