1. Projectile Motion
Level 1 Physics

2. Objectives and Essential Questions
Apply definitions of displacement, velocity, and acceleration as they relate to two dimensions
Demonstrate proficiency in problem solving using kinematic equations as they apply to motion in two dimensions
Predict the horizontal displacement of a projectile launched horizontally (Laboratory)
Essential Questions
How can we describe motion in two dimensions?
How can we predict motion in two dimensions?

3. The Definition
A projectile is any object that is projected and continues to move due
to its own inertia
Gravity is the only item acting
on the object
Thrown at
an angle
Vertically
downward
Vertically
upward

4. The Motion of a Projectile - Horizontal
In the absence of gravity, a projectile will travel at the same speed
and in the same direction
Gravity is unable to effect
the horizontal motion of
a projectile

5. The Motion of a Projectile - Vertical
Gravity only plays a role in the vertical
direction of projectiles – accelerates the object
Gravity-free
path

6. Combining the Components
Together, these components produce what is called a trajectory or path. This path is parabolic in nature.
Component
Magnitude
Direction
Horizontal
Constant
Vertical
Changes

7. Horizontally Launched Projectiles
Projectiles which have NO upward trajectory and NO initial VERTICAL velocity.

8. Horizontally Launched Projectiles
To analyze a projectile in 2 dimensions we need 2 equations. One for the “x” direction and one for the “y” direction.
Remember, the velocity is CONSTANT horizontally, so that means the acceleration is ZERO!
Remember that since the projectile is launched horizontally, the INITIAL VERTICAL VELOCITY is equal to ZERO.

9. Horizontally Launched Projectiles
Example: A plane traveling with a horizontal velocity of 100 m/s is 500 m above the ground. At some point the pilot decides to drop some supplies to designated target below. (a) How long is the drop in the air? (b) How far away from point where it was launched will it land?
What do I know?
What I want to know?
vox=100 m/s
t = ?
y = 500 m
x = ?
voy= 0 m/s
g = -9.8 m/s/s
1010 m
10.1 seconds

10. Vertically Launched Projectiles
NO Vertical Velocity at the top of the trajectory.
Vertical Velocity decreases on the way upward
Vertical Velocity increases on the way down,
Horizontal Velocity is constant
Component
Magnitude
Direction
Horizontal
Constant
Vertical
Decreases up, top, Increases down
Changes

11. Vertically Launched Projectiles
Since the projectile was launched at a angle, the velocity MUST be broken into components!!! vo
voy q
vox

12. Vertically Launched Projectiles
There are several things you must consider when doing these types of projectiles besides using components. If it begins and ends at ground level, the “y” displacement is ZERO: y = 0

13. Vertically Launched Projectiles
You will still use kinematic equations, but YOU MUST use COMPONENTS in the equation. vo
voy q
vox

14. Example
A place kicker kicks a football with a velocity of 20.0 m/s and at an angle of 53 degrees.
(a) How long is the ball in the air?
(b) How far away does it land?
(c) How high does it travel?
vo=20.0 m/s
q = 53

15. Example
What I know
What I want to know
vox=12.04 m/s
t = ?
voy=15.97 m/s
x = ?
yo = 0
ymax=?
g = m/s/s
A place kicker kicks a football with a velocity of 20.0 m/s and at an angle of 53 degrees.
(a) How long is the ball in the air?
3.26 s

16. Example
A place kicker kicks a football with a velocity of 20.0 m/s and at an angle of 53 degrees.
(b) How far away does it land?
What I know
What I want to know
vox=12.04 m/s
t = 3.26 s
voy=15.97 m/s
x = ?
y = 0
ymax=?
g = m/s/s
39.25 m

17. Example What I know What I want to know t = 3.26 s x = 39.25 m y = 0
vox=12.04 m/s
t = 3.26 s
voy=15.97 m/s
x = m
y = 0
ymax=?
g = m/s/s
A place kicker kicks a football with a velocity of 20.0 m/s and at an angle of 53 degrees.
(c) How high does it travel?
CUT YOUR TIME IN HALF!
13.01 m