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Homework Help: Stuck on finding force

  1. Sep 30, 2007 #1
    1. The problem statement, all variables and given/known data

    An adult 68.0kg cheetah can accelerate from rest to 20.1 (45.0mph ) in 2.00 s.

    2. Relevant equations

    Vf=Vi + (a)t

    3. The attempt at a solution

    Assuming constant acceleration, find the net external force causing this acceleration

    i solved for the time using Vf=Vi + (a)t. i got acc=10.05

    when i tried plugging in the 10.05 for the acceleration and times the mass it gave me 684N. Its coming up wrong and I dont know where im messing up on
  2. jcsd
  3. Sep 30, 2007 #2


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    Staff Emeritus
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    Gold Member

    When I multiply 68 by 10.05 I get 683.4. I would guess its just a rounding error.
  4. Sep 30, 2007 #3
    Are you sure its 684. you are messing up with the calculations, i suppose.
  5. Sep 30, 2007 #4
    yea actually did it would let you know if you where close but it says nothing about a rounding error
  6. Sep 30, 2007 #5
    actually no the computer was wrong thanks for the help though it was a glitch in the computer it has 2.01m/s as 45mph so it takes the right answer to be 68.3N. Man that is why I really hate online hw. but thanks anyway
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