Physics 2211: Lecture 21 Notes

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Physics 2211 Lecture 20
2D Kinematics Projectile Motion
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Typical 2D Problem What is the Trajectory of the
Bouncing Ball?
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Fundamental Quantities
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2-D Kinematics
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The Big Idea
Treat each coordinate direction independently.
Use vector addition to get the complete motion
in 2D.
Constant Acceleration
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t0
x and y motion are independent
t1
These two balls hit the ground at the same time.
t2
Does that disagree with your intuition?
t3
t4
If so, amend your intuition!
t5
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Projectile Motion
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Galileo (1638)
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Trajectory of projectile motion is a parabola
negative curvature
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The Monkey (Coconut) Shot
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Bullet
h
d
Monkey
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For the 2D trajectory shown to the right, if the
speed is a constant along the straight segments,
the external force
y
x

• Is the same in every region
• Is different in every region
• Is the same in some regions
• Never changes sign

Correct answer is 3
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Recap
2D Kinematics Projectile Motion
Next Lecture
More Projectiles Relative Motion