Momentum

• Momentum - product of mass and velocity
• Force - rate of change of momentum
• Principle of conservation of linear momentum - when bodies in a closed system interact, the total momentum remains constant, provided no external force acts on the system
• Elastic collisions - total momentum conserved, total kinetic energy conserved

  • the relative speed of the body's approach is equal to the relative speed of their separation
• Inelastic collisions - total momentum is conserved, total kinetic energy is not conserved

  • the relative speed of approach is greater than the relative speed of separation
  • total energy is conserved but kinetic energy may be converted to other forms of energy
• Perfectly inelastic collisions - only momentum is conserved, and the particles stick together after the collision
• Collisions in 2 dimensions

  • change in momentum affecting each body acts along the line of impact
  • law of conservation of momentum applies along the line of impact
  • calculate the y- component and x- component and draw vector triangle
• Momentum and Newton's laws

  • First law - the momentum of an object remains the same unless the object experiences an external force
  • Second law - resultant force is directly proportional to the rate of change of momentum