# Escape velocity question.

• blackcat
In summary, the space shuttle needs to achieve escape velocity in order to travel to other planets or moons. This is because the potential energy at an "infinite distance" is zero, and it becomes useful when you get into the math.f

#### blackcat

i know escape velocity is the velocity you need to give an object for it exit the pull of the Earth and travel an infinite distance away from earth.

now let's say you have a space shuttle that you need to take to Mars or the moon or something. why would you need to give it the escape velocity when you're only going a few million kilometres and not anywhere near an "infinite distance" away?

so how does that make sense?

ow let's say you have a space shuttle that you need to take to Mars or the moon or something. why would you need to give it the escape velocity when you're only going a few million kilometres and not anywhere near an "infinite distance" away?
It doesn't matter where/how far you are going. You just need that velocity to escape the gravitational attraction so it won't fall back down. From there is up to the space shuttle where to go.

Dont use "infinite distance away from earth", you'll confuse yourself. For simplicity sake, it should be finite distance.

thanks, but i still don't quite understand.

what will happen if you launch with escape velocity (and without propulsion). in wikipedia it says you'll get infinitely far away, but you say it doesn't matter.