At what altitude do the affects of gravity cease? When does "weighlessness" occur?

Question

I would like to figure out how high one has to fly to achieve weightlessness. Is the object in flight then free to travel into space, or would it be pulled back to Earth? Is there a set of calculations for determining altitude and gravitational pull?

Answer 1

The law of universal gravitation states that every particle of matter in the universe attracts every other particle with a force directly proportional to the products of their masses and inversely proportional to the square of the distance between them. Consequently, the gravitational pull exerted by the earth upon all other bodies (including spacecraft) diminishes with distance from the earth. The gravitational field, however, extends to an infinite distance; gravity does not cease to act at any altitude. A spacecraft is said to be weightless when it is in orbit around the earth (or around any other celestial body) because the centrifugal effect (which acts away from the center) is then equal and opposite to the force of gravity. Under these conditions, objects in a spacecraft seem to float in space. In the same way, the moon does not fall toward the earth because of the centrifugal effect that balances the force of gravity.

How do you compute the escape velocity of a particle leaving Earth's gravitational field?
If you do the math right, this should work out:

escape velocity = square_root (2 * G * mass of Earth / radius of Earth)

G = 6.67 x 10-11
mass of Earth = 6 x 1024 kg
radius of Earth = 6.4 x 106 m

Answer 2

The effects of gravity hold the moon in orbit, which is about 240,000 miles from earth, well beyond orbit,
Weightlessness is actually not caused by a lack of gravitational pull, but from the subjects being in freefall.
The space station is in orbit at about 190 miles up, which is much closer than the moon.

The effects of weightlessness can be experienced on a rollercoaster, or to a lesser degree on an elevator going down.

Answer 3

The force of attraction between two objects is given by the following equation:

(Force of Attraction) = (Gravitational Constant) * (mass1*mass2)/(Distance^2)

There is no such thing as weightlessness. The mass of an object simply ceases to have any measurable gravitational pull on other objects after they are a certain distance away.

Although astronauts work in microgravity environments, in orbit around Earth, they are still quite deep inside the Sun's gravity well.

Answer 4

It is not only the altitude but the speed that determines weightlessness. You would need to calculate the gravity at height and also the effect of momentum being disrupted as he takes a circular path. I just didn't want to call it centrifugal force.

I don't know how to do the calculations though.

Answer 5

In free fall there doesnt seem to be any weight. The reason is that the moving mass has not been hindered by any other mass. A weight only exists when there is two masses touching and pushing each other in opposite direction.
The same scenario applies to any mass structure in space. The Earth itself is weighless in space and distorts the substance of space as it moves in the Universe.That is why Einstein named Gravity force as fictitious .That means
There is no weight in space only mass structures.

Answer 6

If you mean why are the astronauts weightless in orbit, it has nothing to do with height. The only reason the satellite is there is that its orbital motion counters the effect of gravity. If it suddenly was halted, the astronauts would have weight again and the thing would plummet.

Answer 7

Yes, lots of calculations.

For the earth, "escape velocity" is about 60,000 MPH.

The shuttle and space station are still effected by gravity, they just "fall" around the earth moving "forward" at just the right speed so they curve in a circular orbit.

Answer 8

I'm not sure but I think NASA planes fly thousands of feet and then fly up and down to simulate 0 gravity.