biomechanics

• Biomechanics


  The study of the mechanical aspects of biological systems
• Types of motion


  • Linear motion
  • Angular motion
  • General motion
• Linear motion


  • Movement of a body or object that takes place in a straight line
  • All parts of an object or body move the same distance, in the same direction, at the same time
• Linear motion


  • water
  • skiing
  • bob sleigh
• Angular motion


  • Movement of a body or object in a circle, or part circle, about a fixed axis of rotation
• Angular motion


  • Spinning ice skater
  • Movements of arms and legs at joints when running or swimming
  • Somersault dive
  • Twisting ice skater
• General motion


  • Combination of linear and angular motion
• General motion


  • Running
  • Swimming
• Force


  A "push" or "pull" exerted on an object or body without which movement would not be possible
• Forces can be generated


  • Internally by muscular contractions
  • Externally through the action of weight and frictional forces, including air and water
• Force can


  • Cause a body at rest to move
  • Cause a moving body to accelerate
  • Cause a moving body to decelerate
  • Cause a moving body to change direction
  • Cause a body to change shape
• Newton's 1st law (law of inertia)


  Every body at rest, or moving with constant velocity in a straight line, will continue in that state unless compelled to change by an external force exerted upon it
• Velocity


  Velocity = displacement / time taken
• Momentum


  Momentum = mass x velocity
• Acceleration


  Acceleration = (final velocity – initial velocity) / time taken
• Acceleration


  Acceleration = Force / Mass
• Force


  Force x acceleration (F =ma)
• Newton's 2nd law (law of acceleration)


  The acceleration of a body is proportional to the force causing it, and the acceleration takes place in the direction in which that force acts
• Newton's 3rd law (action/reaction law)


  When one object exerts a force on a second object, there is a force equal in magnitude but opposite in direction exerted by the second object on the first
• Centre of mass


  The point where the weight of the body tends to be concentrated, where the object or body is balanced in all directions
• Centre of mass


  • For a round object this is generally in the middle
  • More complex for the human body especially when moving
• Biomechanics


  The study of human movement and the effect of force and motion on sports performance
• Linear motion


  Movement of a body in a straight or curved line, where all parts move the same distance, in the same direction over the same time
• Key descriptors of linear motion


  • Distance
  • Displacement
  • Speed
  • Velocity
  • Acceleration and deceleration
• Linear motion results from a direct force being applied to the centre of mass of the body
• Centre of mass


  The point at which a body is balanced in all directions
• Newton's first law of motion: A body will continue in its state of rest or uniform velocity unless external forces are exerted upon it
• According to Newton's first law, a body will continue to travel in linear motion indefinitely if uninterrupted
• Useful information to analyse performance in 100m, 400m etc.


  • Speed
  • Velocity
  • Acceleration
  • Over the whole event or for different parts of the event
• Five effects of force


  • Create motion
  • Accelerate a body
  • Decelerate a body
  • Change direction of a body
  • Change the shape of the body
• Linear motion descriptors


  • Distance
  • Displacement
  • Speed
  • Velocity
  • Acceleration/deceleration
• Weight


  Gravitational pull on a body measured in Newtons (N)
• Distance


  Total length covered from start to finish in metres
• Weight (N)


  mass x acceleration due to gravity
• Displacement


  The shortest straight-line route from start to finish measured in m
• Speed


  The rate of change in distance measured in m/s
• Speed = distance/time taken
• Reaction


  Equal and opposite force exerted by a body in response to the action force placed upon it and measured in Newtons (Newton's 3rd Law)
• Friction


  The force which opposes two surfaces in contact, measured in Newtons (N)
• Friction is affected by roughness of ground surface, temperature, area in contact