momentum

• in a closed system what can be said about the momentum before and after a collision

  total momentum before = total momentum afterwards
• what quantity is equal to the force experienced in a collision

  rate of change of momentum
• if an objects change in momentum is fixed, what is the only way to reduce force that the object experiences

  increase the length of time over which the change in momentum occurs
• explain how a seatbelt improves a passenger's safety during a collision

  the force they experience is equal to the rate of the change of momentum

  seatbelts increase the time which the force is applied, reducing the rate of change of momentum and therefore reducing the force experienced