Knes 300 - Principles of Human Movement Course Objectives Course Objectives 1) Learn about the...

Knes 300 - Principles of Human Knes 300 - Principles of Human MovementMovement

Course ObjectivesCourse Objectives

1) Learn about the relationship between 1) Learn about the relationship between mechanical principles and moving bodies. mechanical principles and moving bodies.

2) Apply your knowledge of these 2) Apply your knowledge of these mechanical principles to well-known skills.mechanical principles to well-known skills.

Why analyze movement?Why analyze movement?

- - Minimize injury, maximize performance, Minimize injury, maximize performance, optimize technique.optimize technique.

Knes 300 - Principles of Human Knes 300 - Principles of Human MovementMovement

Qualitative vs. Quantitative ApproachesQualitative vs. Quantitative Approaches

QualitativeQualitative

Description of quality without the use of Description of quality without the use of numbers.numbers.

QuantitativeQuantitative

Involving the use of numbers.Involving the use of numbers.

Ex. Long jump - “That was a long jump” Ex. Long jump - “That was a long jump” vs. the jump was 18 feet in lengthvs. the jump was 18 feet in length

Qualitative vs. Quantitative Qualitative vs. Quantitative DescriptorsDescriptors

QualitativeQualitative goodgood poorpoor longlong heavyheavy flexedflexed rotatedrotated dopedope tighttight

QuantitativeQuantitative six meterssix meters three secondsthree seconds fifty turnsfifty turns two playerstwo players ten dollarsten dollars 45 degrees45 degrees 55 mph55 mph

Qualitative vs. Quantitative Qualitative vs. Quantitative DescriptorsDescriptors

Qualitative does not mean ‘general’.Qualitative does not mean ‘general’.

A man walking down the street may also be stated A man walking down the street may also be stated ‘a man is walking very slowly, appears to be ‘a man is walking very slowly, appears to be leaning to the left, and is bearing weight on his leaning to the left, and is bearing weight on his right leg for as short a time as possible’.right leg for as short a time as possible’.

Both Q and Q are important in the biomechanical Both Q and Q are important in the biomechanical analysis of human movement and while analysis of human movement and while researchers rely heavily on quantitative researchers rely heavily on quantitative techniques, clinicians, coaches, and teachers or techniques, clinicians, coaches, and teachers or physical activities regularly employ qualitative physical activities regularly employ qualitative observations of their patients, athletes, or observations of their patients, athletes, or students to formulate opinions or give advise.students to formulate opinions or give advise.

BiomechanicsBiomechanics

The science involving the study of biological The science involving the study of biological systems from a mechanical perspective.systems from a mechanical perspective.

Statics and Dynamics are two major sub-Statics and Dynamics are two major sub-branches of mechanics. Statics is the study branches of mechanics. Statics is the study of systems in a state of constant motion (at of systems in a state of constant motion (at rest or constant velocity). Dynamics is the rest or constant velocity). Dynamics is the study of systems in which acceleration is study of systems in which acceleration is present.present.

Kinematics - describes the appearance of Kinematics - describes the appearance of motion.motion.

Kinetics - the study of forces associated Kinetics - the study of forces associated with motion (since F=ma then acceleration with motion (since F=ma then acceleration is important variable in kinetic analyses).is important variable in kinetic analyses).

Chapter 1 - Sport Chapter 1 - Sport MechanicsMechanics

Mechanical PrinciplesMechanical Principles TechniqueTechnique Traditional training methodsTraditional training methods How to use this informationHow to use this information


Mechanical PrinciplesMechanical Principles

Basic rules that govern an athlete’s Basic rules that govern an athlete’s actions.actions.

Ex. Ex.

- Diver and gravity - optimal flight - Diver and gravity - optimal flight pathpath

- Wrestlers helped by gravity when - Wrestlers helped by gravity when getting opponent off balancegetting opponent off balance

- Ski jumpers using air resistance- Ski jumpers using air resistance


TechniqueTechnique

- Patterns and sequence of movements - Patterns and sequence of movements that the athletes use to perform a sport that the athletes use to perform a sport skill.skill.

- Certain sports include a single skill such - Certain sports include a single skill such as discus throwing while tennis includes as discus throwing while tennis includes forehands, backhands, serves etc.forehands, backhands, serves etc.

- Each skill has a specific objective that - Each skill has a specific objective that with ‘good’ technique may be achieved with ‘good’ technique may be achieved with the highest degree of efficiency and with the highest degree of efficiency and success.success.


Traditional training methodsTraditional training methods- Many coaches and athletes still follow old, - Many coaches and athletes still follow old, traditional methods in their workouts.traditional methods in their workouts.

- Trial and error methods demonstrate a lack - Trial and error methods demonstrate a lack of understanding of mechanical principles.of understanding of mechanical principles.

- Copying world champions disregard - Copying world champions disregard differences in physique, training and maturity.differences in physique, training and maturity.

- Analyze performances and teach movement - Analyze performances and teach movement patterns that produce efficient technique patterns that produce efficient technique leading to better performances.leading to better performances.


How to use this informationHow to use this information- Learn to observe, analyze, and correct errors - Learn to observe, analyze, and correct errors in performance.in performance.

- Assess the effectiveness of innovations in - Assess the effectiveness of innovations in sport equipment.sport equipment.

- Assess training methods for potential safety - Assess training methods for potential safety problems.problems.

- Assess the value of innovations in the ways - Assess the value of innovations in the ways sport skills are performed.sport skills are performed.

- Know what to expect from different body - Know what to expect from different body types and different levels of maturity.types and different levels of maturity.

Chapter 2 - Starting with Chapter 2 - Starting with BasicsBasics

Body weightBody weight MassMass InertiaInertia Speed, Velocity and AccelerationSpeed, Velocity and Acceleration GravityGravity ForceForce VectorsVectors ProjectilesProjectiles


Body weightBody weight

- - Newton’s third law states that “For every Newton’s third law states that “For every action there exists an equal AND opposite action there exists an equal AND opposite reaction”reaction”

- Body’s mass pulls on the earth and the earth’s - Body’s mass pulls on the earth and the earth’s mass pulls on the body. Scale reading reflects mass pulls on the body. Scale reading reflects this mutual pulling taking into account the this mutual pulling taking into account the earth’s earth’s gravitationalgravitational pull. The earth’s pull. The earth’s gravitational pull varies according to location gravitational pull varies according to location (the further AWAY from the center of the earth, (the further AWAY from the center of the earth, the smaller the gravitational pull - the less you the smaller the gravitational pull - the less you weigh).weigh).

