(adsbygoogle = window.adsbygoogle || []).push({}); A 0.45 kg ice puck, moving east with a speed of 3 m/s, has a head-on collision with a 0.9 kg ice puck. Assuming a perfectly elastic collision, what will be the speed and direction of each object?

Alright, so the first time i go through this problem i solve it, no problem. the answer is 1 m/s west and 2 m/s east and thats also the answer in the book. but then i go back and i realize something weird. i set up the momentum equation like normal so that it's

0.45*3 = 0.9v1 + 0.45 v2

and then you can make it

0.45*3 = 0.45*2v1 + 0.45 v2

divide both sides by 0.45

3 = 2v1 + v2

and you get that but the values determined for the speeds dont match up with that. What's going on?

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# Homework Help: Elastic collision speed and time problem

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