Energy and Momentum Conservation in Inelastic Car Collisions

AI Thread Summary
In an inelastic collision involving two cars of mass m, one traveling north at speed 2v and the other at speed v at an angle phi south of east, the cars stick together post-collision. The final speed v_final and angle theta of the combined mass must be determined using conservation of momentum, as energy conservation does not apply due to the inelastic nature of the collision. Participants suggest breaking down the momentum conservation into x and y components to solve for the unknowns. One user has attempted to calculate v_final but is unsure of the correctness of their formula. The discussion emphasizes the importance of showing work to identify errors in the calculations.
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Two cars, both of mass m, collide and stick together. Prior to the collision, one car had been traveling north at speed 2v, while the second was traveling at speed v at an angle phi south of east (as indicated in the figure). After the collision, the two-car system travels at speed v_final at an angle theta east of north.
 

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Conservation of momentum, remember velocity is a vector quantity.

Show your work so we can determine where you need help.
 
can anyone help me with the above problem? I've been trying to work it out but i can't find the answer to vfinal... or theta
 
Like civil_dude said, show your work so we know where you went wrong.

Either use the velocities as vectors or break the conservation of momentum into its x and y components.
 
i got the other homework problems but i don't think I'm even close for this one. the answer that i have so far for vfinal i have sqrt( (v*cos(phi))^2 + (2v - vsin(phi)^2)

but that doesn't work or feel right either. and i can't even begin to find theta
 
Are you using energy conservation? The collision is inelastic. Use conservation of momentum.
 
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