Acceleration at Sea Level Acceleration at Sea Level by Latitudeby Latitude

LatituLatitudede

AcceleratioAccelerationn

LocationLocation

00 9.7809.780 Nairobi, KenyaNairobi, Kenya

1010 9.7829.782 Caracas Caracas VenezuelaVenezuela

2020 9.7869.786 Honolulu, Honolulu, HawaiiHawaii

3030 9.7939.793 Houston, TexasHouston, Texas

4040 9.8029.802 Denver, Denver, ColoradoColorado

5050 9.8119.811 Bonn, GermanyBonn, Germany

6060 9.8199.819 Anchorage, Anchorage, AlaskaAlaska


MassMass- All objects that have - All objects that have substancesubstance or or mattermatter have mass.have mass.

- The human body is composed of bones, - The human body is composed of bones, muscles, fat, tissues and fluids all of which muscles, fat, tissues and fluids all of which are substance or matter and have mass.are substance or matter and have mass.

- A heavyweight wrestler has more mass - A heavyweight wrestler has more mass than a gymnast resulting in greater than a gymnast resulting in greater attraction between the earth and the attraction between the earth and the wrestler than between the earth and the wrestler than between the earth and the gymnast.gymnast.


InertiaInertia- Resistance to action or to change.- Resistance to action or to change.- The desired of an object to continue - The desired of an object to continue doing whatever it’s doing - even when doing whatever it’s doing - even when it’s moving.it’s moving.- All objects want to remain motionless, - All objects want to remain motionless, but if a force moves them, then they but if a force moves them, then they want to continue moving in the same want to continue moving in the same direction at a constant speed.direction at a constant speed.


DistanceDistance

Total ground covered or traveled. A scalar.Total ground covered or traveled. A scalar. DisplacementDisplacement

As the crow flies - A As the crow flies - A straightstraight line between the line between the beginning and the end. Measured in cm, m, km. A beginning and the end. Measured in cm, m, km. A vectorvector

SpeedSpeed

Distance divided by time. 100 miles traveled in two Distance divided by time. 100 miles traveled in two hours average 50 mph.hours average 50 mph.

VelocityVelocity

Displacement divided by time. 100 meters south Displacement divided by time. 100 meters south divided by 10 seconds equal 10 meters per second in divided by 10 seconds equal 10 meters per second in the south direction.the south direction.


Speed, Velocity and AccelerationSpeed, Velocity and Acceleration - A sprinter running the 100 m in 10 sec has - A sprinter running the 100 m in 10 sec has

an average speed of 10 m/s or ~ 22 mph. an average speed of 10 m/s or ~ 22 mph. This average speed indicates that the This average speed indicates that the sprinter must have been going faster and sprinter must have been going faster and slower at times to average the 22.slower at times to average the 22.

- Velocity is a more precise description of - Velocity is a more precise description of speed - Giving it direction. Thus it includes speed - Giving it direction. Thus it includes both speed and direction - 20 mph due south.both speed and direction - 20 mph due south.

- The rate at which velocity changes is termed - The rate at which velocity changes is termed acceleration. It may be positive or negative.acceleration. It may be positive or negative.


GravityGravity

- It is constant and it accelerates falling - It is constant and it accelerates falling bodies at a rate of 32 feet per second bodies at a rate of 32 feet per second per second or 9.8 meters per second per second or 9.8 meters per second per second.per second.

- It affects performance because the - It affects performance because the effects of gravity change the further you effects of gravity change the further you are from the center or core of the earth.are from the center or core of the earth.

- Ex. Mexico vs Moscow distances - Ex. Mexico vs Moscow distances (elevations and equator).(elevations and equator).


Center of GravityCenter of Gravity- - The earth’s gravitational pull on the athlete is The earth’s gravitational pull on the athlete is concentrated at the athlete’s concentrated at the athlete’s center of gravitycenter of gravity..

- It represents the center of how the mass is - It represents the center of how the mass is distributed from head to toes. Muscle and bone distributed from head to toes. Muscle and bone are more dense and thus have more mass are more dense and thus have more mass squashed into the space they occupy and thus squashed into the space they occupy and thus the earth pulls more on those parts.the earth pulls more on those parts.

- Ex. Males higher cog then females (hips)- Ex. Males higher cog then females (hips)

- Cog changes as limbs move and can be - Cog changes as limbs move and can be outside the body.outside the body.


ForceForce

- A push or a pull that changes or - A push or a pull that changes or tends to change the state of motion tends to change the state of motion of an athlete or object.of an athlete or object.

Force vector - refers to when the Force vector - refers to when the directiondirection and and amountamount of force is of force is known.known.

Force Vectors - AdditionForce Vectors - Addition

+ =

Tip to Tail

+=

Parallelogram

Force Vectors - Force Vectors - SubtractionSubtraction

_ =+ _

+ =Tip to Tail

Force Vectors - Force Vectors - MultiplicationMultiplication

x =+

=Tip to Tail

2

ab

c

What is a+b+c and 2c-a+3b and

–c-b+a and a-b-c and –a-b-c?

How many vectors can you add?

MotionMotion

LinearLinear Rectilinear (skydiver, putt on level ground)Rectilinear (skydiver, putt on level ground) Curvilinear (parabolic trajectory, Curvilinear (parabolic trajectory,

cannonball)cannonball) Angular (Rotary)Angular (Rotary)

Rotates about an axis (wheels, spin dives, Rotates about an axis (wheels, spin dives, joints, curveballs)joints, curveballs)

GeneralGeneral Combination of linear and angular Combination of linear and angular

(sprinting)(sprinting)

Projectile MotionProjectile Motion

To increase the horizontal distance To increase the horizontal distance (range) of a projectile you need to (range) of a projectile you need to consider:consider: The velocity at releaseThe velocity at release The angle at releaseThe angle at release The height at releaseThe height at release

Factors Influencing Projectile Trajectory

Max

imum

hei

ght

(m)

Range (distance) (m)0 1 2 3 4 5 6 7 8 9 10 11

5

4

3

2

1

0

This scaled diagram shows the size and shape of trajectories for an object projected at 10 m/s at different angles.


