Momentum

• Momentum

  The product of an object's mass and velocity.
• Conservation of Momentum

  The principle that states the total momentum of a closed system remains constant before and after a collision.
• Collision

  An event where two or more objects interact and exchange momentum.
• External Force

  A force acting on an object from outside the system, causing a change in momentum.
• How is an airbag useful?

  Reduces the risk of head injuries by increasing the time taken to stop, thereby decreasing the rate of change in momentum and reducing the force.
• Momentum

  Mass x Velocity
• The unit used for momentum is kg m/s (kilogram metres per second)
• In a closed system, the total momentum before a collision is equal to the total momentum afterwards
• Equation linking change in momentum, force and time

  1. Force x Time = Change in Momentum

  2. F Δt = mΔv
• Force experienced in a collision


  The rate of change of momentum
• If an object's change of momentum is fixed

  The only way to reduce the force that the object experiences is to increase the length of time over which the change of momentum occurs
• A seatbelt improves a passenger's safety during a collision by: