Chap7 - 5. Strategy Add the momenta of the three particles....

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5. Strategy Add the momenta of the three particles. Solution Find the total momentum of the system. [] tot 1 2 3 1 1 2 2 3 3 1 1 2 2 3 3 11 2 2 33 north south north ( ) north (3.0 kg)(3.0 m s) (4.0 kg)(5.0 m s) (7.0 kg)(2.0 m s) north 3 kg m s north mm m m v m v m v mv m v =++= + + = + + =−+ = + =⋅ pp p p v v v rr r rrrr 7. Strategy The initial momentum is toward the wall and the final momentum is away from the wall. Solution Find the change in momentum. fi f i f i ( ) (5.0 kg)( 2.0 m s 2.0 m s) 20 kg m s, so 20 kg m s in the -direction . pp p m v m v v x Δ= − = = − = =− Δ= p r 14. Strategy Use the impulse-momentum theorem. Solution (a) Compute the changes in momenta for each direction. north east av east east 0 and . F t m v m v Δ=Δ = Δ = Δ = Find the magnitude and direction of f . v r 2 2 av 22 2 2 f north east north (15 N)(4.0 s) (15 m s) 25 3.0 kg Ft vv v v m Δ ⎡⎤ ⎛⎞ =+ = + = ⎜⎟ ⎢⎥ ⎝⎠ ⎣⎦ 15 N N 15 m/s north f east 15 m s tan tan 37 north of east, so 25 m s at 37 north of east .
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This note was uploaded on 03/01/2009 for the course PHY 2130 taught by Professor Rehse during the Winter '08 term at Wayne State University.

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Chap7 - 5. Strategy Add the momenta of the three particles....

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