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Homework Help: Find acceleration of a ball

  1. Mar 16, 2010 #1
    The question is attached.
    The correct answer is D

    I got it as C first using the equation s=ut+1/2 a t^2
    I took s as h, and t= (t2-t1)

    I put u=0, which I discovered isn't correct. I then tried putting u=at1 and got a complex equation and got stuck there.
     

    Attached Files:

  2. jcsd
  3. Mar 16, 2010 #2

    kuruman

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    You need to understand that the equation

    s = ut + (1/2)at2

    gives the position of the object at any time t. In other words, you give me the time and I will use the equation to find the position of the object. So

    1. At time t1 the object is at s1 = ut1 + (1/2)at12

    2. At time t2 the object is at s2 = ut2 + (1/2)at22

    What is u? How is h related to s1 and s2?
     
    Last edited: Mar 16, 2010
  4. Mar 17, 2010 #3
    I'm sorry, I still don't get it. How do you solve this question?
     
  5. Mar 17, 2010 #4

    kuruman

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    What part exactly of my previous posting don't you get?
     
  6. Mar 17, 2010 #5
    I finally found it. I used this equation

    s=h
    u=at1
    v=at2
    t=(t2-t1)

    [tex]\frac{s}{t}[/tex]=[tex]\frac{u+v}{2}[/tex]
     
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