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What's the answer?

  • 04-08-2013 05:42PM
    #1
    Registered Users, Registered Users 2 Posts: 40


    A car travels 2 miles.

    It does the 1st mile at exactly 30mph.

    What speed does it travel at to get an average speed of 60mph over the 2 miles?


Comments

  • Registered Users, Registered Users 2 Posts: 2,201 ✭✭✭jamesbondings


    90mph??


  • Registered Users, Registered Users 2 Posts: 40 forumlover


    Wrong


  • Registered Users, Registered Users 2 Posts: 2,201 ✭✭✭jamesbondings


    no idea, pm me the answer will ya??


  • Moderators, Category Moderators, Social & Fun Moderators, Society & Culture Moderators Posts: 24,519 CMod ✭✭✭✭Ten of Swords


    By travelling the first mile at 30mph it is impossible to achieve average speed of 60mph over 2 miles. It cannot be done.

    T=time, D=distance, S=speed (T=D/S)

    Time required for average speed over 2 miles @60mph: (D=2,S=60) therefore T=2/60 -> 1/30 of 1 hour... 2 minutes

    Time taken travelling the first mile @30mph : (D=1,S=30) therefore T=1/30 of 1 hour as above... 2 minutes

    There is simply 0 time left in order to achieve an average speed of 60mph, even travelling at the speed of light would not be fast enough.


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