1. Physics of Projectile Motion
Exploding fireworks follow a parabolic trajectory.

2. What’s wrong with this picture ?
Answer: It never happens ! Only when
there is no gravity.

3. Why do projectiles fly in a parabola?

4. A History of Projectile Motion
Aristotle:
The canon ball travels in a
straight line until it lost its
‘impetus’.
Galileo:
- a result of Free Fall Motion
along y-yaxis and Uniform
Motion along x-axis.

5. Projectile Motion = Sum of 2 Independent Motions
1. Along x, the projectile travels with constant velocity.
vx=vxo x = vxot
Along y, the projectile travels in free-fall fashion.
vy = vyo – gt y = vyot – (1/2) gt2 , g= 9.8 m/s2
Projectile motion = a combination of uniform motion along x and
uniformly accelerated motion (free fall) along y.

6. What’s the similarity between a freely-falling ball and a projectile ?
uniform motion
Projectile
motion
vertical
motion x
A dropped ball falls in the same time as a ball shot horizontally.
Along the vertical, their motions are identical (uniformly
accelerated motion (free-fall).
Along the horizontal, notice the ball fired horizontally covers the
Same distance in the same unit time intervals (uniform motion along x)

7. v vy vx Velocity Components at various points of the Trajectory 
vertical component  vy v
Net velocity vx
Horizonal component
Above: Vectors are
added in geometric
Fashion.
Launch speed = Return Speed.
Speed is minimum at apex of parabolic trajectory.

8. At what angle do I launch for Maximum Range ?
Need to stay in air for the longest time,
and with the fastest horizontal velocity component
Answer: 45°

9. Everyday Examples of Projectile Motion
Baseball being thrown
Water fountains
Fireworks Displays
Soccer ball being kicked
Ballistics Testing