Newton’s LawsNewton’s Laws- Law of Inertia - a body will remain at rest - Law of Inertia - a body will remain at rest or continue to move at a constant velocity or continue to move at a constant velocity unless acted upon by an external force.unless acted upon by an external force.

- Law of Acceleration - the acceleration of - Law of Acceleration - the acceleration of an object is directly proportional to the an object is directly proportional to the force causing it, it is in the same direction force causing it, it is in the same direction as the force and it is inversely proportional as the force and it is inversely proportional to its mass.to its mass.

- Law of Reaction - for every action there - Law of Reaction - for every action there exists an equal and opposite reaction.exists an equal and opposite reaction.

Chapter 3 - Getting a Chapter 3 - Getting a Move OnMove On

Action - ReactionAction - Reaction MomentumMomentum ImpulseImpulse WorkWork EnergyEnergy ReboundRebound FrictionFriction


Action - ReactionAction - ReactionThis again is referring to Newton’s third law This again is referring to Newton’s third law (Law of Reaction). (Law of Reaction).

Ex. Sprinter pushing against the blocks and the Ex. Sprinter pushing against the blocks and the earth pushing back on the attached block to earth pushing back on the attached block to propel the sprinter forward.propel the sprinter forward.

The force produced by the sprinter’s muscles The force produced by the sprinter’s muscles overcome inertia and she accelerates. This overcome inertia and she accelerates. This acceleration is proportional to how much force acceleration is proportional to how much force she applies the the time frame over which it is she applies the the time frame over which it is applied, and it is inversely proportional to her applied, and it is inversely proportional to her mass.mass.


MomentumMomentumA moving athlete/object is an example of mass on A moving athlete/object is an example of mass on the move. Because a certain amount of mass is the move. Because a certain amount of mass is moving we refer to this as the a/o moving we refer to this as the a/o momentummomentum. It . It describes the quantity of motion that occurs. To describes the quantity of motion that occurs. To increase momentum the a/o needs to increase increase momentum the a/o needs to increase either its mass or its velocity or both.either its mass or its velocity or both.

Important in sports that have collisions and impact Important in sports that have collisions and impact - football, bowling, billiards. Increase mass by - football, bowling, billiards. Increase mass by putting on muscle to increase power and speed.putting on muscle to increase power and speed.

Car accidents experts reconstruct crash scenes by Car accidents experts reconstruct crash scenes by determining which car had greater momentum.determining which car had greater momentum.

MomentumMomentum

Testing the new Armed Forces barriers...Testing the new Armed Forces barriers...

From time to time someone asks what the concrete From time to time someone asks what the concrete barriers are in front of controlled and secure barriers are in front of controlled and secure buildings. When told that the barriers will stop buildings. When told that the barriers will stop traffic, even trucks, from approaching the secure traffic, even trucks, from approaching the secure building I usually get a look of disbelief. Looking building I usually get a look of disbelief. Looking for some footage like this to prove the point, in for some footage like this to prove the point, in this test, the following parameters were used. this test, the following parameters were used. Read them and then watch the film.Read them and then watch the film.

Truck = 65,000 lbs.Truck = 65,000 lbs.Speed = 50 mphSpeed = 50 mphKinetic Energy = 5.5 MILLION ft. lbs.Kinetic Energy = 5.5 MILLION ft. lbs.Stopped in 24 INCHES!Stopped in 24 INCHES!

Truck VideoTruck Video


ImpulseImpulseTo accelerate or to produce movement, an athlete needs To accelerate or to produce movement, an athlete needs to produce muscular force and create momentum. This to produce muscular force and create momentum. This force always takes time to produce and we refer to the force always takes time to produce and we refer to the application of force over a certain amount of time as application of force over a certain amount of time as impulseimpulse..

Ex. Karate blow - Large force - short period of time. Ex. Karate blow - Large force - short period of time. Bones 40 times stronger than concrete.Bones 40 times stronger than concrete.

Javelin throw - large force - long period of time. Strength Javelin throw - large force - long period of time. Strength and flexibility are important.and flexibility are important.

High jump - large force - medium period of time. Not a High jump - large force - medium period of time. Not a full squat, but a quarter squat and rocking over the heel full squat, but a quarter squat and rocking over the heel and backwards lean increase the amount of time over and backwards lean increase the amount of time over which to produce force.which to produce force.


Conservation of Linear MomentumConservation of Linear Momentum

Total amount of linear momentum of Total amount of linear momentum of colliding bodies will be the same before colliding bodies will be the same before and after the collision.and after the collision.

If one body gains momentum then the If one body gains momentum then the other must lose momentum.other must lose momentum.

Collisions cannot create or dissipate linear Collisions cannot create or dissipate linear momentum but rather transfer it from momentum but rather transfer it from one object to another.one object to another.

m1v1 + mm1v1 + m22vv22 = (m = (m11 + m + m22) (v)) (v)

Conservation of Conservation of MomentumMomentum

In the absence of external forces, the total In the absence of external forces, the total momentum of a given system remains momentum of a given system remains constant.constant.

A 90 kg hockey player traveling with a velocity of 6 m/s collides head-on with an A 90 kg hockey player traveling with a velocity of 6 m/s collides head-on with an 80 kg player traveling a 7 m/s. If the two players entangle and continue 80 kg player traveling a 7 m/s. If the two players entangle and continue traveling together as a unit following the collision, what is their combined traveling together as a unit following the collision, what is their combined velocity?velocity?

