1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Not sure what subject this comes under, and not HW, just a problem.

  1. Jun 25, 2009 #1
    1. The problem statement, all variables and given/known data
    A plane travelling a distance of 660km, with unknown speed, has a tail wind of 60km/h, and due to this tail wind arrives at its destination 6 mins early.

    What is the speed of the plane without the wind?


    2. Relevant equations
    I have so far used s=d/t,

    3. The attempt at a solution
    Using s=d/t, i have got expressions for both s and t.

    s = (x + 16.7) m/s
    t = (x' +360) s and i have converted 660 km into metres, 660000m to get

    x + 16.7 = 660000/(x' + 360)

    However i am not sure if this is the right way of looking at it, so any help will be greatly appriechiated.

    Thanks
    John
     
  2. jcsd
  3. Jun 25, 2009 #2

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    Where is the "16.7" from?

    Why convert to meters?
    Let v be the speed, in km/h, without the wind, t the time, in hours, to make the trip without the wind. Then 660/t= v or vt= 660. With the tail wind the speed is v+ 60 and the time for the trip is t- 1/10 (60 minutes is 1/10 hour). Then 660/(t- 1/10)= v+ 60 or 660= (t- 1/10)(v+ 60)= tv+ 60t+ v/10+ 6.

    Solve the two equations vt= 660 and tv+ 60t+ v/10+ 6= 660.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Not sure what subject this comes under, and not HW, just a problem.
Loading...