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Unformatted text preview: Lecture 21 Summary
Impulse = change in momentum!
J = p = p f - pi = I Physics131 tf ti F dt Inelastic Collision: Momentum is conserved but not KE
(e.g. trains stick together after collision)
m1v1 I + m 2 v 2 I = ( m1 + m 2 ) v f v2 I = 0 v f = m1v1 I m1 + m 2 Collisions in one dimension In one dimension, the impulse is just the area under the F Vs t curve. Ballistic Pendulum: used to measure the speed of a bullet. a) During collision net external force is zero, mom is conserved b) Collision is 1D and inelastic m+M 2 gh c) After collision ME of bullet/block/earth is conserved v = m Elastic Collision: momentum & KE conserved
v1 f = m1 - m2 v1I m1 + m2 v2 f = v1I + v1 f = 2m1 v <0 if m <m v1I v1f =0 if m1=m2 1f 1 2 m1 + m2
v1f >0 if m1>m2
1 Phys131 Richard Kass ...
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- Spring '08