Projectile Motion #1
Lesson 7
Announcements
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HW #6 due today
HW #7 due tomorrow
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Lunch Bunch meets this week
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Lesson 7 – Projectile Motion #1
AP Physics B Standard:
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I. A. 2. c) Students should understand the motion of projectiles
in a uniform gravitational field, so they can:
(1) Write down expressions for the horizontal and vertical
components of velocity and position as functions of time, and
sketch or identify graphs of these components.
(2) Use these expressions in analyzing the motion of a projectile
that is projected with an arbitrary initial velocity.
Objectives:
Students will be able to
• predict the trajectory of a horizontally-launched
projectile.
• mathematically model projectile motion using principles
of physics
Monkey and Banana
•
http://www.physicsclassroom.com/mmedia/vectors/mzi.cfm
• A cannon launches a banana to a hungry
monkey hanging from a tree branch.
• The monkey, excited, lets go of the branch at
the moment of launch.
– Where should the cannon aim?
Angry Birds
• http://chrome.angrybirds.com/
• Level 1-2.
Why can’t I just aim straight at the pigs?
• Use LoggerPro to determine ‘g’ in
AngryBirdWorld.
• Why would ‘g’ be different there?
More Angry Birds physics:
•
http://fnoschese.wordpress.com/2011/06/16/angry-birds-in-the-physics-classroom/
•
http://www.wired.com/wiredscience/2010/10/physics-of-angrybirds/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+wired/index+%28Wired:+
Index+3+%28Top+Stories+2%29%29
Independence of Motion in
Projectiles
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For projectiles fired horizontally or
at an angle:
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Horizontal velocity is constant.
Vertical velocity is accelerated by
gravity.
For projectiles in Physics B, air
resistance will be ignored.
4 types of projectiles
•
Sample Problem: The Zambezi River flows over Victoria Falls in Africa.
The falls are approximately 108 m high. If the river is flowing
horizontally at 3.6 m/s just before going over the falls, what is the
speed of the water when it hits the bottom? Assume the water is in
freefall as it drops.
Sample problem: An astronaut on the planet Zircon tosses a rock
horizontally with a speed of 6.75 m/s. The rock falls a distance of 1.20
m and lands a horizontal distance of 8.95 m from the astronaut. What
is the acceleration due to gravity on Zircon?