Sunday, October 9, 2011

Rotation and Applications

So here I have a video for all of you.



I have a few questions... Hopefully Professor Ellis has not addressed this example in class.

What does the figure skater do to achieve three rotations?
Other than stability, why does she throw her hands out at the end of the rotation?

11 comments:

  1. Hey Brandon,

    I guess I will take a stab at this question. It seems the skater was able to achieve the three rotations by wrapping her arms around herself to increase the speed (angular velocity). She throws out her hands afterwards to slow herself down.

    Reynold

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  2. Hey! I realize that this was posted a week and a half ago, but yes, Dr. Ellis has addressed this. I agree with Reynold; after building moment by skating around, the skater was able to achieve three rotations by pulling her arms in tighter to her body, and as she stretched them out again, she slowed down.

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  3. She is able to accomplish her three rotations by angling her body and spreading her arms which increases her angular velocity. And as the two above me said, she spread her arms out, after the landing, to slow herself down.

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  4. As everyone has said before me, the skater was able to achieve three rotations because she increased her angular velocity by bringing her arms in while in rotation and then slowed down by extending her arms out to land. Obviously the distribrution of mass has a lot to do with it but I was also considering if the amount of kinetic friction had anything to do with it. If you try to run and do a triple axel on concrete, you can not complete the task. at most you could do two rotations. So based on that i assuming the type of friction and the amount affects this ability as well.

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  5. by bringing her arms in while rotating!

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  6. I have always enjoyed watching figure skaters and I was always impressed by the speed that the skaters obtained with the were spinning. Until prof ellis's demonstration in class, I did not realize that gaining speed was caused by bringing arms in close the the body.

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  7. When the skater brings her arms inward she achieves increase in her speed.Also when spreading out the arms causes the speed to decrease.This was just like Dr. Ellis example when she was on the chair demonstrating angular velocity to the class.

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  8. Yes, by bringing her arms in.

    Jessica Lang

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  9. The angle of her body, or angular momentum, when she kicks off the ice, in addition to the kick and bringing in of her leg and arms. This decreases drag and centers the mass of the ice skate- all about centripital force. By opening her arms after the trick, she once again slowed down as she increased drag.
    -Hannah Roddy

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  10. Did you guys know conservation of angular momentum is found in massive stars when they die? The rotating star begins to collapse and decreases its moment of inertia. The angular momentum is conserved, and the and the rotational period increases. Cool!
    -Hannah Roddy

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  11. Just like in class when Dr. Ellis showed us that she would spin faster with her arms in and then slowed down when she put her arms out.
    -Matt Outlaw

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