1. Projectile Motion Mr. Duke - Horizontal Projectiles PAP Physics
Page 98 – 101 Holt Physics Book in class

2. What is a projectile?
Any object that moves through the air or through space acted on ONLY by gravity.

3. Inertial or Gravity-free Path

4. Horizontal Projectiles w/ Gravity
vx = vix = vfx
This means the velocity in the x direction remains constant.

5. x and y components of motion are INDEPENDENT!
ie: any force in the horizontal DOES NOT affect the vertical, and vice versa.
A chart to help keep everything organized
x unknowns
dx =
vx =
t =
y unknowns
dy =
viy =
vfy =
a = -9.8 m/s2
t =

7. Example # 1
Imagine you are sitting in a car throwing a ball straight up.
If the car is moving at a constant velocity where will the ball land?
The ball will land at the same point it was launched because everything in the car is going the same speed in the horizontal direction.
If the car slams on the brakes where will the ball land?
The ball will land forward from the launch point because everything in the car is slowing down in the horizontal direction but the ball has the same vx that the ball was launched.

8. Example # 2
A zoologist standing on a cliff aims a gun at a monkey hanging in a tree in the distance. The barrel of the gun is pointing at the monkey and is horizontal.
Does the zoologist hit the monkey? Why or why not? The zoologist does not hit the monkey because the only falling object is the bullet.
At the exact moment the zoologist pulls the trigger the monkey lets go of the branch. Does the zoologist hit the monkey? Why or why not?
The bullet fired by the zoologist will hit the monkey. The reason is the bullet and the monkey fall at the same rate. What is that rate? The rate they fall is under gravity; -9.8 m/s2.

9. Example #3

10. Example #3 (cont.)

11. Example #3 (cont)

19. Example #5
An airplane traveling 1050 m above the ocean at 125 km/hr is to drop a box of supplies to the shipwrecked victims below.
How many seconds before being directly overhead should the box be dropped?
How far from the victims is the plane when the box is dropped?