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# Biomech noteskoodle

## on Nov 25, 2010

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## Biomech noteskoodlePresentation Transcript

• Bio mechanics
• Biomechanics studies what makes a body move. It studies internal and external forces (remember a force is a push or a pull) that act on the body and other objects. It is possible to work out how your body should move in order to perform a task more efficiently. So for example we can use biomechanics to make you a better player!
• Biomechanics Summary
• Balance and Stability
• Newton's Laws
• Force Summation
• Projectile Motion
• Levers
• Balance and Stability
• This is defined as the ability to hold or maintain a position in space
• St ability generally depends on:
• The location of the centre of gravity (COG) with respect to the base of support.
• The direction of forces involved
• Balance and Stability
• Centre of Gravity is the point in the body at which all body parts are in balance.
• In the anatomical position males generally have a higher COG than woman.
• The body rotates around the COG
• Four Main Principles of Stability
• The closer the line of gravity is to the centre of the base of support, the greater the probability of maintaining balance
• 2. The broader the base of support, the greater the probability of maintaining balance .
• Four Main Principles of Stability
• 3. Our balance is improved when we lower our Centre of Gravity in relation to the base of support. eg:
• 4. The further one part of the body moves away from the line of gravity, the probability of maintaining balance decreases unless another body part moves to compensate for it. eg.
• Balance and Stability
• We can further increase stability:
• Increase Friction eg________
• Lean into an incoming Force eg______
• Increase Rotation eg________
• Increase Mass eg________
• Newton’s Laws of Motion
• Newton’s First Law: Law of Inertia
• An object at rest tends to remain at rest unless it is acted on by an external force.
• An object in motion tends to remain in motion and to travel in a straight line with uniform velocity unless acted on by an external force.
• Newton’s Laws of Motion
• Newton’s Second Law: Law of Acceleration
• When a force acts on a body, it’s resulting change in momentum is proportional to the force causing it and inversely proportional to the mass
• Force = Mass x Acceleration
• Newton’s Laws of Motion
• Newton’s Third Law: Law of Action/Reaction
• For every action there is an equal and opposite reaction
• Force Summation
• To give an object momentum eg throwing, kicking, hitting, the amount of momentum given to the object is determined by the ‘sum of all forces generated by each body part’.
• Force Summation
• Five Basic Guidelines to generate optimal force:
• Use of body segments
• Stretch out
• Sequencing of Body segments – larger first
• Timing of Body Segments
• Full Range of Motion
• See Handout
• Force Summation Note importance of: Stabilisation Timing
• Force Summation Consider force summation in relation to drawing and driving.
• Projectile Motion
• Any object released into the air is a projectile. eg?
• Six Factors Affect a Projectile’s Path
• Gravity
• Air resistance
• Speed of Release
• Angle of Release
• Height of Release
• Spin
• Projectile Motion
• Of the six, the most important factors are Gravity which acts to decrease the height a projectile will travel and Air Resistance which acts to decrease distance.
• Note a projectile will travel in a parabolic curve unless acted on by another influence
• Gravity and Air Resistance
• Gravity
• Effects an object at a constant of 10N
• Gravity is a weak attractive force but we cannot escape it!
• Air Resistance
• Effects the path of a projectile depending on its mass, speed and/or surface area.
• Eg Graph the path of a petanque ball vs a shuttlecock
• The greater the speed of release, the greater the distance traveled.
• Two Parts:
• Initial Vertical Speed
• Initial Horizontal Speed
• The greater the vertical speed: the higher and longer (time) the projectile will fly.
• The greater the horizontal speed: the further it will fly.
Speed of Release
• Speed of Release Force = Mass x Acceleration To increase force can increase one or both. How? This may create problems such as … Remember Newton’s Second Law:
• Angle of Release
• You need an optimum angle to maximise the benefits of vertical and horizontal velocity.
• If the angle is too high:
• If the angle is too low:
• Angle of Release
• Angling of the release of the bowl allows for what to occur?
• Height of Release
• As the Height of Release increases, so does the distance that will be gained.
• Not really relevant in bowls but definitely in Petanque – How?
• Spin
• In order to cause rotation a force has to be applied to one side of the COG.
• Topspin Causes:
• Backspin Causes:
• Levers
• Levers consist of 3 parts
• Resistance
• Effort
• Fulcrum or Pivot
1 2 3
• Levers
• Two main functions:
• To increase the resistance that can be moved eg__________
• To increase the velocity at which an object will move with a given force. eg _______
• There are 3 types of levers. See handout .