Forces in balance y9

• Centre of mass or centre of gravity


  The point at which an object's mass can be thought of as being concentrated
• Regular objects


  • In the middle
• Low centre of mass


  • Wide base
  • Unstable Object
• High centre of mass

  • Narrow base
  • Stable Object
• Scalar


  A quantity that only has a magnitude (size)
• Vector


  A quantity that has a magnitude (size) and a direction
• Scalar quantities


  • Volume
  • Mass
  • Time
  • Energy
  • Speed
  • Temperature
  • Distance
• Vector quantities


  • Weight force
  • Velocity
  • Acceleration
  • Displacement
• Distance


  The total distance travelled by an object during its motion
• Displacement


  The distance moved in a straight line from the object's original position
• Newton's 3rd law: When two objects interact with each other they exert equal and opposite forces on each other
• Resultant force is the overall or net force when 2 or more forces are acting on a body
• Balanced forces


  Object stays still/ steady speed, object is in EQUILIBRIUM, resultant force is zero
• Unbalanced forces


  Object moves, object speeds up / slows down, resultant force is not zero
• An object can't accelerate forever, because air resistance increases as the object accelerates