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Homework Help: Constant force of ball

  1. Jan 3, 2008 #1
    1. The problem statement, all variables and given/known data
    A 5.00 kg ball strikes a wall with a velocity of 6.0 m/s to the left. The ball bounces off with a velocity of 5.0 m/s to the right. If the ball is in contact with the wall for 0.30 s, what is the constant force exerted on the ball by the wall?

    2. Relevant equations


    3. The attempt at a solution

    Ok so i found p which i did mv or (5)(11) then plugged it to p/t and did 55/0.30 and got 183.3 N to the right...is that correct?

  2. jcsd
  3. Jan 3, 2008 #2


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    Initial momentum is 5*-6=-30 kgms^-1

    Final momentum is 5*+5=+25kgms^-1

    what is the change in momentum? how does newton's 2nd law apply?
  4. Jan 3, 2008 #3
    oh....so 5 **Net force on an object is equal to its rate change of momentum.
  5. Jan 3, 2008 #4
    but that's such a small number is that possible??
  6. Jan 3, 2008 #5


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    The change in momentum=Final-Initial=25-(-30)=55kgms^-1

    and by newton's 2nd law:F=55/0.3

    so you are correct.
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