1. Over the Edge

2. Projectiles
A projectile is an object upon which the only force is gravity.
A projectile, however, may move in different directions based on its initial trajectory & velocity. Remember forces are not required for motion to occur.

3. Horizontally Launched Projectiles
Scenario 1: In the absence of gravity a horizontally projected cannonball continues its horizontal motion at a constant velocity. Scenario 2: In the presence of gravity a dropped cannonball accelerates downwards at 9.8 m/s/s Scenario 3: What would occur to a cannonball projected horizontally in the presence of gravity?
Scenario 3
Horizontal Motion
Vertical Motion
Forces?
Y or N
Direction?
Acceleration?
Velocity?
Constant or changing?
Horizontal NO, NO, Constant
Vertical Yes (g down), Yes (9.8 m/s/s), Changing

4. Horizontal & Vertical Components
If we project a cannonball horizontally at 20 m/s in the presence of gravity what can we expect to happen in 5 seconds?
How far would the cannonball travel horizontally after 5 seconds?
Time (s)
Horizontal
Velocity
Vertical Velocity 1
20 m/s
9.8 m/s/s 2 3 4 5
Horizontal STAYS 20 m/s
Vertical Velocity CHANGES 19.6, 29.4, 39.2, and 49 m/s
100 meters

5. Important Equations y: vertical displacement y=½gt2
x: horizontal displacement
x= vixt
vix: initial horizontal velocity

6. Equations Remember ay=-9.8m/s/s
Horizontal Components
x=vixt + .5axt2
vfx=vix + axt
vfx2=vix2 + 2axx
x= horizontal displacement
vfx=final horiz. Velocity
ax= horizontal acceleration
vix= initial horiz. Velocity
t=time
Vertical Components
y=viyt + .5ayt2
vfy=viy + ayt
vfy2=viy2 + 2ayy
y= vertical displacement
vfy=final vert. velocity
ay= vertical acceleration
viy= initial vertical Velocity
t=time

7. Using Trig to find Velocity
vix=vicos(Θ) Θ=angle made with horizon viy=visin(Θ) Θ=angle made with horizon

8. Practice Problem Race kicks a football with an initial velocity of 25m/s at an angle of 45° to the horizon. Determine the time of flight, horizontal displacement, and the peak height of the football.
Horizontal Components vix=? vfx=? ax=? x=?
Vertical Components viy=? vfy=? ay=? y=? t-=?
Vix=17.7 m/s
Vfx=17.7 m/s
Ax=0m/s/s
Viy=17.7m/s
Vfy=-17.7m/s
Ay=-9.8m/s/s
X=63.9m
Y=15.98m
T=3.61s