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Home , Biomechanics, Kinematics, Kinetics (physics), Lever, Speed

• Biomechanics - study of the as it relates to the functional and anatomical analysis of biological Chapter 3 systems and especially humans Basic Biomechanical Factors & – Necessary to study the body’s mechanical characteristics & principles to understand Concepts its movements Manual of Structural R.T. Floyd, EdD, ATC, CSCS

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Biomechanics Biomechanics

• Mechanics - study of physical • - study of systems that are in a actions of constant state of , whether at rest with no motion or moving at a constant • Mechanics is divided into without – Statics – Statics involves all forces acting on the – body being in balance resulting in the body being in equilibrium

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Biomechanics Biomechanics

• Dynamics - study of systems in motion • & with acceleration – Kinematics - description of motion and – A system in acceleration is unbalanced includes consideration of , due to unequal forces acting on the body , velocity, acceleration, and factors of a system‘s motion – Kinetics - study of forces associated with the motion of a body

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1 Types of found in the body Types of machines found in the body

• • Machines in four ways – Load/effort or load divided by effort – balance multiple forces – Ideally using a relatively small , or effort to move a much greater resistance – enhance force in an attempt to reduce total • Musculoskeletal system may be thought of as force needed to overcome a resistance a series of simple machines – enhance range of motion & of – Machines - used to increase mechanical movement so that resistance may be advantage moved further or faster than applied force – Consider mechanical aspect of each component in analysis with respect to components’ -like – alter resulting direction of the applied force function

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Types of machines found in the body

• Musculoskeletel system arrangement • Humans moves through a system of provides for 3 types of machines in producing levers movement – Levers (most common) • Levers cannot be changed, but they can – Wheel-axles be utilized more efficiently – Pulleys – - a rigid bar that turns about an axis • Machine types not found in the body of or a fulcrum – – – axis - point of rotation about which lever – moves

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Levers Levers

• Levers rotate about an axis as a result • Resistance can vary from maximal to of force (effort, E) being applied to minimal cause its movement against a – May be only the or of body resistance or weight segment • In the body • All lever systems have each of these – bones represent the bars three components in one of three – joints are the possible arrangements – muscles contract to apply force

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2 Levers Levers

• Three points determine type of lever & • 1st class lever – axis (A) between for which kind of motion it is best suited force (F) & resistance (R) – Axis (A) - fulcrum - the point of rotation • 2nd class lever – resistance (R) – Point (F) of force application (usually between axis (A) & force (F) muscle insertion) - effort • 3rd class lever – force (F) – Point (R) of resistance application (center between axis (A) & resistance of of lever) or (location of an (R) external resistance)

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Levers Levers • FAR | Force Arm || Resistance Arm | 1st F R • The mechanical advantage of levers may be A determined using the following equations: Mechanical advantage = • ARF | Resistance Arm | | Force Arm | Resistance 2nd R F Force or A Mechanical advantage = • AFR | Force Arm | | Resistance Arm | Length of force arm 3rd Length of resistance arm F R A Manual of Manual of Structural Kinesiology Basic Biomechanical Factors & Concepts 3-15 Structural Kinesiology Basic Biomechanical Factors & Concepts 3-16

First-class Levers First-class Levers

• Produce balanced movements when • Head balanced on neck in axis is midway between force & flexing/extending resistance (e.g., seesaw) • Agonist & antagonist muscle groups • Produce speed & range of motion are contracting simultaneously on when axis is close to force, (triceps either side of a joint axis in elbow extension) – agonist produces force while • Produce force motion when axis is antagonist supplies resistance close to resistance (crowbar)

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3 First-class Levers First-class Levers

• Elbow extension in triceps applying • Force is applied where muscle inserts in force to olecranon (F) in extending the , not in belly of muscle non-supported forearm (R) at the – Ex. in elbow extension with shoulder fully elbow (A) flexed & arm beside the ear, the triceps applies force to the olecranon of ulna behind the axis of elbow joint – As the applied force exceeds the amount of forearm resistance, the elbow extends

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First-class Levers -class Levers

– Change example by placing the hand on • Produces force movements, since a the floor (as in a push-up) to push the body large resistance can be moved by a away from the floor, the same muscle relatively small force at this joint now changes the lever to – Wheelbarrow 2nd class due to the axis being at the hand – and the resistance is body weight at the – Loosening a lug nut elbow joint – Raising the body up on the toes

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Second-class Levers Third-class Levers

– Plantar flexion of foot to raise the • Produce speed & range-of-motion body up on the toes where ball (A) movements of the foot serves as the axis as • Most common in human body ankle plantar flexors apply force to • Requires a great deal of force to move the calcaneus (F) to lift the even a small resistance resistance of the body at the tibial – Paddling a boat articulation (R) with the foot – Shoveling - application of lifting force to a • Relatively few 2 nd class levers in shovel handle with lower hand while upper hand on shovel handle serves as axis of body rotation