Known: mKnown: m11= 90 kg m= 90 kg m22=80 kg v=80 kg v11= 6 m/s v= 6 m/s v22= -7 m/s= -7 m/s

m1v1 + mm1v1 + m22vv22 = (m = (m11 + m + m22) (v)) (v)

(90 kg) (6 m/s) + (80 kg) (-7 m/s) = (90 kg + 80 kg) (v)(90 kg) (6 m/s) + (80 kg) (-7 m/s) = (90 kg + 80 kg) (v)

540 kg m/s – 560 kg m/s = (170 kg) (v)540 kg m/s – 560 kg m/s = (170 kg) (v)

- 20 kg m/s = (170 kg) (v)- 20 kg m/s = (170 kg) (v)

v = 0.12 m/s in the direction of the 80 kg player’s original direction of v = 0.12 m/s in the direction of the 80 kg player’s original direction of travel travel


WorkWork

Mechanical work defined as force times Mechanical work defined as force times distance. Ex. Filling shelves, throwing distance. Ex. Filling shelves, throwing the javelin, ball slowed by turf, lifting the javelin, ball slowed by turf, lifting weights.weights.

Different from physiological work in that Different from physiological work in that for MW the object needs to move. A for MW the object needs to move. A static or isometric contraction would static or isometric contraction would involve PW but not MW. Unit is the involve PW but not MW. Unit is the Joule.Joule.


PowerPower

The rate at which work is done.The rate at which work is done.

It may be expressed as P = W/t or P = It may be expressed as P = W/t or P = F x VF x V

In the metric system unit for Power is In the metric system unit for Power is the wattthe watt

Which is equivalent to 1 joule/secondWhich is equivalent to 1 joule/second


EnergyEnergy

Defined as the capacity of an a/o to do Defined as the capacity of an a/o to do work. Mechanical energy has three work. Mechanical energy has three forms.forms.

Kinetic, Potential and Strain energy.Kinetic, Potential and Strain energy.

Kinetic - moving energy KE = ½ * m * vKinetic - moving energy KE = ½ * m * v22

Potential - location/position energy PE = Potential - location/position energy PE = m * g * hm * g * h

Strain - stored energyStrain - stored energy


Conservation of EnergyConservation of Energy

As a diver begins to fall towards water As a diver begins to fall towards water her potential energy is transformed her potential energy is transformed into kinetic energy.into kinetic energy.

A ball thrown into the air has both A ball thrown into the air has both kinetic and potential energy throughout kinetic and potential energy throughout its flight or parabolic trajectoryits flight or parabolic trajectory

Ex. Rib cage testing device for crash Ex. Rib cage testing device for crash dummies.dummies.


ReboundReboundWhen objects/bodies separate (move apart) after a When objects/bodies separate (move apart) after a collision or impact occurs.collision or impact occurs.

Angle of incidence and angle of reflection/rebound Angle of incidence and angle of reflection/rebound measured with respect to the vertical.measured with respect to the vertical.

Coefficient of elasticity/restitution refers to the Coefficient of elasticity/restitution refers to the degree (amount) of recoil/bounce that objects degree (amount) of recoil/bounce that objects have. The greater the bounce the greater the have. The greater the bounce the greater the coefficient (value between 0 and 1) with 0 coefficient (value between 0 and 1) with 0 signifying a completely inelastic object and 1 signifying a completely inelastic object and 1 signifying a completely elastic object.signifying a completely elastic object.

Angle of Angle of Reflection/ReboundReflection/Rebound

Incidence Rebound


ReboundRebound

Affected by temperature and Affected by temperature and rebounding surface. Heat causes rebounding surface. Heat causes balls to bounce more while artificial balls to bounce more while artificial turf also will cause a greater bounce.turf also will cause a greater bounce.


FrictionFriction

Force that occurs when an object Force that occurs when an object moves or tends to move while in moves or tends to move while in contact with another object.contact with another object.

Reduce - wax skis, curling, bowling Reduce - wax skis, curling, bowling laneslanes

Increase - rough gloves, cleatsIncrease - rough gloves, cleats

Mechanical Behavior of Bodies in Contact

What is friction?

• force acting over the area of contact between two surfaces

• direction is opposite of motion or motion tendency

• magnitude is the product of the coefficient of friction () and the

normal reaction force (R); F = R


FrictionFrictionThree types - Three types - static, sliding and rollingstatic, sliding and rolling..

StaticStatic - seen in resting bodies, resists initiation - seen in resting bodies, resists initiation of movement.of movement.

SlidingSliding - force that develops when two objects - force that develops when two objects are sliding past each other.are sliding past each other.

RollingRolling - when round object rolls past another. - when round object rolls past another.

Factors affecting friction: forces pressing two Factors affecting friction: forces pressing two surfaces together, nature (texture) of surfaces, surfaces together, nature (texture) of surfaces, actual contact area.actual contact area.


FrictionFrictionPressure = Force / AreaPressure = Force / Area

One box exerts greater pressure against the floor One box exerts greater pressure against the floor than the other, thus squashing the microscopic than the other, thus squashing the microscopic irregularities found even on the smoothest of irregularities found even on the smoothest of surfaces and by so doing it creates the same surfaces and by so doing it creates the same contact area as the other box.contact area as the other box.


StaticFm = sR

DynamicFk = kR

Applied external force

Fric

tion

For static bodies, friction is equal to the applied force.

For bodies in motion, friction is constant

and less than maximum static

friction.


Is it easier to push or pull a desk

across a room?

Pushing a desk

Pulling a desk

R = wt + Pv

R = wt - Pv

FrictionFriction

Coefficient of FrictionCoefficient of FrictionThe ratio of the force needed to overcome the The ratio of the force needed to overcome the

Friction, to the force holding the surface Friction, to the force holding the surface together is called the coefficient of frictiontogether is called the coefficient of friction

The coefficient is an experimentally derived The coefficient is an experimentally derived value that depends on the nature of the value that depends on the nature of the contact surfaces. The larger the coefficient contact surfaces. The larger the coefficient the more the surfaces cling to each other. A the more the surfaces cling to each other. A coefficient of 0 would indicate completely coefficient of 0 would indicate completely frictionless surfaces.frictionless surfaces.

