momentum

• What is the turning effect of a force called?

  Moment
• How is moment calculated?

  Moment = force × perpendicular distance
• What are the units for moment?

  Newton metre (Nm)
• What happens when clockwise and anticlockwise moments are compared?

  • Clockwise moment > Anticlockwise moment: turns clockwise
  • Anticlockwise moment > Clockwise moment: turns anticlockwise
  • Clockwise moment = Anticlockwise moment: stays balanced
• What is the Principle of Moments?

  Total clockwise moment = total anticlockwise moment
• How does weight affect the see-saw balance between Garfield and Odie?

  Odie must sit farther from the pivot
• How is weight calculated?

  Weight = mass × 10
• What happens to upward forces when a person moves on a bridge?

  More weight shifts to the left support
• What is the centre of gravity?

  The point where an object balances
• How is the centre of mass positioned in regular objects?

  At the very centre of the object
• How does the stability of an object change with its centre of gravity and base length?

  • Lowering the centre of gravity increases stability
  • Increasing the base length increases stability
• What happens when the line of action of weight lies outside the base of an object?

  The object will topple
• Why are racing cars stable?

  They have a low centre of gravity and wide base
• What is momentum?

  The product of mass and velocity
• Why is momentum important in physics?

  It helps explain collisions and explosions
• How is momentum calculated?

  Momentum = mass × velocity
• What are the units for momentum?

  Kilogram metres per second (kg m/s)
• What does it mean that momentum is conserved?

  Momentum before = momentum after an event
• What are the types of collisions?

  1. One vehicle stationary, other hits
  2. Both vehicles same direction
  3. Two vehicles opposite directions
• In a collision, what happens to the momentum of two gliders on an air track?

  They stick together and share momentum
• What is the total momentum of glider A (0.25 kg, 7 m/s) and glider B (stationary)?

  1.75 kg m/s
• How do you find the velocity of combined gliders after a collision?

  Use total momentum and total mass
• What happens to momentum when a cannon fires?

  The cannon recoils with equal negative momentum
• How does force relate to momentum?

  Force = change in momentum / time
• Why is wearing a seatbelt important in a car crash?

  It prevents injuries by reducing force
• How can the time for change in momentum be increased to reduce injuries?

  • Crumple zones in cars
  • Airbags
  • Soft padding in helmets
  • Crash mats
• What is the effect of increasing the time for change in momentum?

  Reduces the force exerted on occupants
• How do crash helmets protect the head?

  They have soft padding to absorb impact
• What is the purpose of rubber floors in play parks?

  To absorb impact and reduce injuries