Problem 4-21-Projectile - Part 2 - A

A football is placed on a line $25\; m$ from the goalpost. The placement kicker kicks the ball directly toward the goalpost, giving it a velocity of $21.0\; m/s$ at an angle of $47.0^\circ$ above the horizontal. The horizontal bar of the goalpost is $3.0\; m$ above the field. How far above or below the horizontal bar of the goalpost will the ball travel?

A. Correct

We need the $x$ and $y$ components of the initial velocity. They are:

Answer $v_{0_x}$ $v_{0_y}$
(A) $21 \sin 47 = (21) \sin47 = 15.36\; m/s$ $21 \cos 47 = (21) \cos47 = 14.32\; m/s$
(B) $21 \cos 47 = (21) \cos47 = 14.32 \;m/s$  $-21 \sin 47 = (21) \sin47 = 15.36 \;m/s$
(C) $21 \cos 47 = (21) \cos47 = 14.32 \;m/s$ $21 \sin 47 = (21) \sin47 = 15.36 \;m/s$
(D) $21 \sin 47 = (21) \sin47 = 15.36 \;m/s$ $-21 \cos 47 = (21) \cos47 = 14.32 \;m/s$