1. Projectiles

2. Bellwork Complete Wednesday and Thursday’s bell work
Do not play with materials in basket

3. To do: Place the images into 2 categories Projectile Motion
Non-Projectile Motion

4. A Projectile is . . .
An object thrown or launched into the air that is subject only to gravity

5. Projectiles include: Throwing a baseball shooting an arrow
hitting golf balls
long jumpers

6. To do:
Using the materials in your basket, build an apparatus that will launch the marshmallow with a parabolic trajectory
Think about:
How does the velocity of the marshmallow change as it travels through the air?
Is there a difference between the velocity in the x direction and the velocity in the y direction?
What is the only force acting on the cotton ball once it has been launched?
How can you make the cotton ball go higher? Further?

7. Bellwork
1. What is the acceleration of a tossed ball at the top of its path?
2. How do you find the displacement of an object from a velocity time graph?
3. Draw a position time graph that shows
Object traveling with constant velocity
Object decelerating
Object at rest

8. Projectile motion Has both a horizontal and vertical component (part)
These components are independent of one another

9. Trajectory The path of a projectile is called a trajectory
the shape of a projectile’s path is a parabola

10. Horizontal motion A projectile moves forward due to INERTIA
Inertia is the reluctance of an object to change its motion

11. Horizontal motion
A projectile continues forward at constant speed because no HORIZONTAL FORCE acts on it
The velocity in the horizontal direction remains the same throughout flight

12. Vertical motion
Gravity pulls on any object and causes it to return to earth
This means that the vertical velocity changes
This motion is just like an object in free fall

13. Projectiles launched horizontally
Half picture projectiles

14. Projectile Velocity
Separate the motion into x and y components (parts)
When an object is launched horizontally, the VERTICAL velocity is 0 m/s

15. Vx
Actual path vy

16. The acceleration of the object in the y direction is due to gravity (like free fall)
Use kinematic equations to solve for unknowns in both the x and y directions

17. Mythbusters

18. Useful Distance Equations
For horizontal distance: OR
This equation for average velocity can also be used for finding velocity in the horizontal (x) direction.

19. Useful Distance Equations
For Vertical Distance

20. Useful Velocity Equations
For vertical velocity

21. Useful Velocity Equations
Remember that horizontal velocity remains the same throughout flight

22. Time of flight
The time of flight can be determined using kinematic equations used for free fall. Remember, the only force acting on an object once it has been launched is gravity.

23. Example:
A stone is thrown horizontally at 15 m/s from the top of a cliff 44m high.
A. How long does the stone take to reach the bottom of the cliff?
B. How far from the base of the cliff does the stone strike the ground?

24. Time Solution

25. Distance Solution

26. Given Information v = 15 m/s vi = 0 m/s d=? d = 44 m, down
Horizontal Values
Vertical Values
v = 15 m/s
vi = 0 m/s
d=?
d = 44 m, down
Constant speed
a = -9.8 m/s2 t=

27. Time Solution
-44m = 1/2(-9.8m/s2)t2
t = 3 s

28. Distance solution:
d = vt
d = 15 m/s x 3.0 s
d = 45 m

29. Upwardly Launched Projectiles (at an angle)
The result of simultaneous horizontal and vertical motion is a curved path