Biomechanics

• Linear Motion


  Motion in a straight or curved line, with all body parts moving the same distance at the same speed in the same direction.
• Inertia


  the resistance an object has to a change in its state of motion
• Newton's first law


  A force is required to change the state of motion
• Newton's second law


  The magnitude and direction of the force determines the magnitude and direction of the acceleration.
• Newton's third law


  For every actions there is an equal and opposite reaction.
• Ground reaction force


  The equal and opposite force exerted on a performer who applies a muscular force on the ground.
• Scalar quantity


  When measurements are described in terms of just their size or magnitude
• speed eqaution


  speed=distance/time
• Centre of mass


  The point of balance
• Line of gravity


  The line extending vertically downwards from the centre of mass.
• Impact of the height of centre of mass

  Lower centre of mass increases stability
• Impact of the position of the line of gravity

  Line of gravity should be central over the base of support to increase stability
• Impact of the area of the support base

  The more contact points means the area of the support base is bigger and there is more stability
• Impact of the mass of the performer


  The greater the mass of the performer provides more stability
• Fulcrum


  The point about which the lever rotates
• Resistance


  The weight to be moved by the lever system
• Effort


  The force applied by the user of the lever system
• First class lever


  The fulcrum lies between the effort and resistance
• Second class lever


  the resistance is between the fulcrum and the effort
• Third class lever


  The effort is between the fulcrum and the resistance
• Force arm


  The length of the line between where the fulcrum and effort are labelled
• Resistance arm


  The length of the line between where the fulcrum and the resistance are labelled
• Mechanical advantage


  Where the force arm is longer than the resistance arm
• Mechanical disadvantage


  Where the resistance arm is longer than the force arm
• scalar quantity


  When measurements are described in terms of just their size or magnitude
• Vector quantity


  a quantity that has both magnitude and direction
• Weight calculaton


  Mass x gravity = weight
• Distance


  Measured in metres and is the path a body takes as it moves from the start to finish position
• Displacement


  The shortest route in a straight line from the start to the finish
• Speed


  The distance an object travels per unit of time

  S=d/t
• Velocity


  the speed of an object in a particular direction

  Velocity = displacement/time
• Distance time graph


  Shows the distance travelled over a period of time
• Velocity time graph


  shows how velocity is related to time
• Acceleration


  Measured in m/s^2 and is the rate of change of velocity

  acceleration = change in velocity/time
• Momentum


  The product of an object's mass and velocity

  mass x velocity = momentum
• External force


  comes from outside the body e.g. friction, air resistance & weight
• Internal force


  Is generated by the skeletal muscles
• Weight


  The gravitational force exerted on an object
• Reaction force


  Occurs when 2 bodies are in contact with one another
• Friction


  Occurs when 2 or more bodies are in contact with one another