I saw a really stupid post on Facebook talking about “how rockets don’t work.” Flat earther conspiracy nonsense. I started reading on all the points the post made and the only one I didn’t understand is how at 22 x the speed of sound a rocket does not really go over 3g’s of force.
My assumption is that as the rocket travels further from the earth the gravity influence also influences g’s on an accelerating object?
Please help me with this one.
Thank you
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In this context ‘g’ (lowercase) refers to the acceleration due to gravity at the surface of the Earth: 9.81 m/s^2 . It’s a change in the velocity of an object over a period of time. We often talk about acceleration in terms of Earth’s gravity because it’s relatively constant everywhere on Earth and because you can think about the relationship between acceleration and weight more easily. Like if you’re on the surface of the Earth and you start accelerating upwards at one g you would feel as though you were twice as heavy (because you already get one g from gravity). In application it doesn’t necessarily have anything to do with the force of gravity acting on an object.
If a rocket is accelerating at 3g’s that’s equivalent to 29.43 m/s^2 . To relate acceleration, velocity, and time you can use the equation V = 1/2 at^2 where V is the final velocity at the end of whatever period of acceleration you’re interested in. Rearranging gives t = sqrt(2V/a), and solving with a=29.43 and V=7581m/s gives t=22.69 seconds of constant acceleration, which is not unreasonable for a rocket burn.
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