Momentum (HIGHER)

• What is momentum?

  The product of an object's mass and velocity.
• What will happen if Object A collides with Object B while it’s stationary?

  Object A transfers its kinetic energy to object B (assuming the objects are of the same mass.)
• What is the equation for Momentum?

  p = mv
• What is momentum measured in?

  Kilogram meters per second (kg m/s)
• What is mass measured in?

  kilograms (Kg)
• What is velocity measured in?

  Meters per second (m/s)
• A lorry has a mass of 7,500 kg. It travels south at a speed of 25 m/s. Calculate the momentum of the lorry.

  p = mv

  p = 7500 x 25

  p = 187500 Kgm/s
• An ice skater has a mass of 60 kg and travels at a speed of 15 m/s. Calculate the momentum of the skater.

  p = mv

  p = 60 x 15

  p = 900 Kgm/s
• What is conservation of momentum?

  The principle that the total momentum of a closed system remains constant if no external forces act on it.
• In a closed system:

  Total momentum before an event = total momentum after the event
• What is a ‘closed system?’

  A ‘closed system’ is something that is not affected by external forces. This is called the principle of conservation of momentum. Momentum is conserved in collisions and explosions.
• Give an example of conservation of momentum

  Conservation of momentum explains why a gun or cannon recoils backwards when it is fired. When a cannon is fired, the cannon ball gains forward momentum and the cannon gains backward momentum. Before the cannon is fired (the ‘event’), the total momentum is zero. This is because neither object is moving. The total momentum of the cannon and the cannon ball after being fired is also zero, with the cannon and cannon ball moving in opposite directions.