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Unformatted text preview: 2 x 1 x y P total = constant (if F total ext = 0): Vector equation (x,y,z components) 1) Total mass conserved 2) If elastic (bounces, slides), total energy conserved : Scalar equation 3) If inelastic (sticks) only P total conserved if F total ext = 0 4) Ch 9: Linear Momentum and Collisions Center of Mass 2 2 1 1 CM r r r m m M + ≡ M = m 1 + m 2 = total mass r CM is the mass weighted position vector or center of mass Why do this? Key idea: The center of mass acts like one particle at r CM acted on by total external force total m m M M dt d P v v v r = + = = 2 2 1 1 CM CM external total total M dt d F a P = = CM Example: Find r CM , a CM if: r 1 = 1 i , m 1 = 1 kg; r 2 = 2 j , m 2 = 2 kg F 1 = 2 N j F 2 = 1N i j i r 2 2 ˆ 1 1 3 CM ⋅ + ⋅ = m 3 1 CM = x m 3 4 CM = y j i a 2 ˆ 1 3 CM + = 2 3 1 xCM m/s = a 2 3 2 yCM m/s = a...
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This note was uploaded on 05/13/2010 for the course PHYSICS 53L taught by Professor Mueller during the Fall '07 term at Duke.
 Fall '07
 Mueller
 Physics, Force, Momentum

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