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!

Homework Help: Basically we were given vector problems, HELP!

  1. May 13, 2009 #1
    1. The problem statement, all variables and given/known data
    A pilot wants his groundspeed to be 260mph on a bearing of 180 degrees. An east wind is blowing at 65mph. What should his airspeed and heading be so that the wind will blow him back onto his intended course?

    2. Relevant equations

    3. The attempt at a solution
    I drew it out, but apparently its wrong. I drew a right triangle with the wind as the horizontal and 260mph as the vertical and thats all i got. Please explain with concept too. Thanks
  2. jcsd
  3. May 13, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Concept is called vector addition. The unknown desired heading should be the vector that when added to "east wind is blowing at 65mph" yields, "260mph on a bearing of 180 degrees". Split them into NS and EW components.
  4. May 14, 2009 #3


    User Avatar
    Science Advisor

    Nothing wrong with that. Taking "east" to the right and "south" downward, draw a line to the right with length "65 mph" and, at the end of that, draw a line downward with length "260 mph". That gives you a right triangle with legs of length 65 and 260. The airspeed is the length of hypotenuse. The Pythagorean theorem gives you that. Which angle you use depends on how you want to write the course. If you want to write it as a compass reading in degrees from north, it will be 90 plus the angle in the upper left of the triangle, where you started. If you want to write it as "degrees east of south", it will be 90 degrees minus that angle. In either case you can use the tangent function to find "that angle".
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook