Transcript ProjectileMotionTopic

Projectile Motion!
Question:
What is a projectile?
Answer:
An object which moves in
two directions above the
Earth at the same time,
with no means of selfpropulsion!
• Trajectory = The actual flight path of the object.
Motion is Relative!
The trajectory at any point can be
broken down into two components of
motion:
Projectile Motion!
• To simplify calculations, we assume that, once an
object is projected, the only force acting on the
object is Gravity!
• What this implies is that there is no air resistance.
This means that no force acts horizontally, so, once
projected, horizontal velocity stays constant!
• We can also assume that any projectile will have the
same rate of acceleration, g (-9.81 m/s2), IN THE
VERTICAL DIRECTION ONLY, throughout its entire
flight.
Projectile Motion!
There are two basic types of P.M.:
1. Horizontal (simple) Projection – an
object is projected parallel to the
ground from some height, so its initial
velocity in the y-direction = 0 (similar
to freefall)!
2. Projection at an Angle – more complex,
an object is projected at some angle
from horizontal, and therefore has a
non-zero initial velocity in the ydirection!
Horizontal Projectile Motion!
Basic assumptions:
1. Initial velocity in the y-direction
(V0y) = 0 (similar to freefall), and
acceleration in the y-direction is
-9.81 m/s2.
2. The initial velocity is only in the
horizontal direction (V0x), and, since
the air resistance is zero, V0x stays
constant for the entire trajectory!
Horizontal Projectile Motion!
Basic assumptions:
3. Since Vx is unaffected by vertical
acceleration, and vice-versa, we can
say the two components of motion are
independent, and use our kinematics
equations for each direction!
4. Since Vx doesn’t change, we can let
V0x = Vx , and use the equation
V = ∆x / t
Horizontal Projectile Motion!
Basic assumptions:
5. Make sure to separate your x and y info
to calculate correct answers! The only
data shared between the two
directions is time. It takes the same
amount of time to fall vertically as it
does to travel horizontally!
Horizontal Projectile Motion Diagram!