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Shopping cart problem help

  1. Sep 11, 2009 #1
    1. The problem statement, all variables and given/known data
    Jill has just gotten out of her car in the grocery store parking lot. The parking lot is on a hill and is tilted 3 degrees. Fifty meters downhill from Jill, a little old lady lets go of a fully loaded shopping cart. The cart, with frictionless wheels, starts to roll straight downhill. Jill immediately starts to sprint after the cart with her top acceleration of 2.0m/s^2.

    2. Relevant equations



    3. The attempt at a solution
    a(cart)=g*sin3=.51m/s^2

    I know I need to use two equations to find the solution, but I am utterly confused on which two to use.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Sep 11, 2009 #2

    tiny-tim

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    Welcome to PF!

    Hi Mirole! Welcome to PF! :smile:
    Use the usual https://www.physicsforums.com/library.php?do=view_item&itemid=204" equations, but use s in one and s + 50 in the other. :wink:
     
    Last edited by a moderator: Apr 24, 2017
  4. Sep 14, 2009 #3
    Re: Welcome to PF!

    Alright, thinking about it.

    I went:

    S(1) = 1/2*a(j)*t^2
    S(2) = 50 + 1/2*a(cart)*t^2

    I set them equal to each other.

    1/2*a(j)*t^2 = 50 + 1/2*a(cart)*t^2

    1/2*2*t^2 = 50 + 1/2*.51*t^2
    Cross off the t^2s.

    1=50+1/2*.51
    1=50.255

    That's obviously not right, and this problem has given me a mental block. :(
     
    Last edited by a moderator: Apr 24, 2017
  5. Sep 14, 2009 #4

    tiny-tim

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    Hi Mirole! :smile:

    (try using the X2 tag just above the Reply box :wink:)
    "Cross off the t^2s" ??

    get some sleep! :zzz:​
     
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