Projectile Motion

1
Projectile Motion
Once launched, what path will the cannon ball
follow?
This was a problem contemplated by Galileo
2
He investigated vertical motion by rolling balls
down slopes of varying degrees and extrapolating
the results to apply to right angles
3
He deduced that the distance fallen, s, is
proportional to the time squared s a t2
So a body in freefall is being accelerated at a
constant rate.
4
He also thought that any horizontal motion would
continue unchanged in the absence of a retarding
force.
5
Galileo then described projectile motion as a
combination of both vertical and horizontal
motions acting independently
6
By combining both vertical and horizontal
motions, Galileo was able to establish the path
of the cannon ball
7
The path of a projectile is a combination of an
independent vertical motion and an independent
horizontal motion
Resulting in a parabola.
8
When we analyse projectile problems, we do the
same as Galileo Consider the vertical motion
using a constant acceleration 9.8 ms-2 Consider
the horizontal motion with no acceleration,
therefore horizontal velocity does not change, vx
ux.
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Equations
Horizontal
Vertical
v u at
v2y u2y 2ayDy
v2x u2x
Dx uxt
Dy uyt 1/2ayt2
ax 0
ay 9.8 ms-2
At maximum height
vy 0