AP physics Unit 5 Momentum

• Conservation of mass: in a closed system, the total mass of the system remains constant
• the more momentum an object has the harder it is to stop
• conservation of momentum: the total momentum of an isolated system of bodies remains constant
• System: set of objects which interact with each other
• Isolated system: the only forces are those between objects of the system
• Impulse: Newton's second law states that a force is required to change the momentum of an object
• momentum = mass x velocity
• impulse = Force x time
• Elastic collisions: objects perfectly bounce off one another,

  • momentum is conserved
  • all kinetic energy is conserved
  • can use equation $Vai-Vbi=$$Vbf-Vaf$
• Inelastic collisions: objects bounce off one another

  • momentum conserved
  • kinetic energy is not conserved
• completely inelastic collision: both objects stick together after the collision

  • after collision they are treated as one object
  • momentum is still conserved
  • kinetic energy is not conserved
• Center of Mass: The point in an object where the weight is concentrated.
• area under force and time graph is impulse
• Center of mass equation: $Xcm=$$(m1x1+m2x2)/M$