Vectors and ScalarsVectors and Scalars

VectorsVectors - Two - Two quantities - quantities - Magnitude and Magnitude and DirectionDirection

* WeightWeight* VelocityVelocity* DisplacementDisplacement* AccelerationAcceleration* All forces - friction, All forces - friction,

drag, lift, buoyancy drag, lift, buoyancy etc.etc.

ScalarsScalars - Single - Single quantity - quantity - MagnitudeMagnitude

* massmass* areaarea* distancedistance* temperaturetemperature* speedspeed

FormulasFormulas

A= A= v/tv/t V= V= displacement/tdisplacement/t Speed = Speed = distance/tdistance/t Impulse = F * tImpulse = F * t Momentum = m * vMomentum = m * v Work = F * Work = F *

displacementdisplacement Power = Work / tPower = Work / t

Weight = m * gWeight = m * g PE = m * g * hPE = m * g * h KE = ½ * m * vKE = ½ * m * v22

TE = PE + KE + SETE = PE + KE + SE

Chapter 4 - Rocking and Chapter 4 - Rocking and RollingRolling

Angular motionAngular motion Lever SystemsLever Systems TorqueTorque Types of leversTypes of levers Angular velocityAngular velocity Inertia, Centripetal and Centrifugal Inertia, Centripetal and Centrifugal

ForceForce Rotary InertiaRotary Inertia Angular MomentumAngular Momentum


Angular motionAngular motion

Measured in degrees or Measured in degrees or revolutions, 360 degrees is equal revolutions, 360 degrees is equal to one full revolution, 180 is half, to one full revolution, 180 is half, 90 is one-quarter of a rev. and so 90 is one-quarter of a rev. and so on.on.

Also referred to as spin, rotation, Also referred to as spin, rotation, twist, swing, etc.twist, swing, etc.


Lever SystemsLever Systems

A lever is a simple machine that A lever is a simple machine that transmits and changes mechanical transmits and changes mechanical energy from one place to another.energy from one place to another.

AAlways, lways, RRead, ead, FFirstirst

Axis, Resistance, Force - What is Axis, Resistance, Force - What is in the middle will dictate the type in the middle will dictate the type of lever system (First, Second or of lever system (First, Second or Third Class).Third Class).


Angular MotionAngular Motion

Eccentric ForceEccentric Force – force applied a – force applied a certain distance away from cog of certain distance away from cog of object therefore causing rotationobject therefore causing rotation

Centric ForceCentric Force – force applied – force applied through the center of gravity of through the center of gravity of object creating linear motionobject creating linear motion

Force coupleForce couple – two equal and – two equal and opposite forces that cause rotationopposite forces that cause rotation


Torque Torque - A rotary, turning, or - A rotary, turning, or twisting effect produced by a force twisting effect produced by a force acting at a distance from the axis of acting at a distance from the axis of rotation. The initiation of rotation rotation. The initiation of rotation requires the application of torque.requires the application of torque.

Ex: torque wrench, dumbbell curl.Ex: torque wrench, dumbbell curl. Torque is equal to force multiplied Torque is equal to force multiplied

by the length of the force arm (the by the length of the force arm (the perpendicular distance between axis perpendicular distance between axis and point of force).and point of force).


Torque Torque

A sum of torques may result in no A sum of torques may result in no motion (isometric contraction), motion (isometric contraction), angular motion (dumbbell curl) or angular motion (dumbbell curl) or linear motion (rowing boat).linear motion (rowing boat).

The perpendicular distance from The perpendicular distance from where the force is applied to the where the force is applied to the axis of rotation is termed the torque axis of rotation is termed the torque arm, moment arm and force arm - arm, moment arm and force arm - all meaning the same thing.all meaning the same thing.

Torque videoTorque video


Types of leversTypes of levers

First Class - triceps extension, leg First Class - triceps extension, leg presspress

Second Class - calf raises, rowingSecond Class - calf raises, rowingFavors the output of force at the Favors the output of force at the

expense of speed and range of motion.expense of speed and range of motion.

Third Class - biceps curlThird Class - biceps curlAlways move the resistance through a Always move the resistance through a

larger range of movement than that larger range of movement than that moved by the force.moved by the force.


Mechanical AdvantageMechanical Advantage

It is a measure of the efficiency of a It is a measure of the efficiency of a machine or a lever system. In machine or a lever system. In other words what is the machine’s other words what is the machine’s ability to magnify force or another ability to magnify force or another way of expressing it is “what is the way of expressing it is “what is the output of the machine relative to output of the machine relative to its input”its input”

MA= FA divided by RA (FA/RA)MA= FA divided by RA (FA/RA)


Mechanical AdvantageMechanical AdvantageNote that in third class levers the FA is Note that in third class levers the FA is

always less than the RA so MA is less than always less than the RA so MA is less than 1.0, which is low mechanical advantage. 1.0, which is low mechanical advantage. Second class levers on the other hand are Second class levers on the other hand are more efficient with MA greater than 1.0. more efficient with MA greater than 1.0.

We make adjustments to increase our We make adjustments to increase our mechanical advantage by using a crowbar mechanical advantage by using a crowbar in prying we increase the FA thus in prying we increase the FA thus increasing the mechanical advantage or increasing the mechanical advantage or carrying a heavy load close to our bodies carrying a heavy load close to our bodies to reduce the RA and thus increase the to reduce the RA and thus increase the mechanical advantage.mechanical advantage.


Angular velocityAngular velocity The rate of spin of an athlete or object. The rate of spin of an athlete or object.

The rate of swing of a club or bat. The rate of swing of a club or bat. However as the distance from the axis However as the distance from the axis

of rotation to the end of the bat of rotation to the end of the bat increase so does the LINEAR velocity increase so does the LINEAR velocity of the end of the bat. Therefore Linear of the end of the bat. Therefore Linear velocity of a rotating segment is the velocity of a rotating segment is the product of the angular velocity and the product of the angular velocity and the radius (or distance from axis).radius (or distance from axis).

