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Physical EducationUnit 1AREA of study 2Biomechanical movement principles

Pages 62 - 135LabsClassworkHomeworkParticipation/Attendance (80%)Work RequirementsCase study analysis or data analysisWeek 4 - 5 (term 2)

Assessment TasksBiomechanics is the study of living things from a mechanical perspective and is essentially the physics behind human movement.

The application of the laws and principles of mechanics to living organisms.(Mechanics of Sport 1997)

The science of human movement. It applies the laws of mechanics and physics to human performance. (Live It Up 2006)

What is biomechanics?A scientist who is involved in:Human performance analysisThe analysis of forces in sport and physical activitiesHow injuries occur in sportInjury prevention and rehabilitative treatment methodsThe design and development of sporting equipment.What is a biomechanist?CinematographyComputer and digital analysisWind tunnelsResistance pools/swimming flumesElectromyographyWhat technology/equipment does a biomechanist use?

MotionForce productionApplication of forceNewtons three laws of motionMomentumLeverageImpact and frictionBalance and stability**Equipment design**Topics we will cover:KEY KNOWLEDGEKEY SKILLSNewtons laws of motions incorporating force, mass and weight, acceleration and inertia applied to a range of sporting and physical activities.The application of force summation to different sports and physical activities How is momentum conserved and transferred during different sportsFactors affecting angular motion including torque, angular velocity, momentum and moment of inertia and their application to sporting activitiesThe coefficient of restitution and elasticity of different sports equipment.How does rebound velocity effect performances?Explain the application of key biomechanical principles to a range of sporting movements by using correct termsInvestigate and interpret graphs of biomechanical principles pertaining to movementsParticipate in, analyse and report on a range of practical activities that consider biomechanical principlesUse biomechanical principles to critique the effectiveness of different movementsAnalyse different sporting actions to identify similarities and differences as well as the correct application of biomechanical principles to improve performance

The bodys resistance to change its state of motion.Resistance to beginning movement Resistance to changing its movement whilst moving.The heavier an object, the greater its inertia.Eg.InertiaTheyre different!

Mass is the amount of matter an object is made up of. Mass is usually measured in kilograms.

Weight is the force exerted on an object by gravity and is directly proportional to its mass.

Mass & WeightA push or a pull acting on an object.(from this years text)

Any pushing or pulling activity that tends to alter the state of motion of a body.

Forces on the body can be internal or external.

Examples of forces...

ForcesGravityThe pull towards the centre of the earth.FrictionThe rubbing of the surface of one thing against that of another.Air resistanceThe resistance against a body created by air.Water resistanceThe resistance against a body created by water.External ForcesFriction is the force that occurs whenever one body moves across another surface.Friction always opposes motion.FrictionOccurs when two objects slide over one another.Eg.Sliding FrictionRolling FrictionWhen an object rolls across a surface.Eg.

There are two types of internal forces:Isometric force (without motion)Muscular contractions create force without changing length or creating movement.Eg.Isotonic force (with motion)Force is sufficient enough to change the state of motion.Eg.Eg.

Internal ForcesSub-maximal forceUsing a less than maximal force to create a successful, more accurate performance.Eg.Maximal force (force summation)Can be achieved:Simultaneously, where an explosive action of all body parts occurs at the same time.Eg.Sequentially, where body parts move in sequence.Eg.Internal ForcesLab #5 due

Friday, 3rd MayPages 101-102

Newtons first law of motioninertiaNewtons second law of motionAcceleration/momentumNewtons third law of motionAction/reactionNewtons Laws of MotionA body will remain at rest or continue in a constant state of motion unless acted upon by an external force.

Examples...Newtons First Law of Motion: Inertia

A force applied to an object will produce a change in motion (acceleration) in the direction of the applied force that is directly proportional to the size of the force.

Examples...

Newtons Second Law of Motion: Acceleration/MomentumFor every action there is an equal and opposite reaction.

The total momentum of two objects before impact or contact will equal the total momentum after impact.Newtons Third Law of Motion: Action/Reaction

The motion possessed by a moving body.

Momentum = mass X velocityThe greater an objects momentum, the further it will travel and harder it is to stop.Which has greater momentum:A marathon runner weighs 60kg and is jogging at 10kmh.A footballer weighs 90kg and is walking at 6kmh.(Momentum is measured in kg m/s)MomentumAn object that is not moving has zero momentum because it has no velocity

If two objects have the same mass but different velocities, the one moving quickest has the greater momentum

If two objects have the same velocity but different masses, the one with the greatest mass also has the greater momentum

Total momentum before a collision equals total momentum after the collision (but can be affected by external forces)e.g.

A hockey stick is used to hit a stationary ball (zero momentum before being hit)Before hitting the ball the stick has all of the momentum which is then transferred to the ball at point of impact (the stick still has momentum during the follow through)

Conservation of MomentumPage 106Questions 1, 2, 3, 4 & 5Thinking things throughThe momentum of a rotating object or body.AM = moment of inertia X angular velocityAngular MomentumIs a bodys resistance to beginning rotation.The greater the distance from the axis to the end of the body (ie. to head of tennis racquet), the greater the moment of inertia.Moment of Inertia = mass x radius2Eg.Moment Of Inertia

Angular momentum is conserved when a body is in flight and there is an inverse relationship between angular velocity and moment of inertia

Conservation of Angular MomentumWhat can coaches/parents do to reduce the moment of inertia of childrens sporting equipment?Moment of InertiaImpulse = force X timeWhere force equals velocity or speed, and time is the length of time over which the force was applied.Impulse is the reason objects momentums change.To change an objects momentum, a force must be applied to the object over a period of time.

Impulse

The amount of rebound potential of a ball.When a ball hits a surface it changes shape for a short time before rebounding and returning to its previous shape. Factors affecting CoR:Contacting surfacesTemperatureImpact velocityCoefficient of RestitutionImpactCoR is calculated by using the following formula:CoR = height of reboundheight of release

ObjectHeight of releaseHeight of reboundCoRGolf ball2m1.6m0.894Tennis Ball1m0.6m0.775Coefficient of RestitutionBallHeight of releaseHeight of reboundCoefficient of restitutionTennis ball1mHockey ball1mNerf ball1mBasketball1mTable tennis ball1mSoft-cross ball 1mCoR - carpetBallHeight of releaseHeight of reboundCoefficient of restitutionTennis ball1mGolf ball1mSoccer ball1mBasketball1mSquash ball1mSoft-cross ball 1mNerf ball1mTable tennis ball1mSoft ball1mCoR - concretePage 117Chapter Review Questions