Processing Math: Done
Solution 19.8d
From Mechanics
(Difference between revisions)
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The expression for the position vector <math>\mathbf{r}</math> has been obtained in part b). | The expression for the position vector <math>\mathbf{r}</math> has been obtained in part b). | ||
- | <math>\mathbf{r}=\left( 40t \right)\mathbf{i}+\left( - | + | <math>\mathbf{r}=\left( 40t \right)\mathbf{i}+\left( {-{t}^{2}}+400 \right)\mathbf{j}</math> |
If the aeroplane is due east of the origin its position in the north-south direction must be zero, which means the <math>\mathbf{j}</math> component of the position vector must be zero. | If the aeroplane is due east of the origin its position in the north-south direction must be zero, which means the <math>\mathbf{j}</math> component of the position vector must be zero. | ||
<math>\begin{align} | <math>\begin{align} | ||
- | & - | + | & {-{t}^{2}}+400=0 \\ |
& \\ | & \\ | ||
- | & t= | + | & t=20\text{ s} \\ |
\end{align}</math> | \end{align}</math> |
Current revision
The expression for the position vector
40t
i+
−t2+400
j
If the aeroplane is due east of the origin its position in the north-south direction must be zero, which means the