PhysicsLAB CP Workbook
Momentum Systems and Conservation

When the compressed spring is released, blocks A and B will slide apart. There are 3 systems to consider here, indicated by the closed dashed lines below: System A, System B, and System A+B. Ignore the vertical forces of gravity and the support force of the table.

Does an external force act on System A?
 
Will the momentum of System A change?
 
Does an external force act on System B?
 
Will the momentum of System B change?
 
Does an external force act on System A+B?
 
Will the momentum of System A+B change?
 
Billiard ball A collides with billiard ball B at rest. Show your partner where you would place a closed dashed line to isolate each system. Then discuss what, if any, external force vectors act on each system.

The image “http://online.cctt.org/physicslab/content/cpworkbook/page_19/circlesystemA.gif” cannot be displayed, because it contains errors.     The image “http://online.cctt.org/physicslab/content/cpworkbook/page_19/circlesystemB.gif” cannot be displayed, because it contains errors.     The image “http://online.cctt.org/physicslab/content/cpworkbook/page_19/circlesystemAB.gif” cannot be displayed, because it contains errors.


Upon collision, the momentum of System A.
 
Upon collision, the momentum of System B.
 
Upon collision, the momentum of System A+B.
 
A girl jumps upward. Show your partner where you would place a closed dashed line on the sketch given below to indicate the system of the "girl." Then discuss what, if any, external force vectors act on the system of the "girl."

Is there an external force acting on her?
 
Is the girl's momentum conserved?
 

Now show your partner where you would place a closed dashed line on the sketch below to indicate the system of the "girl + earth."

Is there an external force due to the interaction between the girl and the earth that acts on the system?
 
Is the momentum of the system conserved?
 


A block strikes a blob of jelly. Show your partner where you would place closed dashed lines to isolate three systems. Then discuss what, if any, external force vectors act on each system.

         

In which system is momentum conserved?
 
A truck crashes into a wall. Show your partner where you would place closed dashed lines to isolate three systems. Then discuss what, if any, external force vectors act on each system.
 
         

In which system is momentum conserved?
 




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