Linear Momentum in Collisions

Goal: To investigate the Law of Conservation of Linear Momentum in collisions

• Theory
  
• Preliminary Settings.
  • Open the simulation Collision Lab.
  • From the menu on the right, select: Show Values
  • In the yellow window below, click on "More Data"


• Activity 1: Elastic Collisions in one dimension. Ball 2 is initially at rest.
  • On the menu to the right, slide the indicator all the way to the right for a perfectly elastic collision.
  • For the given masses and initial speeds of the two balls, determine the velocity and momentum after the collision.
    
    

    Ball	Mass (kg)	Before the Collision		After the Collision
    		V (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
    1
    2

    
    

    Ball	Mass (kg)	Before the Collision		After the Collision
    		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
    1
    2

    
    

    Ball	Mass (kg)	Before the Collision		After the Collision
    		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
    1
    2

    Question: Is the momentum conserved?   

    Question: Is the energy conserved?    
  
  
• Activity 2: Elastic Collisions in one dimension. Balls 1 and 2 initially moving in the same direction.
  • Ball 1 and Ball 2 initially moving in the same direction
  
  

  Ball	Mass (kg)	Before the Collision		After the Collision
  		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
  1
  2

  
  

  Ball	Mass (kg)	Before the Collision		After the Collision
  		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
  1
  2

  
  

  Ball	Mass (kg)	Before the Collision		After the Collision
  		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
  1
  2

  Question: Is the momentum conserved?   
  Question: Is the energy conserved?    


• Activity 2: Elastic Collisions in one dimension. Balls 1 and 2 initially moving in the opposite direction.
  
  
  • Note that when Ball 2 moves opposite to Ball 1, its velocity and momentum are negative!
  
  

  Ball	Mass (kg)	Before the Collision		After the Collision
  		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
  1
  2

  
  

  Ball	Mass (kg)	Before the Collision		After the Collision
  		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
  1
  2

  
  

  Ball	Mass (kg)	Before the Collision		After the Collision
  		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
  1
  2

  Question: Is the momentum conserved?   
  Question: Is the energy conserved?    


• Activity 3: Inelastic Collisions
  
  
  • On the menu to the left, slide the indicator all the way to the left to ensure perferctly inelastic collision.
  
  

  Ball	Mass (kg)	Before the Collision		After the Collision
  		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
  1
  2

  
  

  Ball	Mass (kg)	Before the Collision		After the Collision
  		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
  1
  2

  
  

  Ball	Mass (kg)	Before the Collision		After the Collision
  		v (m/s)	Momentum (kg.m/s)	v (m/s)	Momentum (kg.m/s)
  1
  2

  Question: Is the momentum conserved?   
  Question: Is the energy conserved?    

  ---

  Acknowledgements.
  • The Java Applet comes from the PhET Interactive Simulations at the University of Colorado, Boulder.
  • Some activities are based on the "Laboratory Manual, Physics 231 - 232" by Walter Wimbush, Northern Virginia Community College, 2008.
  
  Created: Tue Oct 16 11:32:17 Eastern Daylight Time 2012 Last modified: Tue Oct 16 13:01:59 EDT 2012