A blue puck with a mass of 4.40*10^−2kg , sliding with a speed of 0.250m/s on a frictionless, horizontal air table, makes a perfectly elastic, head-on collision with a red puck with mass x, initially at rest. After the collision, the velocity of the blue puck is 5.00*10^−2m/s in the same direction as its initial velocity.(adsbygoogle = window.adsbygoogle || []).push({});

It asks me for both the mass and the velocity of the red puck.

Well, since neither mass nor velocity is given to me, should I use P=m*v to find the momentum lost and then transfer it to the red puck? Or do I just derive an equation from momentum conservation and plug that into another momentum conservatio equation so I only have one unknown variable, and solve for that? Please advise.

Thanks.

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# Homework Help: How to approach this?

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