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Homework Help: Impulse help

  1. Mar 7, 2005 #1
    Impulse help!!

    A 0.09 kg tennis ball with a speed of 43.2 m/s strikes the ground at a 45.4 degree angle and rebounds with the same speed and the same angle (see the figure below). What is the magnitude of the impulse given to the ball by the ground?

    Does anyone have any clue?? I sure don't.
  2. jcsd
  3. Mar 7, 2005 #2
    Impulse = change in momentum / time.

    Guess you can start by finding dP
  4. Mar 7, 2005 #3


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    This isn't just some random problem designed to make you do some math. Ask yourself, "what key concept about physics that I am supposed to learn about is being tested here?" Do you know the definition of impulse? (If you don't, then learning it would be a good place to start, considering that's what you're being asked to calculate!) Furthermore, have you heard of the impulse-momentum theorem?
    Last edited: Mar 7, 2005
  5. Mar 7, 2005 #4
    I don't know what to do with the angles...
  6. Mar 7, 2005 #5


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    Use the geometry and the property of vectors to be decomposed after orthonormal coordinates.In your case,one component from the initial vector will not transfer momentum at all,while the other will transfer it all.

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