Biomechanics

• Newtons 1st Law of inertia 


  unless acted on by an external force, an object will remain at rest or at constant speed.
• Newtons 2nd law of acceleration

  Force = Mass x Acceleration
• Newtons 3rd law of action/reaction

  For every action there is an equal and opposite reaction
• Factors affecting stability


  Height of the centre of mass, area of base of support, mass of performer, position of the line of gravity
• Mechanical Advantage 


  A large load can be lifted with little effort. The effort arm is longer than the load arm.
• Mechanical Disadvantage 


  Takes a lot of effort to lift a relatively small load
• Impulse 


  The time taken for a force to be applied to an object or body. Impulse (Ns) = force (N) x time (s)
• Angular Motion


  Movement that takes place around an axis or fixed point
• 1st Angular Law


  A rotating body will continue with constant torque until a large enough external force is acted upon it
• 2nd Angular Law


  The rate of change of angular motion is proportional to the force changing it
• 3rd Angular Law


  When a torque is applied there is an equal and opposite force
• Angular Displacement


  The smallest change in angle between the start and finish points of a rotation. Measures in Degrees and Radians.
• Angular velocity


  The rotational speed of an object. Refers to the rate of change of angular displacement
• Angular Acceleration


  The rate of change of angular velocity
• Angular momentum


  moment of inertia x angular velocity
• Factors affecting horizontal displacement

  Gravity, Air resistance
• Forms of Drag


  Surface Drag - refers to friction Form Drag - refers to streamlining
• The Bernoulli Principle


  The angle of release of an object affects how air passes over the top and bottom of an object. Air molecules exert less pressure when they travel faster and most pressure when they travel slower.
• Upward Lift


  (discus) At a 45 degree angle of release, air will travel quicker over the top of the discus causing low pressure and slow at the bottom causing high pressure. pressure moves from high to low causing it to lift higher
• Downward Lift 


  (cyclist) streamlined position means air will travel slower above the cyclist causing high pressure. Air will travel quickly against the cyclist creating low pressure. Pressure moves from high to low allowing the cyclist to keep speed whilst cornering
• Angular Velocity
• Angular velocity


  Angular displacement / Time
• Angular Acceleration 


  change in velocity / time
• moment of inertia


  mass x distribution of mass from the axis
• momentum


  mass x velocity