Post on 15-Nov-2014
description
Projectile Motion
What is a projectile?• Any object that moves through the air or
space with an initial velocity and makes a parabolic path is called a projectile
First…
• Let’s think about objects that move in a straight line…
Horizontal Motion
• If there were no gravity, an object moving horizontally (in the x-direction) would continue to move _________________in a straight line
Vertical Motion
• If an object is dropped vertically (in the y-direction), then _______ causes it to
• ___________ downwards
gravity
accelerate
Projectile Motion
• Projectile motion is a ________________!
• In the x-direction, it continues to move at a __________ speed, but in the y-direction, it ___________downwards because of gravity!
combination
constantaccelerate
Take-Home Message!!!
For a projectile: THE X-VELOCITY IS _________________ OF THE Y-VELOCITY!!!
The speed in the x-direction doesn’t care what the speed in the y-direction is!
INDEPENDENT
Why?
• Remember that _____________is only pulling in one direction (__________!) and nothing is pulling ________________
• If there were no gravity, a projectile would go __________forever:
gravitydown right or left
straight
Velocity Vectors
• Remember that velocity has a ____________, so it can be represented using ____________!
• We can break down the velocity into separate x- and y- components:
directionvectors
Velocity Vectors
• Let’s examine the x and y velocity vectors for a projectile:
• Its x-velocity stays __________and its y-velocity _____________.
constantincreases
Y-VelocityJust like in free-fall:
Velocity in the y-direction ___________on the way up, and ____________on the way down
At the top of the path, the y-velocity is always ______ Velocity on the way up ________velocity on the way down when
you reach the same _________
decreasesincreases
zeroequals
height
*Checkpoint Question 1*
• If you were walking at a constant velocity with a baseball and threw it up into the air while you were walking, would it fall– A. in front of you– B. behind you– C. right back into your hands?
• Why??
Answer!
• Its y-velocity is different than yours, but its x-velocity stays the same as you. It should land back into your hands!
**Checkpoint Question 2**
• An airplane is carrying a bomb and traveling with a velocity of 1,100 mph east. If it releases its bomb and continues at that velocity, will the bomb land:– A. Directly underneath the plane– B. Behind the plane– C. Ahead of the plane
Answer!
• If they’re going at the same x-velocity, it will land directly beneath the plane!
***Checkpoint Question 3***
• Suppose two balls released from the same height: one is dropped from rest, and the other is thrown horizontally. Which will hit the ground first? Why?
• They will hit at the same time, because they are both being pulled by gravity at the same rate! Only one will have a greater x-range.
X-Range and Max Vertical Height
• Your x- distance is called your __________and your y-distance is called your __________.
• Your range and height depend on:– The _______ that the projectile is launched at and– The __________it is launched at
rangeheight
anglevelocity
Angle
• Increasing your angle increases your range until you reach 45°.
• 45° to 90°, increasing your angle decreases your range.
Initial Velocity
• The greater the initial velocity of a projectile, the ____________it will go:farther
The trajectory of an object depends on how fast it is moving horizontally and how long gravity acts on it
for.
Earth
The trajectory of an object depends on how fast it is moving horizontally and how long gravity acts on it for.
Earth
Small horizontal velocity
The trajectory of an object depends on how fast it is moving horizontally and how
long gravity acts on it for.
Earth
Medium horizontal velocity
The trajectory of an object depends on how fast it is moving horizontally and how long gravity acts on it
for.
Earth
Fast horizontal velocity
Projectile Motion
A projectile is always falling.The faster it moves horizontally, the
farther away it will be when it hits the ground.
SlowMedium
Fast