Conservation Of Linear Momentum and Types of Collisions

Conservation of Linear Momentum

• If the mass and velocity remain the same, the momentum value will be constant

• The momentum of an object remains the same if it is left alone

• Internal Forces: forces that particles of a system exert on one another

• External Forces: forces applied on any part of the system by objects outside the system

• Isolated Systems: systems with no external forces

• Law of Conservation of Momentum

  • “In a closed and isolated system, the total momentum of the objects before and after the collision are equal.”

• Formula:

  • m^1u^1+m^2u^2=m^1u^1+m^2v^2

Types of Collisions

• Perfectly Inelastic Collision

  • Objects stick together after collision, moving as a single body

  • Kinetic energy is not conserved

  • Momentum is conserved

  • E.g., a car crash where cars lock together

• Inelastic Collision

  • Objects do not stick together, but some kinetic energy is lost

  • Some kinetic energy is conserved, some is lost

  • Momentum is conserved

  • E.g., A hockey puck hitting another puck and bouncing off

• Elastic Collision

  • Objects bounce off each other

  • Kinetic energy is conserved

  • Momentum is conserved

  • E.g., collisions of ideal gas molecules in a container