Solving for Angular and Linear Velocities in a Two Car Collision

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Discussion Overview

The discussion revolves around solving for the angular and linear velocities of two cars involved in a collision. Participants explore various equations and relationships related to the velocities of the centers of mass and angular velocities, considering factors such as the coefficient of restitution and moments of inertia. The scope includes theoretical and mathematical reasoning related to collision dynamics.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant outlines the known variables and equations needed to find the velocities and angular velocities after the collision.
  • Another suggests relating angular velocity to linear velocity through acceleration vectors, emphasizing the need to consider rotations about the center of mass.
  • A participant raises concerns about the absence of a time period for the collision, questioning the use of acceleration in the analysis.
  • Discussion includes the idea that the net acceleration of points in the system can be derived from the cross product of angular velocity and velocity components.
  • Some participants discuss the implications of taking the point of impact as the instantaneous center of zero velocity, noting that both the center of mass and impact points have non-zero velocities.
  • Several participants propose using relative velocity equations and the parallel axis theorem to derive unknowns related to the collision.
  • One participant expresses confusion about the angular impulse equation and its setup, indicating uncertainty about the correctness of their approach.
  • Another participant mentions the need to treat each body separately and suggests breaking the collision into parts to analyze energy changes.

Areas of Agreement / Disagreement

Participants express differing views on the application of various equations and principles, particularly regarding the treatment of angular momentum and energy conservation in the context of the collision. The discussion remains unresolved, with multiple competing approaches and interpretations present.

Contextual Notes

Participants acknowledge limitations in their understanding and the complexity of the problem, noting that the textbook examples do not cover scenarios as intricate as the current discussion.

  • #31
I think you have to treat each body separately. you have a net loss of energy since your coefficient of restitution is less than 1. You should break up the collision into 3 parts. Find the energy before, the change during, and the energy after the collision.

Check this out, it should be of some assistance. http://www.myphysicslab.com/collision.html

Scroll all the way down near the bottom of the page.
 
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  • #32
I understand that there is energy loss. However, momentum is conserved I thought... which is why conservation of momentum is applied. If that's the case then I don't understand why you can't apply conservation of angular momentum to point P and treat the cars as an entire system.
 

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