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Homework Help: Rotational motion of rotating disc

  1. Jul 1, 2008 #1
    You stand on the edge of a large rotating disc. It rotates at a constant speed. You walk towards the centre of the disc. What do you experience?

    radius is decreasing, therefore inertia and linear velocity are decreasing.
    but angular acceleration will increase.
    i dont know if i'm right
  2. jcsd
  3. Jul 1, 2008 #2
    You have to think about it in terms of rotation. Not linear. So if the radius decreases and the angular velocity is constant. Then what happens?
  4. Jul 1, 2008 #3
    does a=angular velocity squaredX radius matter?
    in tht case would the centripetal acceleration decrease?
  5. Jul 1, 2008 #4
    I believe that is correct.
  6. Jul 1, 2008 #5
    so one would not experience any force? i was told that you would experience a force pushing you off the disc
  7. Jul 1, 2008 #6
    If it has an acceleration it must have a force. Remeber Newton's second law? I believe your talking about the centrifugal force which you will feel no matter where you are on the disc the only thing is it's magnitude will be different.
  8. Jul 1, 2008 #7
    wait im confused... so if one is to walk towards the center and the radial acceleration is decreasing, wouldnt the force decrease too? so what would happen? im sorry im kinda confused
  9. Jul 1, 2008 #8
    The centripetal force would decrease since the acceleration decreases. What are you specifically confused about?
  10. Jul 1, 2008 #9
    the question asks what would you experience... i thought somehow the force pushes you off the disc but if the force is decreasing, then nothing happens?
  11. Jul 1, 2008 #10
    Your linear velocity will decrease as your centripetal acceleration decreases. If you still have difficulty understanding this maybe the textbook can explain it better with an example on pg198 with the carousel.
  12. Jul 1, 2008 #11
    thanks =) i think i get it
  13. Jul 1, 2008 #12
  14. Jul 1, 2008 #13


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    Homework Helper

    Hi zila24,

    Since you mentioned the forces, in terms of the forces, as you walk toward the center, there would be two fictitious forces acting on you (from your point of view). They would act in perpendicular directions to each other. Do you see what would they be?
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