4.3.A—Describe the behavior of a system using conservation of linear momentum

Describe the behavior of a system using conservation of linear momentum.

• A collection of objects with individual momenta can be described as one system with one center-of-mass velocity.
  • i. For a collection of objects, the velocity of a system’s center of mass can be calculated using the equation
  • ii. The velocity of a system’s center of mass is constant in the absence of a net external force.
• The total momentum of a system is the sum of the momenta of the system’s constituent parts.
• In the absence of net external forces, any change to the momentum of an object within a system must be balanced by an equivalent and opposite change of momentum elsewhere within the system. Any change to the momentum of a system is due to a transfer of momentum between the system and its surroundings.
  • i. The impulse exerted by one object on a second object is equal and opposite to the impulse exerted by the second object on the first. This is a direct result of Newton’s third law. TOPIC 4.3 Conservation of Linear Momentum
  • ii. A system may be selected so that the total momentum of that system is constant.
  • iii. If the total momentum of a system changes, that change will be equivalent to the impulse exerted on the system. Relevant equation:
• Correct application of conservation of momentum can be used to determine the velocity of a system immediately before and immediately after collisions or explosions.