1. Jul 12, 2004 #1

   wilmerena

   

   do 2 objects that have the same kinetic energy necessarily have the same momentum? I cant think of a simple example :yuck:

    

   wilmerena, Jul 12, 2004
2. 
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3. Jul 12, 2004 #2

   AKG

   

   Science Advisor

   Homework Helper

   Consider a 5 kg mass going at 50 m/s, thus having 6.25 kJ of kinetic energy. Now, a mass of 125 kg going 10 m/s also has 6.25 kJ of kinetic energy. However, the first object has a momentum of 250 kg*m/s, and the second has 1250 kg*m/s of momentum.

    

   AKG, Jul 12, 2004
4. Jul 12, 2004 #3

   wilmerena

   

   thanks so much =o) !!

    

   wilmerena, Jul 12, 2004
5. Jul 13, 2004 #4

   wilmerena

   

   what if they both have 0 momentum, so does it follow that the kinetic energy of the system doesnt have to be zero as well? or does it?

    

   wilmerena, Jul 13, 2004
6. Jul 13, 2004 #5

   Doc Al

   

   Staff: Mentor

   Think about it. For a simple object:
   [tex] KE = 1/2 mv^2[/tex]
   [tex] momentum = mv[/tex]
   The only way an object can have zero momentum is if its speed (v) is what? Then what is its KE?

    

   Doc Al, Jul 13, 2004
7. Jul 13, 2004 #6

   wilmerena

   

   thanks again, i think i just spaced out on that one ;oP

    

   wilmerena, Jul 13, 2004

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