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Multivariable Calculus

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Initial Velocity of Projectile

MVCALC-GPG13E

After being hit, a baseball has an initial speed of $90$ miles per hour, and it moves in a vertical plane that we define to be the $xy$-plane so that at the beginning, it moves at an angle of $45^{\circ}$ with respect to the ground.

What is the initial velocity of the baseball?

A

$t{\bf i} + t{\bf j}$

B

$45\sqrt{2} {\bf i} + 45\sqrt{2} {\bf j}$

C

$t\frac{\sqrt{2}}{2} {\bf i} + t\frac{\sqrt{2}}{2}{\bf j}$

D

$90\sqrt{2} {\bf i} + 90\sqrt{2} {\bf j}$

E

$45\sqrt{2} {\bf i} + 45\sqrt{2} {\bf j}+ 45\sqrt{2} {\bf k}$