PHY221 Ch13: Collisions, Impulse and Ref. Frames
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Transcript of PHY221 Ch13: Collisions, Impulse and Ref. Frames
PHY221 Ch13: Collisions, Impulse and Ref. Frames
1. Recall main points: A. Speed relation for elastic collisions. Helps solve some problems:
B. Definition of impulse and average force on one of the objects during any collision:
C. General expression for Kinetic energy:
2. Discussion and examples• Nothing special
PHY221 Ch13: Collisions, Impulse and Ref. Frames1.
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Proof: relative speed remains the same before /after collision:
PHY221 Ch13: Collisions, Impulse and Ref. Frames1.
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Impulse definition and expression in terms of average force on object during collision
PHY221 Ch13: Collisions, Impulse and Ref. Frames1.
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Proof: Kinetic Energy expression:(F=lab for instance) /
2/ /
12 CM FSYS F SYS CMK K MV
Prelim #1: * 0i imv
Prelim #2 for any mass mi : */ / / /i F i CM CM F i CM Fv v v v v
Now we compute 2/ / / /
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2( )SYS F i i F i i F i FK mv m v v
PHY221 Ch13: Collisions, Impulse and Ref. FramesEX
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