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4 Third-class Levers Third-class Levers

– Biceps brachii in elbow flexion • Brachialis - true 3 rd class leverage Using the elbow joint (A) as the – pulls on ulna just below elbow axis, the biceps brachii applies – pull is direct & true since ulna cannot rotate force at its insertion on radial • Biceps brachii supinates forearm as it flexes tuberosity (F) to rotate forearm so its 3 rd class leverage applies to flexion only up, with its center of gravity (R) • Other examples serving as the point of – hamstrings contracting to flex leg at knee while in a resistance application standing – using iliopsoas to flex thigh at hip

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Factors in use of anatomical levers and length of lever arms

• Anatomical leverage system can be • Torque – ( of force) the turning used to gain a mechanical advantage effect of an eccentric force • Improve simple or complex physical • Eccentric force - force applied in a movements direction not in line with the center of rotation of an object with a fixed axis • Some habitually use human levers – In objects without a fixed axis it is an properly applied force that is not in line with object's • Some develop habits of improperly center of gravity using human levers • For rotation to occur an eccentric force must be applied Manual of Manual of Structural Kinesiology Basic Biomechanical Factors & Concepts 3-27 Structural Kinesiology Basic Biomechanical Factors & Concepts 3-28

Torque and length of lever arms Torque and length of lever arms

• In humans, contracting muscle applies • Force arm - perpendicular an eccentric force (not to be confused between location of force application & with eccentric contraction) to bone upon axis which it attaches & causes the bone to – a.k.a. moment arm or torque arm rotate about an axis at the joint – shortest distance from axis of rotation to • Amount of torque is determined by the line of action of the force multiplying amount of force ( force – the greater the distance of force arm, the magnitude ) by force arm more torque produced by the force

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5 Torque and length of lever arms Torque and length of lever arms

• Often, we purposely increase force arm • Inverse relationship between length of length in order to increase torque so the two lever arms that we can more easily move a – Between force & force arm relatively large resistance (increasing – Between resistance & resistance arm our leverage) – The longer the force arm, the less force required to move the lever if the resistance • Resistance arm - distance between the & resistance arm remain constant axis and the point of resistance – Shortening the resistance arm allows a application greater resistance to be moved if force & force arm remain constant

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Torque and length of lever arms Torque and length of lever arms

• Proportional relationship between force • Even slight variations components & resistance components in the location of the – If either of the resistance components force and resistance increase, there must be an increase in one are important in or both of force components determining the – Greater resistance or resistance arm effective force of the requires greater force or longer force arm muscle – Greater force or force arm allows a greater amount of resistance to be moved or a longer resistance arm to be used

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Torque and length of lever arms Torque and length of lever arms

Second class levers First class levers A, Placing the resistance halfway A, If the force arm & resistance arm between the axis & the point of force are equal in length, a force equal to application provides a MA of 2; the resistance is required to balance it; B, Moving the resistance closer to B, As the force arm becomes longer, a the axis increases the MA, but decreasing amount of force is required decreases the distance that the to move a relatively larger resistance; resistance is moved; C, As the force arm becomes shorter, C, the closer the resistance is an increasing amount of force is positioned to the point of force required to move a relatively smaller application the less of a MA, but the resistance greater the distance it is moved

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6 Torque and length of lever arms Torque and length of lever arms EXAMPLE: biceps curl A 0.05 meter F x FA = R x RA Third class levers increase in (force) x (force arm) = (resistance) x (resistance arm) A, a force greater than the resistance, insertion F x 0.1 meters = 45 newtons x 0.25 meters results in a regardless of the point of force F = 112.5 newtons application, is required due to the substantial reduction in Increase insertion by 0.05 meters resistance arm always being longer; the force F x 0.15 meters = 45 newtons x 0.25 meters B, Moving the point of force application necessary to closer to the axis increases the range move the F x 0.15 meters = 11.25 -meters of motion & speed; resistance F = 75 newtons C, Moving the point of force application | RA = 0.25 meters ||0.1 m| | RA = 0.25 meters || 0.15m | closer to the resistance decreases the force needed R F R F A A Manual of Manual of Structural Kinesiology Basic Biomechanical Factors & Concepts 3-37 Structural Kinesiology Basic Biomechanical Factors & Concepts 3-38

