Biomechanics

• Force


  A push or pull altering motion of a body.
• Inertia


  Resistance to change in motion state.
• Velocity


  Rate of change in displacement with direction.
• Momentum


  Product of a body's mass and velocity.
• Acceleration


  Rate of change in velocity over time.
• First Law of Motion


  Object remains at rest or uniform motion unless acted upon.
• Second Law of Motion


  Acceleration is proportional to force applied.
• Third Law of Motion


  For every action, there is an equal opposite reaction.
• Weight


  Gravitational pull on a body; weight = mass x gravity.
• Friction


  Force opposing motion between two surfaces in contact.
• Air Resistance


  Force opposing motion through the air.
• Net Force


  Sum of all forces acting on a body.
• Balanced Forces

  Forces that cancel each other, resulting in no movement.
• Unbalanced Forces


  Forces that cause a change in motion.
• Reaction Force


  Force equal and opposite to an applied force.
• Centre of Mass


  Point where a body's weight appears to act.
• Stability


  Ability to resist motion and return to position.
• Factors Affecting Stability


  Height of centre of mass, line of gravity, base of support.
• Kinematics


  Study of movement in relation to space and time.
• Force Plates


  Measure ground reaction force during human motion.
• Wind Tunnels


  Measure aerodynamic efficiency and forces on objects.
• Advantages of Kinematics


  High accuracy, immediate data, focuses on specific limbs.
• Disadvantages of Kinematics


  Expensive, requires specialized training and equipment.
• force plate advantages


  highly accurate, immediate data, displayed in all planes of movement
• force plates disadvantages


  expensive equipment, specialised equipment, skill may require accommodation
• wind tunnel advantages


  allows control over environmental variables, precise methods, time efficient
• wind tunnels disadvantages


  expensive, specific training, specialised equipment
• 5 effects of forces


  Create motion, accelerates a body decelerates a body, change direction of a body, change shape of a body
• What is friction affected by?


  Roughness of the ground surface,

  Roughness of contact surface,

  Temperature,

  Mass of object
• What is air resistance affected by?


  Velocity,

  Shape,

  Frontal cross-sectional area,

  Smoothness of surface,

  Mass
• What are the lever parts in relation to the body?

  Fulcrum - always a joint

  Effort - muscle

  Lever - bones
• What are the 2 purposes of levers in the human body?


  Generating effort to overcome a load

  Increasing speed of a movement
• What lever has mechanical advantage?


  second class lever
• What lever has an increased acceleration?


  Third class lever
• What's the calculation that links force mass and acceleration?


  Force= mass x acceleration
• What's the calculation that links mass momentum and velocity?


  Momentum = mass x velocity
• How do you calculate velocity?


  velocity = displacement / time taken
• How do you calculate acceleration?


  Acceleration = final velocity-initial velocity/time
• What's the definition of linear motion?


  Movements of a body in a straight line or curved line, where all parts move the same distance in the same direction over the same time
• What's the definition of direct force?


  A force applied through the centre of mass resulting in linear motion