(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Hockey puck B rests on a smooth ice surface and is struck by a second puck A, which has the same mass. Puck A is initially traveling at 15.2 m/s and is deflected 30.0^\circ from its initial direction. The pucks are made of superball-like material, so you may assume that the collision is perfectly elastic.

Find the final speed of the puck A after the collision

2. Relevant equations

conservation of momentum for one object at rest (1)

mv_{ai}= mv_{af}+ mv_{bf}

conservation of kinetic energy (2)

1/2mv_{ai}= 1/2mv_{af}+ 1/2mv_{bf}

3. The attempt at a solution

I have tried this about 10 times and cannot get it right :(

i solved equation 1 for the x and y components of the velocity final for puck b

v_{bxf}= v_{axi}- v_{axf}

v_{byf}= -v_{ayf}

so

v_{bf}= sqrt [(v_{axi}- v_{axf})^{2}+ (-v_{ayf})^{2}]

v_{bf}= sqrt [v_{axi}^{2}- 2v_{axf}+ v_{axf}^{2}+ v_{ayf}^{2}]

then i plugged this into 1/2mv_{ai}= 1/2mv_{af}+ 1/2mv_{bf}for v_bf

i would show all my steps of reducing but it would take forever.

i end up getting v_{fa}= cos(30) = .866 but this is wrong

am i right up to this point of what i have done?

any help would be great. Thank you

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# Homework Help: Elastic collision of hockey puck

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