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Help with Newtons Second Law Question Please.

  1. May 19, 2009 #1
    1. The problem statement, all variables and given/known data

    Calculate the force needed to accelerate a 2.0kg ball at 3.0ms^2

    (A) In space, a long way from Earth.
    (B) On a frictionless horizontal surface, near the surface of the earth.
    (C) vertically upward, near the surface of the earth.


    2. Relevant equations

    F = m*a

    3. The attempt at a solution

    (A) F = 2.0 * 3.0
    F= 6N?

    (B) Same as above?

    (C) I am confused on this one.

    Would it be F = m*a

    F = 2.0 *(9.8 - 3.0)
    F= 2.0 * 6.8
    F= 13.6N?

    or

    F = 2.0 * 12.8 (To get from -9.8 to 3 = 12.8)
    F= 24.8N

    If those answers are wrong could anyone point me in the right direction as to what I am doing wrong?

    Thanks.
     
    Last edited: May 19, 2009
  2. jcsd
  3. May 19, 2009 #2
    Edit: Aha, check your final line, you sure That 2 * 12.8 = 24.8? 0.o

    First two are fine
     
  4. May 19, 2009 #3
    Ahaha... I mean 25.6 :)
     
  5. May 19, 2009 #4
    thats right
     
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