4.3 Fundamentals of Biomechanics

• Force = the push or pull on an object

  • unit: Newtons
• Speed = maximumrate at which person is able to move their body

  • unit : m/s
  • scalar quantity
• Velocity is the speed of an object in a certain direction

  • unit: m/s
  • vector quantity
• Displament (s) is distance measured in certain direction

  • unit: metre
  • vector quantity
• symbol for speed and velocity is v
• acceleration (a) is the rate of change of velocity

  • unit: m/s2
  • vector quantity
• Momentum (p) is the amount of motion posessed by a moving object

  • unit: kg m/s
  • vector quantity
• Impulse (J)= Force x Time
• Center of mass is the mathematical point around which the mass of a body or object is evenely distrtibuted
• 1st Class lever:

  • load, falcrum, effort
  • load: hand
  • Falcrum: elbow
  • effort: Triceps contracting
• 2nd class lever:

  • effort, load, fulcrum
  • Effort:Gastrocnemius
  • Load: Tibia/Fibula
  • Fulcrum: Tarsals
• 3rd Class Lever:

  • Load, Effort, Fulcrum
  • Load: Hand
  • Effort: tendons in the forarm
  • Fulcrum: Elbow
• Newton's 1st Law: Law of Inertia:

  • any object will remain and rest or in constant motion unless acted upon by an external force
  • Ball will remain at rest unless acted on by an outside force like player's foot or a golf club
  • Ball will travel in constant motion unless acted upon by an external force like wind, trees, air resistance, gravity
• Newton's second law: Law of acceleration:

  • F= m x a
  • F= mass x acceleration
  • the force applied to an object is equal to the mass of an object multiplied by the acceleration required

  Basketball:

  • If a 70kg footbal player runs into a 130kg football player, both will experience same amount of force but the smaller player will have a greater acceleration out of the collision because of his smaller mass
• Newton's 3rd Law: Law of Reaction:

  • Every action has an equal and opposite reaction

  Tennis:

  • the racket applies a certain amount of force to the tennis ball and the tennis ball applies the same amount of force back to the tennis racket

  Running Blocks:

  • athlete pushes downwards and backwards into sprintblock and the block returns that force in an upward and forward motion, propelling the athlete forwards
• Conservation of Momentum:

  • the moment before a collision is the same as the momentum after a collision
• Angular Momentum (L) = Moment of Inertia (I) x Angualar Velocity (W)
• Relationship between angular momentum, moment of inertia and angular velocity

  • Angular momentum is the product of moment of inertia and angular velocity
• Concept of angular momentum in relation to sporting activities:

  Angular momentum is constant, however, during the rotation, the athlete can manipulare angular velocity and moment of inertia
• Explore the factors that affect projectile motion at take off or release

   

   

  Projectile motion:

   

  • Any body that is given initial velocity and follows a path determined by the effect of gravity and air resistance

   

  • Path followed by a projectile is called a trajectory

   

  • Projectile is affected by horizontal and vertical motion - which are independent of each other

   

  • Soeed of release and angle of release can be used to calculate how far the object will travel

   

   

   

  Factors that affect projectile motion: 

   

  1. Angle of release
  2. Height of release
  3. Speed of release

   
• Factors that affect projectile motion: 

   

  1. Angle of release
  2. Height of release
  3. Speed of release

   
• Bernouli principle refers to an inverse relationship between airflow velocity and air pressure