biomechanics

• mass(kgs)


  a measure of how much matter is in an object. remains the same regardless of the gravity acting on the object.
• inertia


  the tendency of an object to resist change in its state of motion
• force


  a 'push' or 'pull' with the objective of changing the state of motion of the object

  force= mass x acceleration

  unit- newtons
• momentum 


  the amount of motion an object has and its resistance to changing that motion

  momentum= mass x velocity

  unit- kg m/sec
• conservation of momentum 


  the total momentum of objects before a collision is equal to the total momentum of the objects after the collision.

  eg.

  the total momentum of a golf club and ball before collision is equal to the total momentum of the club and ball after the collision
• summation of momentum - simultaneous 


  involves all body parts acting together at the same time to generate force (sprint start)
• summation of momentum - sequential


  involves all body parts contributing in sequence to generate force (golf drive)

  principles of sequential force summation-

  -use as many body parts as possible

  -start with larger(slower) body parts and move to smaller(faster) body parts

  -ensure a stable base for the next body part to accelerate from

  -correct timing/sequential

  aim- increase velocity on release
• impulse


  the change in momentum of a body

  impulse= force x time
• angular momentum 


  the amount of angular motion possessed by a body

  angular momentum= moment of inertia x angular velocity
• moment of inertia


  an object's reluctance to rotate

  moment of inertia= mass x radius2

  
  

  The location of the mass is important in reducing or increasing an objects moment of inertia​

  • mass closer to axis of rotation = easier to rotate​
  • mass further from axis of rotation = harder to rotate
• torque


  the tendency of an object to rotate

  torque= force x lever arm
• lever arm


  distance from axis of rotation to line of force
• distance


  linear- path travelled from start to finish, regardless of direction (m)

  angular- sum of all angular changes a body undergoes (degrees)
• displacement


  linear- change of position from initial to final

  angular- difference between the initial and final angular position (degrees)
• linear speed and velocity

  speed- ratio of the distance covered in the time taken

  = distance / time

  velocity- ratio of displacement to the time taken

  = displacement / time

  both (m/sec)
• angular speed and velocity

  speed- angular distance covered in the time taken

  = angular distance / time

  velocity- rate of change of angular displacement over time

  = angular displacement / time​

  both (degrees/sec)    
• linear acceleration

  change in velocity in a given period of time
• angular acceleration

  change in angular velocity in a given period of time