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About a bee flying inside a moving train

  1. Mar 25, 2007 #1
    I have some questions which i cant seem to answer and understand. Here goes:
    Imagine a bee flying inside a moving train moving at a constant velocity in one particular direction. the bee is flying in mid-air and is not in contact with any of the train parts.

    qns 1: does the bee need to continously flap its wings(so to speak) to fly forward in other to maintain in the same position?

    qns 2: is there any difference when the frame of references are one inside the train and one outside the train.

    qns 3: what will happen if the train accelerates? i feel that in this case, the bee will have to exhaust energy to fly forward in order to maintain in the same position but i am not sure and doesnt know to explain it.

    thanks a million for helping me out with this question.
  2. jcsd
  3. Mar 25, 2007 #2
    No the bee doesnt need to flap its wings to fly forward to maintain the same position.

    Yes ofcourse there is....the person viewing from outside thinks that the bee is moving.....whereas the person inside the train thinks the bee is stationary
  4. Mar 25, 2007 #3
    everything inside the train is going the same speed as the train, even the bee.. You don't feel the air from inside the train blowing in your face in the train, it is also moving.. In the same way the bee is also moving even though it hasn't contact with any solid materials...

    so like anantchowdhary said: the bee doesnt need to flap its wings to fly forward to maintain the same position.
  5. Mar 25, 2007 #4
    I think the second question is asking if there is a difference not in the point of view but in the force needed to keep the bee moving when you see it from outside the train. Seen from inside the train, the bee is stationary. Seen from the outside, it has a uniform linear motion. In neither case do you need to apply a force to keep it that way.
  6. Mar 25, 2007 #5
    Oh, and for question 3, if the speed of the train ceases to match the speed of the bee then the bee will appear to be accelerating in the opposite direction when seen from the inside. It can counter this apparent acceleration by applying a force (using its wings). Seen from the outside, the bee will need to accelerate to match the train speed by applying that same force.
  7. Mar 25, 2007 #6
    just so long as we all agree that the bee better be flapping something to stay aloft! :wink:
  8. Mar 25, 2007 #7


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    Anantchowdhary and Maxwellsdemon don't seem to think that! Perhaps they could explain what is going to keep the bee aloft.
  9. Mar 25, 2007 #8
    hehe.....i think the question was as follows:
    qns 1: does the bee need to continously flap its wings(so to speak) to fly forward in other to maintain in the same position?

    .....so i really think its about linear motion...Therefore i gave my answer
  10. Mar 25, 2007 #9
    I agree with all of you. I guess I was just bad at telling you in the right way :)
  11. Mar 25, 2007 #10
    Could u pls elaborate??are we correct or not??
  12. Mar 25, 2007 #11
    I was just trying to add a little "levity" If it were an ant, non-flying variety, no problem.

    If you'll forgive an aside, reminds me of the balloon in a car collision problem that came up recently--suppose a helium balloon is tied to the gearshift of your souped up sport input which due to your inattention, hits a brick wall at 60MPH, in which direction does the balloon first travel?
    Last edited: Mar 25, 2007
  13. Mar 25, 2007 #12
    we are correct
  14. Mar 25, 2007 #13


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    'About a Bee' - isn't that a Hugh Grant Movie?
  15. Mar 25, 2007 #14
    Opposite to the pendulum that was suspended above it. Actually, both would continue in the original direction of the car except that, being tied to a string, the balloon would also accelerate downward and the pendulum would accelerate upward. Did I get it?
  16. Mar 25, 2007 #15


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    The key to understanding this question is to recognize that the bee interacts directly with (and thus all its motion is referenced to ) the volume of air in the train - and deos not intreract with the train itself or the outsdie world. Ask first what effect the train's movement has on the air. Once you know that, ignore the train and ask what the bee does wrt the air it is flying through.
  17. Mar 25, 2007 #16


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    No. The key to understanding balloon behaviour is to understand the behaviour of the air around it.

    The sum total of the mass - and thus interia - in the ballon and all its helium is LESS than the sum total of the same volume of air that the balloon is displacing. So the air in the car continues forward with greater enthusiasm (read: inertia) than the helium balloon. Thus, balloon strains backward upon impact.

    Another way to understand it is to think of a helium ballonn as - not an object - but as a small bubble of low vacuum in the air. It's the air that acts, not the bubble of vacuum.
    Last edited: Mar 25, 2007
  18. Mar 25, 2007 #17
    Ah, got me. Nice one!
  19. Mar 26, 2007 #18
    Suppose we perform the experiment in vacuum....if there was some way to keep the bee aloft...Would the bee then also stay in the same position even if the train moves??
  20. Mar 26, 2007 #19
    Nope. no reason i can think of.
  21. Mar 26, 2007 #20
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