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Homework Help: Need Help With Calculating Forces (Circular Motion)

  1. Oct 12, 2012 #1
    While a person is walking, his arms (with typical lengths 70 cm measured from the shoulder joint) swing through approximately a 45 degree angle in 0.5 s. As a reasonable approximation, we can assume that the arm moves with constant speed during each swing.
    Find the magnitude of the force that the blood vessel must exert on the drop of blood.

    (I've already calculated the acceleration of 1.00 g drop of blood to be 1.7m/s^2.)

    I've tried using n-w = m(v^2/r). Its not going so well. Is this the correct equation? Can you get me started? Thank you.
  2. jcsd
  3. Oct 12, 2012 #2
    could you explain what you mean by drop of blood?
  4. Oct 12, 2012 #3
    That's all that the problem gives. I assume it just means one drop of blood that is in the arm.

    Also I need to find: What force would the blood vessel exert if the arm were not swinging?
  5. Feb 9, 2013 #4
    How is that even possible? I mean in that case, the arm would move in a cycle! That's not how a man/woman usually walk... It's more like a harmonic motion, getting max when the angle is 0° and minimum when it's 90°! Did you think about that?

    :P Sorry for the late reply!
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