Physics 2211: Lecture 28

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Physics 2211 Lecture 28
Elastic Collisions
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Types of Collisions
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ALL collisions obey the law of conservation of
momentum
An ELASTIC collision also obeys the law of
conservation of energy
For contact-type collisions, this amounts to
conservation of KE
An INELASTIC collision conserves momentum but not
KE.
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Billiards Collisions in Two Dimensions
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Limits!
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Application do try this at home!
M gt gt m
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m
M
Change to frame of reference where M is at rest
Change back to original frame
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Application Newtons cradle
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This collision conserves

• momentum but not energy
• energy but not momentum
• both momentum and energy
• neither momentum nor energy
• not enough information given to decide

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Recap
Elastic Collisions
Next Lecture
Energy Diagrams