1. Limited time only! Sign up for a free 30min personal 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!

Difference in flight time for two planes with different velocity profiles

Tags:
  1. Jan 25, 2017 #1
    1. The problem statement, all variables and given/known data
    ** sorry, answer in the book doesn't make sense **
    A british concord and a French concord flew in opposite directions around the world, a distance of 40K km. The BC covered half its distance at 2500 km/h, and the other half at 1000km/h. The FC spent half its flight time at 2500 km/h and the other half at 1000 km/h. Which concorde completed the trip first and by how many hours did it beat the oher?
    2. Relevant equations
    V= d/t.

    3. The attempt at a solution
    Time for BC

    20 000km /t = 2500
    t= 20 000/2500
    t= 8 hours
    20 000km/1000=t
    20 hrs = t
    Total time = 28 hours

    Time for FC
    40 000 = 2500 (t/2) + 1000 (t/2)
    40 000 = 3500 (t/2)
    (40 000/3500)2= t
    22.9 hours =t

    Looking at this, the french concorde got there first and beat the British concord by 5.1 hours. At the back, the difference I got is correct, it is 5.1 hours, but it says the British concord got there first. How? The BC trip was 28 hours, the FC trip was 22.9 unless I did something wrong ?

    *I'm sorry this is probably a dumb question, but I don't remember if my teacher said the answer at the back was incorrect or not, so this is me reconfirming my assumption that the book is wrong *
     
  2. jcsd
  3. Jan 25, 2017 #2
    It looks like the book is wrong.
     
  4. Jan 25, 2017 #3

    FactChecker

    User Avatar
    Science Advisor
    Gold Member

    Your answer looks ok to me.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Difference in flight time for two planes with different velocity profiles
Loading...