Physics of Projectile Motion
Exploding fireworks follow a parabolic trajectory.

Answer: It never happens ! Only when there is no gravity.

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.

Projectile Motion = Sum of 2 Independent Motions
1. Along x, the projectile travels with constant velocity.
v x
= v xo x = v xo t
2. Along y, the projectile travels in free-fall fashion.
v y
= v yo
– gt y = v y ot – (1/2) gt 2 , g= 9.8 m/s 2
Projectile motion = a combination of uniform motion along x and uniformly accelerated motion (free fall) along y.

What’s the similarity between a freely-falling y ball and a projectile ?
uniform motion
Projectile motion vertical motion
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).
x
Along the horizontal, notice the ball fired horizontally covers the
Same distance in the same unit time intervals (uniform motion along x)

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

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°

Everyday Examples of Projectile Motion
1. Baseball being thrown
2. Water fountains
3. Fireworks Displays
4. Soccer ball being kicked
5. Ballistics Testing