BIOMECHANICAL PRINCIPLES AND APPLICATIONS

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BIOMECHANICAL PRINCIPLES AND APPLICATIONS
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BIOMECHANICS

• HOW PHYSICAL FORCES AFFECT PERFORMANCE

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SCIENTIFIC MODELS

• REDUCE SKLLLS TO THEIR ESSENTIALS
• A BASIS FOR UNDERSTANDING OF HOW THINGS WORK
• AID IN BEHAVIOURAL PREDICTIONS
• HOW THE BALL WILL BEHAVE(ACT) DURING FLIGHT
  WITH A SPIN

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EQUILIBRIUM

• PERFECT SITUATION
• WHEN THE SUM OF FORCES 0
• NO CHANGE IN MOVEMENT

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CONSERVATION OF ENERGY

• ENERGY CAN NEVER BE CREATED OR DESTROYED
• ONLY CONVERTED FROM ONE FORM TO ANOTHER
• CHEMICAL ENERGY FROM FOOD CONVERTED INTO
  MECHANICAL ENERGY FOR MOVEMENT

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NEWTONS THREE LAWS OF MOTION
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1. LAW OF INERTIA

• AN OBJECT IN MOTION STAYS IN MOTION, AN OBJECT AT
  REST STAYS AT REST UNLESS AN EXTERNAL FORCE IS
  APPLIED
• SOCCER BALL
• BOOK ON TABLE

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2. LAW OF ACCELERATION

• F M x A
• FORCE MASS x ACCELERATION
• A speeding bullet and a slow moving train both
  have tremendous force. The force of the bullet
  can be attributed to its incredible acceleration
  while the force of the train comes from its great
  mass.

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3. LAW OF REACTION

• FOR EVERY ACTION THERE IS AN EQUAL AND OPPOSITE
  REACTION

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BIOMECHANICS LABS

• EXERCISE 15.4

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CENTRE OF MASS (CENTRE OF GRAVITY)

• MASS MORE CORRECT AS GRAVITY WILL NOT CHANGE
  CENTRE OF MASS
• IMAGINARY POINT OF BALANCE
• BODY FOLLOWS CENTRE OF MASS
• PLACEMENT CRITICAL FOR PROPER SKILL EXECUTION

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LINEAR MOTION

• MOVEMENT IN A STRAIGHT LINE (APPROX)
• FORCE APPLIED AT CENTRE OF MASS

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ROTATIONAL MOTION

• MOVEMENT ABOUT AN AXIS
• FORCE NOT APPLIED AT THE CENTRE OF MASS
• OFF TO THE SIDE

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ACCELERATOIN

• CHANGE IN VELOCITY (SPEED) OVER TIME
• STRAIGHT LINE

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FORCE AS A VECTOR

• MOVEMENTS ARE NOT IN A STRAIGHT LINE
• PUSH OR PULL OF A CERTAIN AMOUNT IN A PARTICULAR
  DIRECTION
• RUNNING ? FORWARD AND VERTICAL FORCES COMBINED

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ANGULAR ACCELERATION

• APPLIES TO CHANGE IN VELOCITY DURING ROTATION

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RADIUS OF GYRATION

• AVERAGE DISTANCE FROM THE AXIS OF ROTATION
• AFFECTS SPEED OF ROTATION
• FIGURE SKATING

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CLASSES OF LEVERS

• FIRST CLASS ? TEETER TOTTER
• FULCRUM IS BETWEEN FORCE AND RESISTANCE (LOAD)

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• SECOND CLASS ? WHEELBARROW
• RESISTANCE BETWEEN FORCE AND FULCRUM

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• THIRD CLASS ? SNOW SHOVELLING
• FORCE BETWEEN FULCRUM AND RESISTANCE

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THE SEVEN PRINCIPLES OF BIOMECHANICS
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PRINCIPLE 1

• The lower the center of gravity, the larger the
  base of support, the closer the line of gravity
  to the center of the base of support, and the
  greater the mass, the more stability increases.
• 3 point stance

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PRINCIPLE 2

• The production of maximum force requires the use
  of all the joints that can be used.

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PRINCIPLE 3

• The production of maximum velocity requires the
  use of joints in order from largest to smallest ?
  Kinetic Chain

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PRINCIPLE 4

• The greater the applied impulse, the greater the
  increase in velocity
• Impulse
• Application of force over a period of time that
  creates a change in the amount of momentum an
  athlete or object has ? Force x Length of time
  which force is applied
• ?Pushing a stalled car

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PRINCIPLE 5

• Movement usually occurs in the direction opposite
  that of the applied force

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PRINCIPLE 6

• Angular motion is produced by the application of
  a force acting at some distance from an axis,
  that is, by a torque

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PRINCIPLE 7

• Angular momentum is constant when an athlete or
  object is free in the air