AS biomechanics

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  • Created by: wistuart
  • Created on: 09-03-18 09:23
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  • AS Biomechanics
    • Principles of biomechanics
      • To analyze performance
      • To refine and improve sporting technique
      • To design new equipment to benefit athletes
      • To prevent injuries of athletes
    • Newton's laws
      • 1.Inertia- A body will continue in a state or rest or constant velocity until an external force acts upon it.
      • 2. Acceleration- The change in motion of a body is proportional to the force applied
      • 3. Reaction- Every action has an equal and opposite reaction
    • Equations
      • Velocity= displacement/time taken (m/s)
      • Momentum= velocity* mass (Kgm/s)
      • Acceleration= (final velocity-initial velocity)/Time taken (m/s/s)
      • Force= Mass* acceleration  (N)
      • Weight= mass* acceleration due to gravity (10m/s/s)  (N)
    • Net forces
      • Net force= 0- This means that a body is in a state of constant velocity or a state of rest.
      • Net force= 1- A body is accelerating
      • A sum of all the forces acting upon a body
      • Net force= -1- A body is decelerating
    • Forces
      • Vertical Forces
        • Weight- The gravitational pull that the earth exerts on a body.
        • Ground reaction force- The equal and opposite reaction to weight which is always present.
      • Horizontal Forces
        • Friction- The force that opposes the motion of two surfaces in motion.
          • Factors affecting friction
            • Roughness of the ground surface- increased roughness=  increased friction
              • Athletes running on rough rubberized trackes instead of grass
            • Roughness of the contact surface- Increased surface of contact surface= increased friction
              • Athletes running with spikes instead of trainers
            • Temperature- increased temperature of contact surface and surface= increased friction
              • F1 drivers have a warm up lap
            • Size of normal reaction- By increasing the  size of reaction friction is increased due to more force
              • shot-putters have a bigger mass meaning they can throw harder and reduce over rotation
        • Air resistance- The force that opposes the motion of a body travelling through the air
          • Factors affecting air resistance
            • Velocity- increased velocity= increased air resistance
              • The faster a runner goes the more Air resistance they will have
            • Shape- the more aerodynamic the shape= less air resistance
              • Cyclists use a teardrop helmet as it is more streamline than a conventional helemt
            • Frontal cross sectional area- decreased frontal cross sectional area= reduced air resistance
              • The crouched position of skiers in straights
            • Smoothness of surface- the smoother the surface the less air resistance
              • The smooth lycra suits of sprinters
      • Measured in newtons
    • Analysis through technology
      • Limb kinematics- 3d optical motion analysis- can be used to improve technique
      • Force plates- measures ground reaction forces-focuses on power output-when an object makes contact the force plate produces an electrical output proportional to the force applies
      • Wind tunnels- Used to develop drag reduction systems and used to see how aerodynamic an object is
    • Centre of mass and stability
      • Centre of mass- is the point at which the body is balanced from all points.
      • stability is the ability of the body to reduce motion and stay at rest
        • Factors affecting stability
          • Mass of the body- The greater the mass of the body the greater the stability due to its increased inertia
            • Prop forwards in rugby can withstand great applied forces
          • Height of the Centre of mass- The lower the centre of mass the greater the stability
            • When gymnasts land they bend their knees to avoid falling over
          • Base of support- the greater the base of support the greater the stability
            • When props move their feet further than shoulder width in a scrum
          • line of gravity- the line that extends from the centre of mass downwards- more central the line of gravity to base of support the greater the stability
            • A basketball player taking a free throw stands square
    • Lever systems
      • components of a lever; - lever (BONE) - Fulcrum (JOINT)   -Effort (Antagonist MUSCLE) -Load(WEIGHT OR Resistance)
      • 1st class- Fulcrum in the middle
        • Extension of the neck
      • 2nd class- Load is in the middle
        • Ball of the foot in take off phase of a jump
          • mechanical advantage- effort arm is greater than the load arm
      • 3rd class- Effort is in the middle
        • Flexion of the elbow in bicep curl
          • mechanical disadvantage- load arm is greater than the effort arm

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