Help Collisions between astroids?

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Homework Help Overview

The discussion revolves around a physics problem involving collisions between two asteroids, focusing on their masses, velocities, and the resulting changes in kinetic energy. The original poster presents a scenario where a 6 kg asteroid collides with an 18 kg asteroid, seeking to determine the final velocity of the second asteroid and the change in internal energy post-collision.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply a formula related to momentum but questions the validity of their assumptions about the angle of collision. They also seek clarification on how to calculate the change in internal energy.
  • Some participants suggest using conservation-of-momentum equations for each spatial direction to approach the problem.
  • There is a discussion about the method for calculating the change in internal energy, with the original poster considering the difference in kinetic energy before and after the collision.

Discussion Status

The discussion is active, with participants providing guidance on using conservation laws and confirming the approach to calculating kinetic energy. There is an ongoing exploration of the assumptions made regarding the collision dynamics.

Contextual Notes

The original poster expresses uncertainty about the angle of collision and the implications of unequal masses on their calculations. There is a focus on ensuring the correct application of physics principles without providing direct solutions.

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help! Collisions between asteroids?

Homework Statement



In outer space a rock with mass 6 kg, and velocity < 4200, -3100, 3000 > m/s, struck a rock with mass 18 kg and velocity < 250, -280, 360 > m/s. After the collision, the 6 kg rock's velocity is < 3700, -2500, 3500 > m/s.

What is the final velocity of the 18 kg rock? "need the x, y, and z component"

What is the change in the internal energy of the rocks? "in J"



The Attempt at a Solution


i used
P1^2 = P3^2 + P4^2 + 2P3P4cos A
where A is the angle between the particles. I did not know what A was so i assumed that it was 90 degrees like it would be in an elastic collision with identical masses, but that is a bad assumption becasue the masses are not equal.
so now I am stuck. any help or a formula would be great
thanks all!
 
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Try writing conservation-of-momentum equations, one for each direction (x, y, and z).
 


ok i just did not divide by the mass at the end. i put in P instead of V

now how will i find the change in internal energy?
would i just find KE of both masses in the inital state minus the KE of both masses in the final state?
 


fball558 said:
now how will i find the change in internal energy?
would i just find KE of both masses in the inital state minus the KE of both masses in the final state?

Yes.
 

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