2 Mechanics

• S = (v+u)/2 x t
• Explain why the equations of motion should not be used to determine the maximum speed of the child.

  Steepness of the slide changes/varies

  so acceleration changes/varies

  Equation of Motion needs acceleration to be constant
• Explain why the equations of motion should not be used to determine the maximum speed of the child.

  Steepness of the slide changes

  So acceleration changes

  Equation of motion require a constant acceleration

  
• What is meant by equilibrium

  Zero resultant force

  Zero moment
• What is meant by the centre of gravity

  point at which the weight of an object may act
• Moment

  mass x velocity
• Explain how the forces on the gymnast affect the vertical acceleration while she is in contact with the trampoline

  • Weight of gymnast acts downwards
  • Normal contact force from trampoline acts upwards
  • As she moves upwards normal decreases
  • Normal is zero when she is off the trampoline
  • Resultant force is the difference between weight and normal force
  • When normal is less than the weight than the acceleration is downwards