How fast do I have to go?

Discussion in 'Fred's House of Pancakes' started by imntacrook, Dec 28, 2005.

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  1. imntacrook

    imntacrook New Member

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    I was driving the Prius around a 1 mile oval, my average speed for the first mile was 30 MPH. How fast do I have to go on the second lap, to average 60 MPH for the entire 2 miles?? And what is you reasoning?
     
    #1 imntacrook, Dec 28, 2005
  2. jeneric

    jeneric New Member

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    Okay, you found the nerds, quit making fun. Ha ha.
     
    #2 jeneric, Dec 28, 2005
  3. 2Hybrids

    2Hybrids New Member

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    considering I'm a mathematically challenged individiual, and also that this is not a trick question, I had to count using my fingers - but would assume my calculation of 90 mph would be the answer...

    reasoning?... 60 divided by 2 = 30 + x ...don't laugh everybody - it "appears" to have worked for me...

    or maybe I just made an nice person of myself...
     
    #3 2Hybrids, Dec 28, 2005
  4. tripp

    tripp Which it's a 'ybrid, ain't it?

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    imntacrook leaves a train station travelling west at 50 km/h. A butterfly flaps its wings in Bejing at a rate of 120 flaps/min. The price of Oolong is $25/lb there as well. When will imntacrook get to Invercargill? :p :p
     
    #4 tripp, Dec 28, 2005
  5. DocVijay

    DocVijay Active Member

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    What grade is the Oolong?
     
    #5 DocVijay, Dec 28, 2005
  6. jeneric

    jeneric New Member

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    I've worked on a very similar problem a few months ago, since my wife has been doing a little tutoring. As I recall, it is a bit tricky.
     
    #6 jeneric, Dec 28, 2005
  7. zapranoth

    zapranoth New Member

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    Oolong is the protagonist in the coin-op game Yie Ar Kung Fu, I thought...
     
    #7 zapranoth, Dec 28, 2005
  8. jrohland

    jrohland Guest

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    You can't do it.

    60 MPH over 2 miles will take 2 minutes.
    1 mile at 30 MPH takes 2 minutes.
    You have no time left.

    jrohland
     
    #8 jrohland, Dec 28, 2005
  9. jeneric

    jeneric New Member

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    Yeah, and if you do the first minute as opposed to mile at 30m/h, I guess it is as easy as 2Hybrids figured out.
     
    #9 jeneric, Dec 28, 2005
  10. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    I don't think time is an issue here. I've read the original post several times and can't find where he says, "in n minutes."

    I just used the same logic that if you completed the first lap averaging 50MPH, you would have to average 70MPH in order to average 60MPH overall.

    A quick spreadsheet gave me these results:
    1st lap . . . 2nd lap . . Average
    50 . . . . . . . 70 . . . . . . 60
    55 . . . . . . . 75 . . . . . . 60
    50 . . . . . . . 70 . . . . . . 60
    45 . . . . . . . 75 . . . . . . 60
    40 . . . . . . . 80 . . . . . . 60
    35 . . . . . . . 85 . . . . . . 60
    30 . . . . . . . 90 . . . . . . 60

    [Edit]
    So in the end I agree with 2hybrids

    And to continue the question:
    If you drive the first mile at 30 MPH how fast would you have to drive to average 60 MPG? :rolleyes:
     
    #10 TonyPSchaefer, Dec 28, 2005
  11. imntacrook

    imntacrook New Member

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    Good answer!! You are correct!
     
    #11 imntacrook, Dec 28, 2005
  12. ceric

    ceric New Member

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    Ha,
    I was too late. I like math questions, which beat programming that I do everyday.
    Not to be picky but the correct answer is "infinite mph" since you asked, "how fast".

    60 mph = 1 mpm (mile per minute)
    time needed = 2 minutes for 2 miles
    first lap took 2 minute already
    2/(2+t) = 1, t=0, speed = infinite :D
     
    #12 ceric, Dec 28, 2005
  13. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    I stand by my claim. There is no mention of time. How can the answer introduce a new variable?
     
    #13 TonyPSchaefer, Dec 28, 2005
  14. Jaguar88

    Jaguar88 Member

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    I believe if you went an infinite speed you would arive before you left. I forget the equation but I seem to remember that as you approach the speed of light you get time dialation. IF you exceed the speed of light then you go backward in time.
     
    #14 Jaguar88, Dec 28, 2005
  15. 2Hybrids

    2Hybrids New Member

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    and if your flux capacitor was fully operational....
     
    #15 2Hybrids, Dec 28, 2005
  16. jimgraffam

    jimgraffam New Member

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    No mention of time... but there is the restriction that there's only one additional lap in which to contribute to the average. The first lap chews up the total time required to average 60mph over 2 laps.

    On the other hand, if it were mpg vs. mph, I'd recommend a generous use of EV mode :D
     
    #16 jimgraffam, Dec 28, 2005
  17. QED

    QED New Member

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    His average speed for the first (1) mile was 30 mph. Therefore it took him 2 minutes to travel one mile.

    Not a new variable, just a computed one.
     
    #17 QED, Dec 28, 2005
  18. imntacrook

    imntacrook New Member

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    Wormholes don't count.
     
    #18 imntacrook, Dec 28, 2005
  19. 2Hybrids

    2Hybrids New Member

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    warp?
     
    #19 2Hybrids, Dec 28, 2005
  20. Jaguar88

    Jaguar88 Member

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    I thought not.
     
    #20 Jaguar88, Dec 28, 2005
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