Relationship of Linear Relationship of Linear and Angular velocitiesand Angular velocities

Lin. Vel = Ang. Lin. Vel = Ang. Vel * radius Vel * radius

How fast a ball How fast a ball comes off the bat comes off the bat (lin vel) is equal to (lin vel) is equal to how fast you how fast you swing (ang vel) swing (ang vel) the bat times the the bat times the length of the bat length of the bat (radius)(radius)


Centripetal and Centrifugal Centripetal and Centrifugal ForceForce

Centripetal force is that force used Centripetal force is that force used to maintain an object moving to maintain an object moving around a circular path while around a circular path while centrifugal is the equal and centrifugal is the equal and opposite reaction to this centripetal opposite reaction to this centripetal force. While this force is affected force. While this force is affected by both the angular velocity and by both the angular velocity and the mass of the object, it is the the mass of the object, it is the angular velocity which has a angular velocity which has a greater impact.greater impact.


Rotary InertiaRotary Inertia The resistance to rotate or follow a circular The resistance to rotate or follow a circular

path.path. I = I = ΣΣ m * r m * r22

Again the a/o wants to remain at rest or Again the a/o wants to remain at rest or continue moving at a constant angular continue moving at a constant angular speed.speed.

To increase the rotary inertia of an object To increase the rotary inertia of an object you increase BOTH the mass of the a/o and you increase BOTH the mass of the a/o and how far this mass is from the axis of how far this mass is from the axis of rotation.rotation.


Angular MomentumAngular Momentum Much like linear momentum, Much like linear momentum,

angular momentum refers to the angular momentum refers to the product of the angular velocity product of the angular velocity times the rotational inertia of the times the rotational inertia of the a/o.a/o.

FormulasFormulas

FFcc = (m * v = (m * v22)/ r)/ r

v is tangential v is tangential velocity and r is velocity and r is radius of rotationradius of rotation

FFcc= m * r * = m * r * ωω22

ωω = angular velocity = angular velocity T = I * T = I * αα

αα = angular = angular accelerationacceleration

Angular velocity =Angular velocity =

ang. displ / tang. displ / t Angular Angular

acceleration = acceleration = ang. Vel. / tang. Vel. / t

Torque = F * dTorque = F * d Angular momentum Angular momentum

= Rotary Inertia * = Rotary Inertia * ang velang vel

Chapter 5 - Don’t be a Chapter 5 - Don’t be a PushoverPushover

Equilibrium, balance and stabilityEquilibrium, balance and stability Linear stabilityLinear stability Rotary stabilityRotary stability


Equilibrium or balanceEquilibrium or balance implies implies coordination and controlcoordination and control

StabilityStability relates to how much relates to how much resistance a/o put up against having resistance a/o put up against having their equilibrium disturbed. The their equilibrium disturbed. The more stable the a/o the more more stable the a/o the more resistance the athlete generates resistance the athlete generates against disruptive forcesagainst disruptive forces


Equilibrium, balance and Equilibrium, balance and stabilitystability

StableStable Unstable Unstable NeutralNeutral


Linear stabilityLinear stabilityDefined as the resistance against being moved Defined as the resistance against being moved in a particular direction and resistance against in a particular direction and resistance against being stopped or having its direction changed being stopped or having its direction changed once it is moving.once it is moving.

While at rest an a/o’s linear stability are While at rest an a/o’s linear stability are govern by its mass and the frictional forces govern by its mass and the frictional forces occurring between the a/o and the supporting occurring between the a/o and the supporting surfaces.surfaces.

When in motion the a/o’s linear stability is When in motion the a/o’s linear stability is directly related to momentum.directly related to momentum.


Rotary stabilityRotary stabilityDefined as resistance to being tipped over or Defined as resistance to being tipped over or upended. Six factors that would increase upended. Six factors that would increase stability:stability:

1) increase the base of support1) increase the base of support

2) the a/o’s line of gravity falls within the bos2) the a/o’s line of gravity falls within the bos

3) lowering the center of gravity3) lowering the center of gravity

4) increase body mass4) increase body mass

5) base of support extends toward the oncoming 5) base of support extends toward the oncoming forceforce

6) line of gravity shifts toward an oncoming force6) line of gravity shifts toward an oncoming force

Chapter 6 - Going with Chapter 6 - Going with the Flowthe Flow

Hydrostatic PressureHydrostatic Pressure BuoyancyBuoyancy DragDrag LiftLift


Hydrostatic PressureHydrostatic Pressure

Force exerted by a fluid like air or Force exerted by a fluid like air or water.water.

Ex. Blankets layered on you, sea level Ex. Blankets layered on you, sea level = more blankets of atmosphere= more blankets of atmosphere

- Water is more dense than air thus - Water is more dense than air thus weighs more, therefore pressure weighs more, therefore pressure exerted by water increases with depth exerted by water increases with depth much faster than in air.much faster than in air.


BuoyancyBuoyancy

- - Acts upward fighting gravityActs upward fighting gravity

- Pressure increases with depth- Pressure increases with depth

- Water presses on the athlete from all directions- Water presses on the athlete from all directions

- Push from below (greater pressure) is greater - Push from below (greater pressure) is greater than sides or abovethan sides or above

- This force from below is called buoyancy- This force from below is called buoyancy

- Helium or hot air are also lifted by a buoyant - Helium or hot air are also lifted by a buoyant force as a result of being lighter gases than force as a result of being lighter gases than normal air.normal air.


Center of BuoyancyCenter of Buoyancy

- The place where the buoyant force - The place where the buoyant force concentrates its upward push on the concentrates its upward push on the athlete’s body.athlete’s body.

- Lungs and torso take up more space - Lungs and torso take up more space and weigh less compared to the legs.and weigh less compared to the legs.

- Therefore the c of b is generally just - Therefore the c of b is generally just below the rib cage, thus causing a below the rib cage, thus causing a torque which results in a tilted floating torque which results in a tilted floating position.position.


To float or not to float that is the questionTo float or not to float that is the question

- An a/o in the water has essential two forces - An a/o in the water has essential two forces acting upon it. Its weight will be pulling it acting upon it. Its weight will be pulling it down while the buoyant force will be pulling it down while the buoyant force will be pulling it up. Depending on which vector is greater - up. Depending on which vector is greater - the a/o will float or sink.the a/o will float or sink.

