Two billiard balls of equal mass move at right angles and meet at the origin of an xy coordinate system. One is moving upward along the y axis at 3 m/s, and the other is moving to the right along the x axis with speed 4 m/s. After the collision (assumed elastic), the second ball is moving along the positive y axis.(adsbygoogle = window.adsbygoogle || []).push({});

(a) What is the final direction of the first ball?

(b) What are their two speeds?

OK, I use two different for each x and y component:

x-direction: m*4=m*v1'*cos(theta)

y-direction: m*3=m*v2'+m*v1'*sin(theta)

Now I can cancel the masses, but still, I have two equations but 3 unknowns...

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# Homework Help: Billiard ball physics homework

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