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Homework Help: Stones and velocity

  1. Jun 3, 2005 #1
    Question: A stone is thrown verticall upward with a speed of 18.0 m/s. (a) How fast is it moving when it reaches a height of 11.0m? (b) How long is required to reach this height?

    a. Work

    v(i)=18.0 m/s
    x=11.0 m
    x(i)=0
    g=9.8 m/s ^2
    v=?

    v^2=v(i)^2-2g(x-x(i))
    v^2=18^2-2(9.8)(11-0)
    v^2=324-215.6
    Answer: v=10.41 m/s

    b. Work

    v=10.41 m/s
    V(i)=18
    g= 9.8 m/s^2

    v=v(i)-gt
    10.41=18-9.8t
    -7.56=-9.8t
    Answer: t=.77 seconds

    Did I do these problems correctly?

    Thank You :smile:
     
  2. jcsd
  3. Jun 3, 2005 #2

    dextercioby

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    Science Advisor
    Homework Helper

    Looks okay to me...

    Daniel.
     
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