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Revision as of 16:24, 11 April 2010 (edit) Ian (Talk | contribs) (New page: We insert <math>t=0\ \text{s}</math> in the expression for the position vector to find the point where the frisby waqs thrown from. <math>\begin{align} & \mathbf{r}=\left( 5\times 0-{{0...) ← Previous diff		Current revision (14:56, 14 May 2010) (edit) (undo) Ian (Talk | contribs)
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Line 1:		Line 1:
	We insert		We insert
	<math>t=0\ \text{s}</math>		<math>t=0\ \text{s}</math>
-	in the expression for the position vector to find the point where the frisby waqs thrown from.	+	in the expression for the position vector to find the point where the frisby was thrown from.
Line 7:		Line 7:
	& \mathbf{r}=\left( 5\times 0-{{0}^{2}} \right)\mathbf{i}+\left( 7\times 0 \right)\mathbf{j}+0\mathbf{k} \\		& \mathbf{r}=\left( 5\times 0-{{0}^{2}} \right)\mathbf{i}+\left( 7\times 0 \right)\mathbf{j}+0\mathbf{k} \\
	& \\		& \\
-	& =-24\mathbf{i}+56\mathbf{j}+0\mathbf{k}\ \text{m} \\	+	& =0\mathbf{i}+0\mathbf{j}+0\mathbf{k}\ \text{m}\\
	\end{align}</math>		\end{align}</math>
		+
		+	Thus the point where the frisby was thrown from is the origin.
		+
		+	Using the result from part b)
		+
		+	<math>\begin{align}
		+	& \mathbf{r}=-24\mathbf{i}+56\mathbf{j}+0\mathbf{k}\ \text{m}
		+	\end{align}</math>
		+
		+	we get the distance from the origin to where it hits the ground is
		+
		+	<math>\sqrt{{{\left( -24 \right)}^{2}}+{{56}^{2}}}=\sqrt{576+3136}=\sqrt{3712}=60\textrm{.}9\ \text{m}</math>

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Current revision

We insert \displaystyle t=0\ \text{s} in the expression for the position vector to find the point where the frisby was thrown from.

\displaystyle \begin{align} & \mathbf{r}=\left( 5\times 0-{{0}^{2}} \right)\mathbf{i}+\left( 7\times 0 \right)\mathbf{j}+0\mathbf{k} \\ & \\ & =0\mathbf{i}+0\mathbf{j}+0\mathbf{k}\ \text{m}\\ \end{align}

Thus the point where the frisby was thrown from is the origin.

Using the result from part b)

\displaystyle \begin{align} & \mathbf{r}=-24\mathbf{i}+56\mathbf{j}+0\mathbf{k}\ \text{m} \end{align}

we get the distance from the origin to where it hits the ground is

\displaystyle \sqrt{{{\left( -24 \right)}^{2}}+{{56}^{2}}}=\sqrt{576+3136}=\sqrt{3712}=60\textrm{.}9\ \text{m}