# Lecture7

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Unformatted text preview: g Two ­dimensional collisions For 2D collisions, we have the same vector equa6on for the conserva6on of linear momentum: ( p1 + p2 )before = ( p1 + p2 )after or, p1i + p2 i = p1 f + p2 f However, we have two equa1ons (instead of just one of 1D case), the x and y components of this equa6on. For elas6c collisions, we have an addi1onal equa1on, the equa6on for kine6c energy conserva6on: ( K1 + K 2 )before = ( K1 + K 2 )after or, K1i + K 2 i = K1 f + K 2 f Example What is the velocity of the target ball (black, at rest ini;ally) aWer the collision? Take m1 = m2 200g. Is this collision elas;c? Linear momentum conserva;on: x ­component: m1v1i = m1v1 f cosθ1 + m2 v2 f cosθ 2 y ­component: 0 = − m1v1 f sin θ1 + m2 v2 f sin θ 2 m Plugging in v1i = 4 m / s, v2 = 2 m / s, v 1 f = v ,θ 2 = 45 o ,θ 1 = θ , 2 = m2 = 0.2 kg f in these three equa;on we get v cosθ = 2.59 v sin θ = 1.41 Solving these...
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## This note was uploaded on 11/16/2010 for the course PHY 2170 taught by Professor Blank during the Spring '08 term at Wayne State University.

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