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!

Relative Velocity Bird Flying Problem

  1. Aug 7, 2006 #1

    danago

    User Avatar
    Gold Member

    Hey. Ive done this question, but my answer is only partly correct according to the answer book. Heres the question:

    "To a bird flying at 20km/h on a bearing of 160 degrees, the wind seems to be coming from the south at 25km/h. Find the true velocity of the wind"

    ok. I said that B is the velocity of the bird, W is the velocity of the wind, and O is the origin. I then found that:

    [tex]
    \begin{array}{l}
    \overrightarrow {OB} = \left( {\begin{array}{*{20}c}
    {20\cos 70} \\
    { - 20\sin 70} \\
    \end{array}} \right) \\
    \overrightarrow {BW} = \left( {\begin{array}{*{20}c}
    0 \\
    {25} \\
    \end{array}} \right) \\
    \end{array}
    [/tex]

    I then said that:
    [tex]
    \begin{array}{l}
    \overrightarrow {BW} = \overrightarrow {BO} + \overrightarrow {OW} \\
    \left( {\begin{array}{*{20}c}
    0 \\
    {25} \\
    \end{array}} \right) = - \left( {\begin{array}{*{20}c}
    {20\cos 70} \\
    { - 20\sin 70} \\
    \end{array}} \right) + \overrightarrow {OW} \\
    \overrightarrow {OW} = \left( {\begin{array}{*{20}c}
    {20\cos 70} \\
    {25 - 20\sin 70} \\
    \end{array}} \right) \\
    \end{array}
    [/tex]

    I then found the answer to be 9.24km/h on a bearing of 48 degrees, but the answer says 9.24hm/h on a bearing of 228 degrees. Have i gone wrong somewhere? is the book wrong? any help is greatly appreciated.

    Thanks,
    Dan.
     
  2. jcsd
  3. Aug 7, 2006 #2

    danago

    User Avatar
    Gold Member

    Ok thanks to anyone who read this and would have helped, but i seem to have solved my own problem :P The answer gave the velocity of the wind coming FROM 228 degrees. The answer i obtained was the wind going TO a direction of 48 degrees.

    Guess id better learn to read properly :P
     
  4. Aug 7, 2006 #3
    oh yay good job 10chars
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Relative Velocity Bird Flying Problem
  1. Relative velocity (Replies: 2)

Loading...