# PROJECTILE MOTION by dffhrtcv3

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```									PROJECTILE MOTION

CH 3 – 2 DIMENSIONAL MOTION
A gun with a muzzle velocity of 1000 ft/sec
is shot horizontally. At the same time an identical
bullet is dropped alongside the gun. Which bullet
will hit first?
A gun with a muzzle velocity of 1000 ft/sec
is shot horizontally. At the same time an identical
bullet is dropped alongside the gun. Which bullet
will hit first?

Guess what! They both land at the SAME time
but at different places. What’s different?
Projectile Motion
   The difference is that one bullet has
INITIAL VELOCITY.
Projectile Motion
   The difference is that one bullet has
INITIAL VELOCITY.
   Projectiles: Objects that are launched or
thrown into the air and are subject to
gravity.
Projectile Motion
   The difference is that one bullet has
INITIAL VELOCITY.
   Projectiles: Objects that are launched or
thrown into the air and are subject to
gravity.
   Projectile Motion: Free fall with an initial
horizontal motion.
Summary of Equations
Projectiles – Horizontal Launch
Vertical          Horizontal
y = ½ gt2         x = vxt

vy,f = gt         vx = constant

vy,f2 = 2gy
Example problem
   A movie director is shooting a scene
that involves dumping a stunt dummy
out of an airplane into a pool. The plane
is 10m above the ground traveling at
22.5m/s in the positive x direction.
Where in the path should the dummy
be dropped in order to land in the pool?
Example cont.
Given:

22.5 m/s      vx = 22.5 m/s

y = -10 m
10 m
g =-9.8 m/s2

Find x
1. Get time t from y = 1/2gt2
t = √2y/g) = √(2(-10m)/-9.8m/s2)
= 1.43 sec
2. Find x for 1.43 sec ->x = vxt
=22.5m/s *1.43s
= 32.2 m
So drop the dummy 32m before the pool.
Instantaneous Velocity
   To find the final velocity of the dummy
just before it hits the pool, you take the
vector sum of the x and y components
of the velocity.
   vx is always a constant 22.5m/s
   vy,f = gt = -9.8m/s2(1.43 sec) = 14m/s
   Use Pythagorean Theorem and tan-1 to
find the vector sum