PROJECTILE MOTION LPPACS Physics

Mr. Schmidt

What are projectiles? v Examples:

Projectile Motion v When an object is thrown or launched

into the air, it undergoes projectile motion. The pathway of any projectile is a parabola (excluding air resistance).

Project This! v A projectile is any object that moves through the

air or through space, acted on only by gravity (and air resistance, if any)

v Gravity causes launched projectiles to move in a curved path and then hits the ground. Without gravity, the projectile would move in a straight path.

v Without air resistance the time it takes a launched projectile to go up would equal the time it takes to come down.

Factors Affecting Projectile Motion

With No Force of the Earth…

What Do We Actually See?

Projectiles From an Airplane

Part 1. Motion of Objects Projected

Horizontally With a Zero Launch Angle

(Zero Launch)

vi

x

y

x

y

What’s Going On With x and y?

What Do You Notice About Vx and Vy?

What About When Launched at an Angle?

x

y

• Motion is accelerated (y)

• a = g = -9.8 m/s2

• The horizontal (x) component of velocity is constant (ax = 0 m/s2)

• The horizontal and vertical motions are independent of each other, but they have a common time

g = -9.8 m/s2

ANALYSIS OF MOTION ASSUMPTIONS:

•  x-direction (horizontal): uniform, constant velocity

•  y-direction (vertical): accelerated motion

•  no air resistance

QUESTIONS:

•  What is the initial horizontal velocity?

•  What is the total time of the motion?

•  What is the horizontal range?

•  What is the final velocity?

Which one was thrown fastest?

Steps in Solving Projectile Problems v 1. Determine the type of problem (Ex. Zero

Launch Angle, etc.) v 2. Break any velocities into components v 3. List your knowns and unknowns v 4. Choose a direction to start in and equation v 5. Solve

Example! Woot! Mr. Schmidt tests out his skills of launching water

balloons off of the roof of the school. He launches a balloon horizontally off of the top of the 24.0 m high building and it reaches a range of 86.0 m. ü How fast did he launch the balloon? ü How long was the balloon in the air? ü With what velocity did it hit the ground?

Mr. Schmidt tests out his skills of launching water balloons off of the roof of the school. He launches a balloon horizontally off of the top of the 24.0 m high building and it reaches a range of 86.0 m. ü  How fast did he launch the balloon? ü  How long was the balloon in the air? ü  With what velocity did it hit the ground?