Hey. Ive done this question, but my answer is only partly correct according to the answer book. Heres the question:(adsbygoogle = window.adsbygoogle || []).push({});

"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.

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# Relative Velocity Bird Flying Problem

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