1. Projectile
An object that is launched by a force and continues to move by its own inertia. The only force acting on it is gravity. (in free fall)

2. Trajectory
The path that a projectile traces.

3. 4 Types of Projectile Motion
Dropped (straight down, (a = g)
Trajectory is straight line down
vy = gt

4. 4 Types of Projectile Motion
Dropped (straight down, a = g)
10.00
3.80
1.80
0.00
-9.8 m/s2

5. Dropped vs Thrown Straight Down
Dropped Thrown
time
time
velocity
velocity
slope = g (both) and vf = vi + gt

6. 4 Types of Projectile Motion
2. Launched straight up (then falls down, a = g)
Trajectory is a straight line up & down
video
-9.8 m/s2
-9.8 m/s2
-9.8 m/s2

7. 4 Types of Projectile Motion
2. Launched straight up
3.80
1.80
0.00
-9.8 m/s2

8. 4 Types of Projectile Motion
3. Launched horizontally (a = g)
Trajectory is half a parabola

9. 4 Types of Projectile Motion
3. Launched horizontally, cont
Horizontal Velocity
3.80
1.80
0.00
Vertical Velocity
-9.8 m/s2

10. 4 Types of Projectile Motion
3. Launched horizontally, cont.
Independence of horizontal and vertical motion
Only when they act in concert do we get a true parabolic trajectory
Motion equations can be used in one dimension only

11. 4 Types of Projectile Motion
3. Launched horizontally
Equations
Since velocity does not change in x direction, our average velocity equation works… vx = dx/t
vy = viy + at
dy = viyt + .5at2
Sample problem next or straight to cliff diving?

12. Sample Problem
A stone is thrown horizontally from the top of a cliff with a velocity of 15 m/s. It takes 3 s for the rock to land.
a) How high is the cliff?
b) How far from the base of the cliff does the stone strike the ground?

13. Sample Problem, cont.
A stone is thrown horizontally from the top of a cliff with a velocity of 15 m/s. It takes 3 s for the rock to land.
a) How high is the cliff?
Given
Unknown
Equation
Substitute
Solve
Ask: How high is in x or y direction? Y, so we need givens for y. Ans 44.1 m

14. Sample Problem
A stone is thrown horizontally from the top of a cliff with a velocity of 15 m/s. It takes 3 s for the rock to land.
b) How far from the base of the cliff does the stone strike the ground?
Given
Unknown
Equation
Substitute
Solve
Ans 45 m

15. 4 Types of Projectile Motion
3. Launched horizontally
Cliff Diving on Mars vx vy v
v = vx2 + vy2

16. 4 Types of Projectile Motion
4. Launched at an angle (a = g)
What do you notice about the
- vertical motion? - horizontal motion?

17. 4 Types of Projectile Motion
4. Launched at an angle, cont…
Horizontal velocity
Vertical velocity

18. 4. Launched at an angle (cont)…
acceleration

19. Kinematics of Projectile Motion

20. Draw position vectors

21. Draw acceleration vectors
a = -9.8 m/s2
a = -9.8 m/s2
a = -9.8 m/s2
a = -9.8 m/s2
a = -9.8 m/s2
a = -9.8 m/s2 EVERYWHERE!!!
a = -9.8 m/s2
a = -9.8 m/s2

22. Draw velocity component vectorsvy vx vy vx vx vy vy vx vx vx vy

23. Actual velocity resultant vectorsvy v vx vy vx vx vy v vy vx vx v vx vy

24. Projectile Motion Summary
Object has:
Horizontal Uniform motion
Vertical Acceleration due to Gravity affects motion

25. A hunter, a monkey and a coconut Doing it for real Shoot the Monkey

26. Question?
Suppose a rescue airplane drops a relief package while it is moving with a constant horizontal speed at an elevated height. Assuming that air resistance is negligible, where will the relief package land relative to the plane? a. below the plane and behind it. b. directly below the plane c. below the plane and ahead of it

27. It will take 4 seconds to fall 78.4 meters
Another Question?
Anna Litical drops a ball from rest from the top of 78.4-meter high cliff. How much time will it take for the ball to reach the ground?
It will take 4 seconds to fall 78.4 meters

28. Worksheet