- Specific gravity is equal to the ratio between - Specific gravity is equal to the ratio between the density of the a/o and the density of water. the density of the a/o and the density of water. If the spec. grav. is greater than one the a/o If the spec. grav. is greater than one the a/o will sink, if it is less than one than it will float.will sink, if it is less than one than it will float.


To float or not to float that is the To float or not to float that is the questionquestion

- Other factors that may affect your - Other factors that may affect your ability to float:ability to float:

+ gender+ gender

+ age+ age

+ lung capacity+ lung capacity

+ water temperature and density+ water temperature and density


DragDrag

Varies according to:Varies according to:Type of fluid (water or air)Type of fluid (water or air)

Density and viscosity of fluid (sticky and Density and viscosity of fluid (sticky and clingy)clingy)

Shape and size of athleteShape and size of athlete

But, most importantly it varies or it is But, most importantly it varies or it is most influenced by the relative velocity most influenced by the relative velocity of object and fluid.of object and fluid.


DragDrag

Three types of drag are surface, form Three types of drag are surface, form and wave drag.and wave drag.

Surface drag is also called viscous drag Surface drag is also called viscous drag or skin friction and the amount of or skin friction and the amount of surface drag is determined by the surface drag is determined by the relative motion of object and fluid, the relative motion of object and fluid, the area of surface exposed to the flow, the area of surface exposed to the flow, the roughness of the object’s surface, and roughness of the object’s surface, and the fluid viscosity.the fluid viscosity.


DragDrag

Form drag is also called shape drag or Form drag is also called shape drag or pressure drag and the amount of form drag pressure drag and the amount of form drag is determined by the relative motion of is determined by the relative motion of object and fluid, the pressure differential object and fluid, the pressure differential between the leading and trailing edges of between the leading and trailing edges of the object, and the amount of surface acting the object, and the amount of surface acting at right angles to the flow.at right angles to the flow.

Streamlining refers to tapering both front and Streamlining refers to tapering both front and trailing edges so as to minimize the surface area trailing edges so as to minimize the surface area hitting the flow on the front and the turbulent hitting the flow on the front and the turbulent area on the back.area on the back.


DragDrag

Wave drag occurs at the interface Wave drag occurs at the interface between water and air. The amount between water and air. The amount of wave drag is determined by the of wave drag is determined by the relative velocity with which the relative velocity with which the object and wave meet, the surface object and wave meet, the surface area of the object acting at right area of the object acting at right angles to the wave, and the fluid angles to the wave, and the fluid viscosity.viscosity.


LiftLift

A force that acts perpendicular to the A force that acts perpendicular to the direction of motion.direction of motion.

Three ways of developing lift are Three ways of developing lift are through an airfoil shaped object, through an airfoil shaped object, modifying the angle of attack and modifying the angle of attack and through spin (lift caused by spinning through spin (lift caused by spinning balls is referred to as the Magnus balls is referred to as the Magnus Effect).Effect).


Lift and Magnus EffectLift and Magnus Effect

A spinning object traveling through A spinning object traveling through the air builds up high pressure on the air builds up high pressure on the side spinning into the airflow. the side spinning into the airflow. Low pressure occurs on the side Low pressure occurs on the side spinning with the airflow. The ball is spinning with the airflow. The ball is deflected from high pressure to low deflected from high pressure to low pressure.pressure.

Chapter 7 - Analyzing Chapter 7 - Analyzing Sport SkillsSport Skills

ObjectivesObjectives Special CharacteristicsSpecial Characteristics Elite performancesElite performances Divide into phasesDivide into phases Divide into key elementsDivide into key elements Mechanical reasons Mechanical reasons


Determine the Objectives of the SkillDetermine the Objectives of the Skill

- Rules of the sport- Rules of the sport

Ex. Throwing the discus for distance and also Ex. Throwing the discus for distance and also for accuracy (land on selected sector) - speed for accuracy (land on selected sector) - speed of release, spin created, trajectory, stability to of release, spin created, trajectory, stability to avoid foul. Volleyball - jump, spike, ball avoid foul. Volleyball - jump, spike, ball trajectory, touch net.trajectory, touch net.

Wt. Lifting - strength, balance, stability.Wt. Lifting - strength, balance, stability.

- Be aware of ALL objectives required for the - Be aware of ALL objectives required for the skill.skill.


Special CharacteristicsSpecial CharacteristicsSport skills can be divided into different types Sport skills can be divided into different types based on a) based on a) mannermanner and b) and b) conditioncondition..

A) Manner - skill performed once (nonrepetitive or A) Manner - skill performed once (nonrepetitive or discrete) or repeat sequentially (repetitive or cyclic).discrete) or repeat sequentially (repetitive or cyclic).

B) Condition - Predictable environment (closed skills) no B) Condition - Predictable environment (closed skills) no need to make quick decisions because of sudden changeneed to make quick decisions because of sudden change

Clean and jerk, synchronized swimming - easier practiceClean and jerk, synchronized swimming - easier practice

Unpredictable environment (open skills) - presence of Unpredictable environment (open skills) - presence of opposition or env. Cond. (wind, waves, rain, sun or field) opposition or env. Cond. (wind, waves, rain, sun or field) Teach it by making it predictable and repetitive first, Teach it by making it predictable and repetitive first, then add the opposition.then add the opposition.


Study Top-Flight Performances of the Study Top-Flight Performances of the SkillSkill

- Getting a picture of speed, rhythm, - Getting a picture of speed, rhythm, power, body positions, etc.power, body positions, etc.

- Tape it from various angles and watch it - Tape it from various angles and watch it in slow motion.in slow motion.

- Although body types differ, many - Although body types differ, many common features exist. Ex. Golfers common features exist. Ex. Golfers shifting their weight and rotating their shifting their weight and rotating their hipships


Divide the skill into phasesDivide the skill into phases- - Makes your job of looking for errors easier. Not Makes your job of looking for errors easier. Not confused by watching too much at the same time.confused by watching too much at the same time.

- Four common phases are: Preparatory, Wind-up, Force - Four common phases are: Preparatory, Wind-up, Force and Follow-through.and Follow-through.

