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Wired question request some pro help

  1. Sep 29, 2008 #1
    I have a question that is not present in any physics book I've ever seen:
    Supose I have a rocket with infinite fuel, but it's mass is constant. This rocket's power is limited and can only provide enugh thrust to accelerate it self at a rate of just over 9.81M/s. If I were to lunch this rocket straight up into the air with a equipment onboard(with zero mass) that will absolutly keep the rocket from changing direction.(reletive to earth's rotation axis)
    The question is, is this rocket able to get into space (higher than the lowest stable earth orbit).
    The second question is, without increasing it's power, is it possible to enter an earth orbit after it's in space.
    this question is driving me crazy trying to convince people that the escape velocity and so on don't apply to this situation..... They just keep saying I make no sense and nothing can go into space without a minimum orbit velocity.
    I know I'm right that this thing can go into space but looks like most people don't even understand what do the words in those physics textbooks mean. too bad I'm not good at school physics and can't explane with super pro-looking equations.....
  2. jcsd
  3. Sep 29, 2008 #2


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    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi jacobgong! Welcome to PF! :smile:

    You're right, of course, that it can go into space …

    if you rise at a constant speed of one metre per second for a million seconds, you'll obviously go a million metres (1000 Km) …

    keep going long enough, and you can go as far as you want! :smile:

    But getting into circular orbit will be more difficult … I suppose you could use the extra acceleration (you'll need less and less as you go higher, so there'll be some over :wink:) to go sideways a little, and gradually build up the sideways velocity until you reach orbital velocity.
    btw, H. G. Wells had the identical idea …
    in The First Men in the Moon, a Professor Cavor invented cavorite, an gravity-blocking device which took him to the moon at roughly that speed. :biggrin:
  4. Sep 29, 2008 #3
    Thanks, I thought so....
    But the problem remains, without a super mind-blowing and eye catching list of equations, my reputations remains as knowing nothing about physics and ignores the laws of gravity, escape velocity and so on and so forth..... So, how can I convince people that I'm right about it? cause they're taking what I said as a joke and posting them on forums to make fun of me.....
    I just wanna prove to them that I've been right and they didn't understand what Newton's laws ment. and don't worry it's not cyber bullying.....:smile:
  5. Sep 29, 2008 #4


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    Staff: Mentor

    What "they" appear to be missing is that escape velocity is the velocity you need to escape without propulsion.
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