Ive been working on my physics homework for the last couple hours and Ive got all but one problem. Im not even sure really where to start. I know its a conservation of momentum problem, but its got both translational and rotational momentum in it. If anyone knows how to relate the 2, I'd be eternally grateful.



Thnx

Andy



Heres the problem:

 

Sorry I don't speak greek...

 

Its not greek, its geek.

 

icould solve it but i dont want to bore myself with old skool physics sowwy

 

All Im asking for is one equation relating angular momentum to translational momentum. If, that is, you even know it.

 

okay, translational momentum is p = mv. figure out how much momentum is transferred because of the angle. input in the angular momentum formula, L = Iw (w = v/r) the w symbol is the curved w, i believe it's called omega. inertia for a rod is 1/12 (mass)(length)^2 so we get angular momentum = (Mass x length^2 x velocity) / (12 x radius)



i hope this helps.

 

sounds greek to me :P



Sean

 

The way Im reading that, it will give me the angular velocity of the stick if all of the impulse from the puck goes into angular momentum. This doesnt work as the stick has angular and translational momentum. I can use that to get the tangential velocity at the point of impact, but how do I find out how much of the velocity goes into rotation and how much goes into translation?



I have been able to solve for the angular velocity gained by the stick by using L=R X(cross) V. Using this I can find the 'angular' momentum of the puck before and after the collision as related to the center of mass of the stick. However using this I can only solve for angular velocity of the stick. If I try to solve the equation for the velocity vector of the center of mass, then 'R' is zero and I have no velocity. I have tried to put these answers in (the problems are online) but the damn thing just keeps telling me Im wrong.

 

hmmm, i thought it was attached at the bottom. i never figured out how to do these questions. sorry man.