Ok, I have tried to work this out for about an hour now and I haven't gotten very far. In the question there are two equal masses. One of them is moving at a given velocity and the other is not moving at all. After the collision one disk goes off on a given angle while the other disk goes off on an angle perpendicular to that of the second disk. The question wants me to solve for the final velocities.(adsbygoogle = window.adsbygoogle || []).push({});

So this is whats given:

Mass one Mass two

Initial velocity = 0 Initial velocity = vi1

Final velocity = ? Final velocity = ?

Angle = 90-A2 (Not sure if thats right) Angle = A2

Mass = Mass two Mass = Mass one

Oh ya and the collision is perfectly elastic. So I think I am supposed to have like 4 unknowns and then I am suposed to have 4 different equations. But the only equation I am aware of right now is

vi1 = v1f + v2f

This can be split up to two other equations like so:

vi1x = v1fx + v2fx

vi1y = v1fy + v2fy

Ok, so I think thats right so far, then what I did was I made four other equations like so:

v1fy = v1fy(sinA2-90)

v1fx = v1fx(cosA2-90)

v2fy = v2fy(sinA2)

v2fx = v2fx(CosA2)

Now I plugged those into the original two equations like so:

v1ix = v1fx(cosA2-90) + v2fx(cosA2)

v1iy = v1fy(sinA2-90) + v2fy(sinA2)

Now this is where I am stuck. I am not sure if I am on the right track right now but I hit a dead end. I have too many unknowns and not enough equations. Either the answer is really easy and I just can't see it, or I messed up somewhere, or theres another equation I am supposed to use. But right now I am really stuck and would appreciate any help given.

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# Homework Help: 2D Collision problem, need help please

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