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) | \(21 \sin 47 = (21) \sin47 = 15.36 \;m/s\) | \(-21 \cos 47 = (21) \cos47 = 14.32 \;m/s\) |