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Homework Help: Unifom accelaration question about racing

  1. Oct 1, 2011 #1
    1. The problem statement, all variables and given/known data
    Two go-carts, A and B, race each other around a 1.0km track. Go cart A travels at a constant speed at 20.0m/s . Go cart B accelerates uniformly from rest at a rate of 0.333m/s2. Which go-cart wins the race ? and by how much ?

    EDIT: When it says around it means they raced one lap around the track going at a constant speed, except for Cart B, its going at a constant acceleration

    Don't go too deep into the shape of the track, it doesn't really matter, however if you still do, its going in a straight path.

    2. Relevant equations
    I don't know which to use.


    3. The attempt at a solution

    Well I know that Go-Cart A take 50 seconds to cross the line.

    20m/s / 1000m = 50 seconds
     
    Last edited: Oct 1, 2011
  2. jcsd
  3. Oct 1, 2011 #2
    Do you mean to say that the track is not circular? After all, you said that
    , by "around", did you mean perhaps that the segment is round?
    If not, recall that kinematics equations:
    [itex]
    \large
    x = \frac{at^2}{2}
    [/itex]
    Where a is your constant acceleration; But do clarify your stance on the shape of field etc...
    Daniel
     
  4. Oct 1, 2011 #3
    Fixed
     
  5. Oct 1, 2011 #4
    Okay, thank's for allaying the mix-up.
    What's stopping you from using the equation above? Find the time it took each to cross said distance, which will indicate firstly, who won... Then, measure how deficient/far was the loser by that moment in time.
    Daniel
     
  6. Oct 1, 2011 #5
    Don't know what equation to use ...

    so lost.. physics teacher was away for a week and the whole class is lost
     
  7. Oct 1, 2011 #6
    Okay, okay, not to worry, there's no need to panic.
    You have, from my post:
    So plug in your data here for each car.
    In one, x is simply v*t(the one with the constant velocity).
    in the other, the above mentioned formula.
    Find T for each(a is the constant acceleration).
    Compare the results; Whosever t is greater, lost the race(took him longer to cross the track).
    Then, find where was the loser at the time T of the victor.
    It's as simple as that,
    But it would help greatly if you could point-out where you're having difficulties,
    Daniel
     
  8. Oct 1, 2011 #7
    Thanks a lot Daniel, you're a life saver

    MAY GOD BLESS YOUR WARM KIND HEART !! <33333333333333333
     
  9. Oct 1, 2011 #8
    So I reckon you solved it properly, well done! :)
    Good job,
    And keep up the good work,
    Daniel
     
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