Energy and Momentum Conservation in Inelastic Car Collisions

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Homework Help Overview

The discussion revolves around an inelastic collision between two cars of equal mass, where one car travels north and the other at an angle south of east. Participants are attempting to determine the final speed and direction of the combined mass post-collision using principles of momentum conservation.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are discussing the application of conservation of momentum, emphasizing the need to treat velocity as a vector. There are inquiries about the correct approach to find the final speed and angle after the collision, with some expressing uncertainty about their current calculations.

Discussion Status

Some participants have provided guidance on showing work to identify errors, suggesting the breakdown of momentum into components. There is acknowledgment of the inelastic nature of the collision, with a focus on momentum rather than energy conservation.

Contextual Notes

Participants are working under the constraints of homework rules, which may limit the information they can share or the methods they can use. There is a noted lack of clarity regarding the calculations for the final speed and angle.

kenau_reveas
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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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