If I threw a ball in the air, at what speed would the ball come down if I threw it 25,000,000,000 feet in the air?

Question

jamesj · Answer

So you want to know how fast the ball comes down if

- the ball doesn't burn up in the atmosphere on its trajectory away from the earth

- it successfully reaches this astronomical height; very literally astronomical, being 7.6 million km away, ~20 times the orbit of the moon

- the ball doesn't burn up on its re-entry

- we also ignore air resistance so the ball hasn't reached its terminal velocity (because if we had to consider air resistance, it would have lost so much KE on its way out as to never reach 7.6 million km)

Is that what you're asking?

stormfire1 · Answer

@JamesJ: Good points.  The question to me can simply be answered by saying 0 m/s.  It won't be coming back down ;)

jamesj · Answer

Indeed :-)

anonymous · Answer

it will become a satellite

jamesj · Answer

I think that is highly unlikely without some sort of mechanism to calibrate the angular velocity of the ball consistent with a satellite orbit.

Anyway, if any of you are planning on launching a ball 25 billion feet off the earth, let us (and NASA) know.

anonymous · Answer

with o much height and corresponding velocity,i was thinking of attaining escape velocity and becoming a geostationary orbit

anonymous · Answer

Apply the principal of conservation of energy :
                                                                   total mechanical energy at initial =total mechanical energy at final=>0+mgh=1/2mv^2+0
                                       =>v=squareroot(2gh).......and get your answer apply this equation.here we assume that there is no air friction on the ball.

jamesj · Answer

@taufique, no that is wrong.  That formula is only correct if you are in a constant gravitational field of acceleration g.  That is clearly not the situation here.

@soham, I know what you're saying.  The challenge is turning the velocity into mostly  velocity in the tangential direction vs. radial direction so that the gravitational force provides the necessary centripetal acceleration to sustain an orbit.  

While a ball thrown up from the earth at any points other than the poles do have some tangential velocity (this is why we try to launch space craft as close to the equator as possible), it seems very improbable that this ball will have exactly the right mix of directions of velocity anywhere in its trajectory in order to achieve orbit.

anonymous · Answer

thanks..i understand