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How To Determine Conservation Of Momentum

According the law of conservation of momentum, the total amount of momentum in a closed system remains constant.


  • TIP: If a moving ball collides with an identical one at rest, the first ball will stop in its tracks and transfer its velocity to the second one.
  • Step 1: Use the law of conservation of momentum to describe the interactions of any number of objects in a closed system.
  • FACT: The French scientist Rene Descartes failed to take into account the idea of direction when he first described the concept of momentum.
  • Step 2: Add the positive and negative changes in momentum of the two objects. Their sum should be zero. According to the Conservation Law, there can be no net change in momentum.
  • Step 3: Measure the changes of momentum of the two objects following contact.
  • Step 4: Multiply the mass and velocity values for each object to determine the momentum of each object.
  • TIP: Velocity, and therefore momentum, has a direction. If an object moving to the left has a positive momentum, then one moving to the right has negative momentum.
  • Step 5: Observe the first object as it comes in contact with the second one.
  • Step 6: Determine the masses and velocities of two objects in an isolated environment.

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