Calculus (3rd Edition)

Published by W. H. Freeman
ISBN 10: 1464125260
ISBN 13: 978-1-46412-526-3

Chapter 14 - Calculus of Vector-Valued Functions - 14.5 Motion in 3-Space - Exercises - Page 744: 8

Answer

Please see the figure attached. Dashed arrows indicate the direction of motions. Velocity vectors at $t=0$ and $t=1$: ${\bf{v}}\left( 0 \right) = \left( {0, - 1} \right)$ ${\bf{v}}\left( 1 \right) = \left( { - 2, - 1} \right)$ Acceleration vectors at $t=0$ and $t=1$: ${\bf{a}}\left( 0 \right) = {\bf{a}}\left( 1 \right) = \left( { - 2,0} \right)$

Work Step by Step

We have ${\bf{r}}\left( t \right) = \left( {1 - {t^2},1 - t} \right)$ for $ - 2 \le t \le 2$. The velocity vector: ${\bf{v}}\left( t \right) = {\bf{r}}'\left( t \right) = \left( { - 2t, - 1} \right)$ So, ${\bf{v}}\left( 0 \right) = \left( {0, - 1} \right)$ and ${\bf{v}}\left( 1 \right) = \left( { - 2, - 1} \right)$. The acceleration vector: ${\bf{a}}\left( t \right) = {\bf{r}}{\rm{''}}\left( t \right) = \left( { - 2,0} \right)$ Notice that the acceleration vector is constant. So, ${\bf{a}}\left( 0 \right) = {\bf{a}}\left( 1 \right) = \left( { - 2,0} \right)$. As can be seen in the figure, the dashed arrows indicate the direction of motions.
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