# why does rocket travel fast before it can go into orbit ?

• why does rocket travel fast before it can go into orbit ?

Answer #1 | 07/02 2014 23:52
To combat the Earth's gravity?
Positive: 100 %
Answer #2 | 08/02 2014 06:30
Because its velocity goes on decreasing as g acts on it g=GM/(R+h)^2
Answer #3 | 08/02 2014 10:21
Because unless it does, gravity will pull it back to Earth. To be in orbit, it has to be going fast enough round the orbit that though gravity is still pulling it down, it is going fast enough sideways that it keeps missing the Earth... and goes round it in a circle instead. But once it's in orbit, the engines can close down because it will just keep going by itself. If it's high enough to be above the atmosphere, there is no air or anything else to slow it down and it will just orbit forever.
Positive: 0 %
Answer #4 | 08/02 2014 01:11
to overcome earth's gravity
Positive: 0 %
Answer #5 | 08/02 2014 04:58
What goes up must come back down, unless you can throw it hard enough. Gravity is pulling everything down, therefore you need to overcome that in order to climb out of Earth's gravity well. This is called an escape velocity. If you can accelerate hard enough you can overcome gravity completely and reach orbit, but on Earth that's about 11.2km/s.
Answer #6 | 07/02 2014 23:55
the earth's gravity is still pulling on these rockets, even once they're in orbit. If they're not moving perpendicular to the pull of gravity, at a certain very high speed, they'll be pulled back to earth. If they are moving sideways at just the right speed, their course is still deflected by the earth's gravity, but they'll move sideways just far enough, so that their flight path, curved by the force of gravity, will take them around enough of the earth's curved surface so that their distance from the earth remains constant.
Answer #7 | 08/02 2014 01:12
Any object on the surface of the earth is pulled by its gravitational force. This is the reason why we can't leave the surface unless we move with a very high velocity. In these cases, a velocity called escape velocity comes into picture. The value of earth's escape velocity is 11.2km/s. Meaning, any object that has to leave the surface of the earth needs to have a velocity of 11.2km/s. Thus rockets have higher velocity in the beginning as they have to escape the earth's gravitational pull.