Stage 2 Bio Mechanics 2nd Ed Sample Package
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A/ B BI ME HANI2 nd ed.
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1PE STUDIES REVISION SEMINARS
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CONTENTIntroduction to Biomechanics
What is it?Benefits of Biomechanics
Types of motion in Physical ActivityLinearAngularGeneral
Coordination of linear motion Types of forcesKinematic ChainSimultaneous force summationSequential force summation
Stability and BalanceBalanceStabilityCentre of Gravity (COG)Base of Support
Factors affecting balance and stability 2
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Newtons laws of motionForce productionNewtons 1 st Law of motion
InertiaNewtons 2 nd Law of motion
MomentumConservation of momentum
ImpulseFlattening the arc
Newtons 3 rd Law of motion
Projectile motion Trajectory of a projectileFactors affecting flight of a projectile
Angle of releaseHeight of releaseVelocity at take off GravityAir resistance
Spin 3
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2. SEQUENTIALLY Where body parts are moved in sequence to produce a force. Generally used to produce maximal force in whole body actions such
as throwing, kicking and striking E.g. A baseball pitcher, striking in golf, kicking in rugby
.SUMMATION FOR MAXIMAL OR
SUBMAXIMAL FORCE
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PE STUDIES REVISION SEMINARS
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FORCE/MOMENTUM
Body parts move in a sequence to generate the largestforce or acceleration possible. To sequentially produce maximal force effectively, thefollowing principles need to be applied:
1. The stronger and larger muscles of the thighs and trunk are
moved first followed by the smaller and faster muscles2. Sequentially accelerate each body part so that optimummomentum passes from one body part to the next.
3. Each body part should be stable so that the next body partaccelerates around a stable base to transfer momentum
4. Use as many body parts as possible, so force can be appliedover the maximum possible time
5. Follow through is important to prevent deceleration of lastsegment and safe dissipation of force.
6. Ensure all forces are directed towards the target
5PE STUDIES REVISION SEMINARSHome
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-THROWINGBig body parts of legs
and trunk initiatemovement
Wide base providesstable base for
acceleration of each
segment
Maximise number of segments used
Follow throughtowards the target toprevent decelerationof final segment andmaximise momentum
towards the target
6PE STUDIES REVISION SEMINARSHome
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DETERMINING THE CENTRE OFGRAVITY
To determine ones COG, simply draw a box around the objectsouter extremities
Then draw diagonal lines through the box, with the point of intersection determining the objects approximate COG.
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7PE STUDIES REVISION SEMINARS
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Approximate
COG
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More stable Less stable
Low COGHigher COG
Wide base of support 4 point contact Small base of
supp ort 2 point contactLine of gravity in middle of support
STABILITY VARIES WITH BODY POSITION
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NEWTONS 1 ST LAW OF MOTION
Newtons First Law of Motion - Inertia
The size of the force required to change the state of motion of an object depends on the mass of the object.
The greater the mass of the object, the greater the forceneeded to move it.
The 8kg medicine ball has agreater inertia because of its greater mass andtherefore requires a greaterforce to move it
The golf ball on the left willremain stationary on thetee until a force (applied bythe club) is applied to it
10PE STUDIES REVISION SEMINARSHome
A body continues in its state of rest or state of motion unlessacted upon by a force.
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Newtons Second Law of Motion acceleration / momentum
The greater the force applied to an object, the faster theacceleration will be.Acceleration is directly proportional to the force applied.
A small force applied to a ballusing a putter results in slow
acce leration
A large force applied to a ballusing a driver results in faster
acceleration
NEWTONS 2 ND LAW OF MOTION
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The rate of change of acceleration to a body is proportionalto the force applied to it.
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If all other factors are constant (i.e. Speed of release, height of release, spin, air resistance);
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1. ANGLE OF RELEASE
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An angle of less than 45 results in shorterhorizontal distances, shorter vertical distances andshorter flight times This might be useful in the following sports; Throwing in softball, cricket etc, stab pass in
An angle of greater than 45 results in shorterhorizontal distances , greater vertical distances andlonger flight times. This might be useful in the following sports;
High Jump, Pole Vault, punting in AmericanFootball
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PE STUDIES REVISION SEMINARS 13
HORIZONTALMOTION
1. ANGLE OF RELEASE
H
Angle of release =45
Vertical andhorizontal velocity isequalMax horizontaldistance attained
Angle of release >45
Vertical velocity isgreater thanhorizontal height and flighttimehorizontal distance
Angle of release
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