projectile motion and trajectory
DESCRIPTION
Projectile Motion and Trajectory. You’ve Been Watching it for Years. Projectiles are objects moving through space or the air with their own inertia and acted on by gravity. Projectiles have a horizontal or X motion. Gravity does not act in the X direction. - PowerPoint PPT PresentationTRANSCRIPT
Projectile Motion and Trajectory
You’ve Been Watching it for Years
Projectiles are objects moving through space or the air with their own inertia and
acted on by gravity.
Projectiles have a horizontal or X motion.
Gravity does not act in the X direction.
If there is no friction the x motion is at constant
velocity.
Projectiles have a vertical or y motion.
Velocity in the y direction will accelerate because of
gravity.
Because acceleration
due to gravity is constant a projectile and
free-falling object will hit the ground at
the same time!
The projectile will travel in a parabola, the combination of the
x and y motion.
Upwardly Launched Projectiles
In the absence of gravity the projectile flies in a straight line!
Gravity pulls the projectile down as if it has been free-falling from
each point!
If there is no air resistance the horizontal or x velocity
stays constant!
Notice the vertical or y velocity decreases as the projectile goes upwards!
Yet the vertical or y velocity increases as the projectile
goes downwards!
Why?
The vertical speed of the cannonball lost going upwards……
50 m/s
30 m/s
10 m/s 10
m/s30 m/s
50 m/s
Equals the vertical speed of the
cannonball gained going
downwards……
50 m/s
30 m/s
10 m/s 10
m/s30 m/s
50 m/s
What is the vertical speed of the
cannonball at the top of the parabola?
0 m/s
What about air resistance?
No air resistance
With air resistance
Air resistance causes the
trajectory to be less than the ideal path!
Force of LaunchA projectile launched with more force will go further than one launched with less force if all other factors are the
same….
Does Angle of Launch Matter?
Yes!
45° gives maximum distance or range! (x and y are equal)
Any two angles which add up to 90° gives the same distance or
range but not the same trajectory!
75° + 15° = 90°
60° + 30° = 90°
Is an airplane a projectile?
No! It is not moving on its own inertia but by constant thrust
from the jet engines!
With the right amount of force a projectile will fall at the same rate
as the Earth’s surface curves!
Satellites need to have a velocity of 8 km/s to stay in
orbit.
Satellites do not escape the Earth’s gravity but orbit above
the atmosphere. Why?
Once they escape the atmosphere there is no friction
so velocity is constant!
The End