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Baseball and Velocity

  1. Oct 8, 2010 #1
    1. The problem statement, all variables and given/known data

    1. Consider a man throwing a baseball. Given the following, calculate the velocity of the ball as it leaves his hand:
    1. The distance from his shoulder socket (humeral head) to the ball is 70 cm.
    2. The distance from his humeral head to the points of insertion of the muscles moving his arm forward is 9 cm (this is a simplification, as the shoulder is a complex joint).
    3. The velocity of the muscle shortening is 2.6 m/sec..

    Show your calculations neatly in the space provided to receive credit for your answer.
    Express your answer in m /sec., and round your answer to the nearest tenth.

    2. Relevant equations

    Velocity = Distance / Time ????

    3. The attempt at a solution

    Here is my first attempt at this problem: 2.6 m/ sec = 260 cm/ sec.

    70 - 9 = 61 cm

    61 cm / 260 cm per second = 0.23 m /second?

    Can anybody help me on how I should start this question? I would like to know how to start so I can begin to wrap my brain at it. Thank you. P.S. I don't know really know anything about velocity other than what I wrote above. Thank you!
    Last edited: Oct 8, 2010
  2. jcsd
  3. Oct 8, 2010 #2
    Here is my first attempt at this problem: 2.6 m/ sec = 260 cm/ sec.

    70 - 9 = 61 cm

    61 cm / 260 cm per second = 0.23 m /second?
  4. Oct 8, 2010 #3


    User Avatar

    Staff: Mentor

    Is there a drawing that goes with this question? It sounds like a geometry-type question, but it's hard to visualize what they are describing.
  5. Oct 8, 2010 #4
    No. Unfortunately no. I cannot believe my professor is even asking me to solve this question. But I will post some up a little later to assist you with the Human anatomy part of this problem.
  6. Oct 9, 2010 #5
    Someone wrote me this:

    Make yourself a diagram of this, and assume that the "man" keeps his arm straight while throwing the ball. (If he bends his elbow, all bets are off.) You'll see that you have a couple of similar figures: one with the portion of the arm between the socket and the point of attachment to the muscle, the other from the socket to the ball. One side of the smaller one (the muscle) is shrinking at 2.6 m/s. Given that, figure out how fast the ball is moving. Remember how similar figures work (sophomore geometry).

    I'm still trying to digest it.
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