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Homework Help: How can I determine Velocity?

  1. Oct 13, 2007 #1
    What is the velocity of a 178 gram object (softball, 11inch diameter) thrown 97 meters. Can anyone help?
  2. jcsd
  3. Oct 14, 2007 #2
    Velocity is vector (magnitude [speed] and direction). I assume you want the speed.
    To find speed you need to know the distance traveled over time (least for average speed). Unless you are figuring out force, you don't need mass. So give me a time and I'll give you an average horizontal speed. If you truly want to find VeLoCiTy you need to know a lot more like change in y displacement and an angle and how you threw the ball.
  4. Oct 14, 2007 #3
    i think its much easier than tht..but my question is which velocity do you want to find: the initial or the final velocity?
  5. Oct 14, 2007 #4
    i am guessing it is the final velocity. so the initial velocity will be zero since the object is thrown. The acceleration is 9.8m/sq. sec. And we know the distance. So using the formula V^2- u^2=2as. hence we can find the final velocity. Its best you check with some expert.
  6. Oct 14, 2007 #5
    I don't think we can determine the actual velocity based on the information given. I believe you can only have an initial vertical velocity is zero if: the ball is thrown horizontally, or the ball is dropped from somewhere, or you are told it is zero. So, if we assume the ball is thrown horizontally, we still cannot determine the final vertical velocity as we do not know either how far vertically it moved, or for how long it was in the air.

    As to horizontal velocity, there doesn't seem to be enough information to get an actual velocity. With all the unknowns, I think we can make a formula, but not determine the value.

    Perhaps one of the experts has the key.
  7. Oct 14, 2007 #6


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    Staff Emeritus
    Science Advisor

    Need more information.

    If on earth, the local acceleration of gravity, g = 9.8 m/s2.

    Is ball thrown vertically or horizontally or at some angle with respect to horizontal?
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