biomechanical principles

• first law of linear motion suggests that an object stays at rest unless acted on by an external force
• newtons second law suggest that force is equal to the acceleration multiplied by the mass

  acceleration is proportional to the size of the force
• newtons third law suggests that every force has an equal and opposite reaction
• scalar quantites


  only magnitude/size:

  • speed
  • distance
  • mass
  • temperature
• vector quantities


  have both magnitude and direction:

  • weight
  • acceleration
  • displacement
  • velocity
• factors affecting stability


  height of centre of mass - lower = more stable

  position of line of gravity - should be more central over base of support = more stable

  area/wdth of base of support - more contact points, larger base becomes more stable

  mass of performer - often the greater the mass the more stable
• centre of mass


  concentration of mass, or the point of centre of balance. difficult to identify by lifting arms up it changes. males higher than female centre of mass. broader shoulders vs broader hips
• speed = distance / time (m/s)

  distance is the length of pathway a body follows