Stage 2 Bio Mechanics 2nd Ed Sample Package

8/8/2019 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



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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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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


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);

PE STUDIES REVISION SEMINARS 12

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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Stage 2 Bio Mechanics 2nd Ed Sample Package