PrepPrep - early mistakes will manifest themselves in the - early mistakes will manifest themselves in the resultant outcome.resultant outcome.

Wind-upWind-up - muscle stretch, force over a long distance and - muscle stretch, force over a long distance and timetime

ForceForce - apply it in the right sequence and for the rt amt of - apply it in the right sequence and for the rt amt of timetime

Follow-throughFollow-through - maintain balance and continuity of - maintain balance and continuity of motion.motion.


Divide into key elementsDivide into key elementsOnce you’ve divided the skill into important Once you’ve divided the skill into important phases, you can direct your attention phases, you can direct your attention towards dividing each phase into towards dividing each phase into key key elementselements. .

A key element are distinct actions that are A key element are distinct actions that are essential to the success of each phase in the essential to the success of each phase in the skill. Key elements are essential in good skill. Key elements are essential in good technique and contribute mechanically technique and contribute mechanically toward the success of the skill.toward the success of the skill.


Mechanical reasonsMechanical reasons By far the most important step in analyzing By far the most important step in analyzing

a skill. This is what differentiates you a skill. This is what differentiates you from a coach that has learned his trade from a coach that has learned his trade simply from being involved in the sport.simply from being involved in the sport.

Mechanics after all are the foundation of all Mechanics after all are the foundation of all sport techniques. These techniques are sport techniques. These techniques are founded on mechanical principles/laws. founded on mechanical principles/laws. Thus after choosing the key elements it is Thus after choosing the key elements it is important to understand the mechanical important to understand the mechanical purposes behind each element.purposes behind each element.


Elite IdiosyncrasiesElite Idiosyncrasies

Look for basic techniques that top athletes Look for basic techniques that top athletes use.use.

As you improve your analytical skill you will As you improve your analytical skill you will begin to disregard some actions elite begin to disregard some actions elite athletes use that are personal athletes use that are personal idiosyncrasies and have no mechanical idiosyncrasies and have no mechanical value (ie - Jordan sticking his tongue out!)value (ie - Jordan sticking his tongue out!)

Remember to take into account maturity, Remember to take into account maturity, strength, flexibility, and endurance of a strength, flexibility, and endurance of a young immature athlete or novice.young immature athlete or novice.

Chapter 8 - Identifying Chapter 8 - Identifying and Correcting Errorsand Correcting Errors

Observe complete skillObserve complete skill Analyze each phase and its key Analyze each phase and its key

elementelement Use sport mechanics in your analysisUse sport mechanics in your analysis Select errors to be correctedSelect errors to be corrected Decide on appropriate methodsDecide on appropriate methods


Observe complete skillObserve complete skillObserve and video record your athlete performing the Observe and video record your athlete performing the

skill from different positions. Front, back, 90 skill from different positions. Front, back, 90 degrees, left and right. Elements that are hidden degrees, left and right. Elements that are hidden from one point of view may be clear and from one point of view may be clear and unobstructed from another. Be careful if/when unobstructed from another. Be careful if/when filming from the front - SAFETY comes first!!filming from the front - SAFETY comes first!!

Choose a site with no or little distractions to you or Choose a site with no or little distractions to you or your athlete, this way your athlete can concentrate your athlete, this way your athlete can concentrate on the skill.on the skill.

Make certain the athlete appears as large as possible Make certain the athlete appears as large as possible within the field of view of the camera without within the field of view of the camera without cutting off any of the action.cutting off any of the action.


Observe complete skillObserve complete skillMake certain your athlete has a proper warm-up prior Make certain your athlete has a proper warm-up prior

to executing the skill forcefully or maximally. This to executing the skill forcefully or maximally. This will allow you to observe the athlete’s performance will allow you to observe the athlete’s performance and get an overall impression.and get an overall impression.

Keep the athlete enthuse by giving some positive Keep the athlete enthuse by giving some positive feedback but refrain from offering instruction after feedback but refrain from offering instruction after or during each trial. Your athlete should not strive or during each trial. Your athlete should not strive to impress you but rather give you a true measure to impress you but rather give you a true measure of his/her performance.of his/her performance.

Use visual and auditory signals to gage the quality of Use visual and auditory signals to gage the quality of the performance (loud foot slap on trip jump, or bad the performance (loud foot slap on trip jump, or bad v-ball set.v-ball set.


Analyze each phase and its key Analyze each phase and its key elementselements

Start with the result - lack of spiral or Start with the result - lack of spiral or distance on a punt.distance on a punt.

Observe each phase of the skill in sequenceObserve each phase of the skill in sequence

Critically observe the first phase Critically observe the first phase (preparation), then shift your attention to (preparation), then shift your attention to the second phase (acceleration) and finish the second phase (acceleration) and finish with the follow-through.with the follow-through.


Use sport mechanics in your Use sport mechanics in your analysisanalysis

Ask yourself these questions:Ask yourself these questions:Does your athlete have optimal stability when Does your athlete have optimal stability when

applying or receiving force?applying or receiving force?

Is your athlete using all the muscles that make a Is your athlete using all the muscles that make a contribution to the skill?contribution to the skill?

Is your athlete applying force with the muscles in the Is your athlete applying force with the muscles in the correct sequence?correct sequence?

Is your athlete applying the right amount of Is your athlete applying the right amount of muscular force over the appropriate time frame?muscular force over the appropriate time frame?


Use sport mechanics in your Use sport mechanics in your analysisanalysis

Ask yourself these questions:Ask yourself these questions:Is your athlete applying force in the correct Is your athlete applying force in the correct

direction?direction?

Is your athlete correctly applying torque and Is your athlete correctly applying torque and momentum transfer?momentum transfer?

Is your athlete decreasing rotary resistance to spin Is your athlete decreasing rotary resistance to spin faster and increasing rotary resistance to spin faster and increasing rotary resistance to spin slower?slower?


Select errors to be correctedSelect errors to be corrected

After analyzing each phase and the After analyzing each phase and the key elements associated with each key elements associated with each phase, find errors to correct.phase, find errors to correct.

Rank each error in accordance to its Rank each error in accordance to its importance.importance.

Knes 300 - Principles of Human Movement Course Objectives Course Objectives 1) Learn about the...

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