Solution 19.8c

From Mechanics

(Difference between revisions)
Jump to: navigation, search
Line 1: Line 1:
-
The expression for the position vector <math>\mathbf{r}</math> has been obtained in part b),
+
The expression for the velocity <math>\mathbf{v}</math> has been obtained in part b).
 +
 
 +
<math>\mathbf{v}=\left( 40 \right)\mathbf{i}+\left( -2t \right)\mathbf{j}</math>
 +
 
 +
If the aeroplane is travelling south this is in the negative <math>\mathbf{j}</math> direction.
 +
 
 +
If the aeroplane is travelling east this is in the positive <math>\mathbf{i}</math> direction.
 +
 
 +
Thus if the aeroplane is travelling south east the <math>\mathbf{i}</math> component of the velocity must equal the minus <math>\mathbf{j}</math> component of the velocity.
 +
 
 +
<math>\begin{align}
 +
& 40=-(-2t) \\
 +
& \\
 +
& t=20\text{ s} \\
 +
\end{align}</math>

Revision as of 17:06, 11 October 2010

The expression for the velocity \displaystyle \mathbf{v} has been obtained in part b).

\displaystyle \mathbf{v}=\left( 40 \right)\mathbf{i}+\left( -2t \right)\mathbf{j}

If the aeroplane is travelling south this is in the negative \displaystyle \mathbf{j} direction.

If the aeroplane is travelling east this is in the positive \displaystyle \mathbf{i} direction.

Thus if the aeroplane is travelling south east the \displaystyle \mathbf{i} component of the velocity must equal the minus \displaystyle \mathbf{j} component of the velocity.

\displaystyle \begin{align} & 40=-(-2t) \\ & \\ & t=20\text{ s} \\ \end{align}

Retrieved from "http://wiki.sommarmatte.se/wikis/2009/bridgecoursemechanics/index.php/Solution_19.8c"