Escape velocity
By Garavegeta
@garavegeta (963)
Kochi, India
November 24, 2012 3:25am CST
Do we actually know,what escape velocity is.
A rocket,as we know starts from rest,and initial velocity is not 11.12 m/s.So at what point should the velocity be 11.18 m/s to escape from earth?
This looks more complicated due to that fact that the value of 'g' is decreasing with height.
Actually this is not to be viewed like this-An easier way to understand escape velocity is to consider a body free 'falling' from infinity.The maximum velocity attained by that body on reaching the ground would be 11.18 m/s,same as that of escape velocity.So if a body needs to escape earth and go to the destination which is at infinity,it should travel with a velocity of 11.18 m/s.Now we know 
But still don't know at what point the velocity be 11.12 in order to escape from earth.
Can you tell me?Thanks
This looks more complicated due to that fact that the value of 'g' is decreasing with height.
Actually this is not to be viewed like this-An easier way to understand escape velocity is to consider a body free 'falling' from infinity.The maximum velocity attained by that body on reaching the ground would be 11.18 m/s,same as that of escape velocity.So if a body needs to escape earth and go to the destination which is at infinity,it should travel with a velocity of 11.18 m/s.Now we know
But still don't know at what point the velocity be 11.12 in order to escape from earth.
Can you tell me?Thanks4 responses
@mydanods (6513)
• Nigeria
24 Nov 12
a body can leave the earth if it has enough kinetic energy to match its potential energy, but the escape velocity is the minimal velocity needed to achieve this. if a body is at the earth's surface at a certain velocity and that velocity is equal to or above the minimal escape velocity, it can escape from earth. note that pe and ke depend on mass of the body and so minimal escape velocity for various bodies do differ.
@Combiflame (182)
• India
24 Nov 12
Roughly saying Escape velocity is the velocity which is needed by an object to break away from the Gravity/Gravitational force of other objects, particularly, planets and satellites. I would also like to correct one of your facts the escape velocity needed to escape from the gravity of the earth is 11.2km/s and not m/s. As for your question's answer I would say there is not a "set" point for achieving escape velocity as soon as this escape velocity's is achieved you get free from the effects of gravity. You can read more about it on Wikipedia they have very detailed topic about it. Hope this helps.
@natliegleb (5175)
• India
24 Nov 12
yes its true and after reading about the falling speed ,i was so impressed by the time taken and its quite fast too
@subhojit10 (7375)
• India
24 Nov 12
Thanks a ton for sharing this discussion. yes u are right, the escape velocity of a rocket is very high so that with such a velocity it can escape from the gravitational force or pull of the earth. After this its speed remains constant in the universe. For a normal being it is impossible to achieve such a velocity and that is the reason why rockets are being made to achieve such a high speed and astronauts are present inside them.
What say?
