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Homework Help: Force and Momentum problems

  1. Mar 15, 2015 #1
    1. The problem statement, all variables and given/known data
    A catcher stops a .250kg ball traveling at 100km/hr in .19s.
    a. Calculate the change in momentum of the baseball [-6.9ns]
    b. Calculate the force the catcher applies to the baseball [-36.5n]

    2. Relevant equations

    3. The attempt at a solution
    a. △p=m△v

    b. F△t=m△v

    Both answers are wrong. Correct me please.
  2. jcsd
  3. Mar 15, 2015 #2


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    Gold Member

    In your attempt you have 100m/s but in your question, you have 100km/hr, you see the difference? Looks like you need to do a conversion.
  4. Mar 15, 2015 #3


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    Science Advisor

    You need to pay more attention to the units. Getting the units right in these problems is usually the most difficult part. 100 km/hr is not the same as 100 m/s.
  5. Mar 15, 2015 #4
    Yes! Thank you so much. I will be careful with the units.
    And attempt to solution B, I was using an Impulse formula and I made a mistake.
    When you try to solve for the Force. You must divide time from the force.
    So It would be,
    F=36.55 N
  6. Mar 15, 2015 #5


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    Science Advisor

    I think this is now correct.
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