# Factors affecting a moving object in space

## Recommended Posts

Hello everyone,

If a spaceship was accelerated to the normal speed it takes to leave our atmosphere, was factors would cause the slowing of said craft? I already know a collision would obviously prevent further movement, but what else would slow it down?

If a zero gravity condition were to present itself, would the craft perpetually travel forever?

Thanks in advance for the input.

Michael

##### Share on other sites

The basic factor that effects such an object would be gravity.

Just leaving the atmosphere of the Earth would not be enough to escape the Earth's gravity. It would slow you down and pull you back unless you were also moving fast enough. Even if you are moving fast enough to escape, Earth's gravity will still be slowing you down, just not at a great enough rate to pull you back to Earth.

Once you escape the Earth,you are still under the effect of the Sun's gravity. Again, unless you are moving fast enough you will just go into orbit around the Sun. You see there is no place in the Universe where there is exactly zero gravity, so it will always affect your trajectory in some manner.

##### Share on other sites

If a spaceship was accelerated to the normal speed it takes to leave our atmosphere, was factors would cause the slowing of said craft?

If a spaceship was accelerated to the escape velocity of $\sqrt{\frac{2GM}{r}}$, it would still need to apply an acceleration equal to the gravitational acceleration, so that the total force is zero. This force would get weaker with distance, but it would need a force equal to that of gravitation.

##### Share on other sites

If a spaceship was accelerated to the escape velocity of $\sqrt{\frac{2GM}{r}}$, it would still need to apply an acceleration equal to the gravitational acceleration, so that the total force is zero. This force would get weaker with distance, but it would need a force equal to that of gravitation.

Surely not. The whole point of escape velocity is that it is the velocity at which your current velocity is enough to allow you to coast away (technically to infinity) without any further force/acceleration applied.

If you look at how it is calculated this becomes obvious - it is the velocity at which kinetic energy and gravitation potential energy sum to zero (remember GPE will be negative)

Here is a good intro http://hyperphysics.phy-astr.gsu.edu/hbase/vesc.html

##### Share on other sites

Janus, the effect of other planets' gravity is not always decelerating. It depends on their locations.

##### Share on other sites

Surely not. The whole point of escape velocity is that it is the velocity at which your current velocity is enough to allow you to coast away (technically to infinity) without any further force/acceleration applied.

If you look at how it is calculated this becomes obvious - it is the velocity at which kinetic energy and gravitation potential energy sum to zero (remember GPE will be negative)

Here is a good intro http://hyperphysics.phy-astr.gsu.edu/hbase/vesc.html

Oh yes, thanks for pointing that out.

Drag.

## Create an account

Register a new account