Torque and length of lever arms Torque and length of lever arms EXAMPLE: biceps curl EXAMPLE: biceps curl F x FA = R x RA A 0.05 meter F x FA = R x RA reduction in (force) x (force arm) = (resistance) x (resistance arm) Reducing (force) x (force arm) = (resistance) x (resistance arm) resistance F x 0.1 meters = 45 newtons x 0.25 meters resistance F x 0.1 meters = 45 newtons x 0.25 meters arm can F = 112.5 newtons reduces the reduce the amount of F = 112.5 newtons force Decrease resistance arm by 0.05 meters force Decrease resistance by 1 Newton necessary to F x 0.1 meters = 45 newtons x 0.2 meters needed to F x 0.1 meters = 44 newtons x 0.25 meter move the F x 0.1 meters = 9 newton-meters move the resistance lever F x 0.1 meters = 11 newton-meters F = 90 newtons F = 110 newtons | RA = 0.25 meters || 0.1m | | RA = 0.2 meters || 0.1m | | RA = 0.25 meters ||0.1 m| | RA = 0.25 meters ||0.1 m| F R F R R F R F A A A A Manual of Manual of Structural Kinesiology Basic Biomechanical Factors & Concepts 3-39 Structural Kinesiology Basic Biomechanical Factors & Concepts 3-40

Torque and length of lever arms Torque and length of lever arms

• Human leverage system is built for • Human leverage for sport skills requires speed & range of movement at expense several levers of force – throwing a ball involves levers at shoulder, • Short force arms & long resistance arms elbow & wrist joints require great muscular strength to • The longer the lever, the more effective produce movement it is in imparting velocity • Ex. biceps & triceps attachments – A tennis player can hit a tennis ball harder – biceps force arm is 1 to 2 inches with a straight-arm drive than with a bent elbow because the lever (including the – triceps force arm less than 1 inch racket) is longer & moves at a faster speed

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7 Torque and length of lever arms Torque and length of lever arms

• Long levers produce • For quickness, it is desirable to have a more linear force and short lever arm thus better performance – baseball catcher brings his hand back to in some sports such as his ear to secure a quick throw baseball, hockey, golf, – sprinter shortens his knee lever through field hockey, etc. flexion that he almost catches his spikes in his gluteal muscles

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Wheels and axles Wheels and axles

• Used primarily to enhance range of • Center of the wheel & the axle both motion & speed of movement in the correspond to the fulcrum musculoskeletal system • Both the radius of the wheel & the – function essentially as a form of a lever radius of the axle correspond to the • When either the wheel or axle turn, the force arms other must turn as well – Both complete one turn at the same time

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Wheels and axles Wheels and axles

• If the wheel radius is greater than the – calculate mechanical advantage of a radius of the axle, then, due to the wheel & axle by considering the longer force arm, the wheel has a radius of the wheel over the axle mechanical advantage over the axle – a relatively smaller force may be applied to the wheel to move a relatively greater Mechanical radius of the wheel resistance applied to the axle advantage = radius of the axle – if the radius of the wheel is 5 the radius of the axle, then the wheel has a 5 to 1 mechanical advantage over the axle

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8 Wheels and axles Wheels and axles

• If application of force is reversed and – Calculate the mechanical advantage applied to the axle, then the mechanical for this example by considering the advantage results from the wheel radius of the wheel over the axle turning a greater distance & speed – if the radius of the wheel is 5 times the Mechanical radius of the axle radius of the axle, then outside of the advantage = radius of the wheel wheel will turn at a speed 5 times that of the axle – the distance that the outside of the wheel turns will be 5 times that of the outside of the axle Manual of Manual of Structural Kinesiology Basic Biomechanical Factors & Concepts 3-49 Structural Kinesiology Basic Biomechanical Factors & Concepts 3-50

Wheels and axles Pulleys

• Ex. resulting in greater range of • Single pulleys function to motion & speed is with upper change effective direction of extremity in internal rotators force application attaching to humerus – Mechanical advantage = 1 – humerus acts as the axle • Pulleys may be combined to – hand & wrist are located at the outside of the wheel form compound pulleys to when elbow is flexed 90 degrees increase mechanical advantage – with minimal humerus rotation, the hand & wrist – Each additional rope increases travel a great distance mechanical advantage by 1 – allows us significantly increase the speed at which we can throw objects

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Pulleys Laws of motion and physical activities

• Ex. lateral malleolus acting as a • Body motion is produced or started by around which of some action of muscular system peroneus longus runs • Motion cannot occur without a force – As peroneus longus contracts, it pulls toward it belly (toward the • Muscular system is source of force in knee) humans – Using the lateral malleolus as a • Two types of motion pulley, force is transmitted to plantar aspect of foot resulting in – eversion/plantarflexion – angular motion

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9 Laws of motion and physical activities Laws of motion and physical activities

• Linear motion (translatory motion) - • Angular motion (rotary motion) - rotation motion along a line around an axis – rectilinear motion - motion along a straight – In the body, the axis of rotation is provided line by the various joints – curvilinear motion - motion along a curved • Linear & angular motion are related line – angular motion of the joints produces the • Linear displacement - distance that a linear motion of walking system moves in a straight line

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Laws of motion and physical activities Laws of motion and physical activities

• Sports ex. - cumulative angular motion • Displacement - actual distance that the of the joints imparts linear motion to a object has been displaced from its thrown object (ball, shot) or to an object original point of reference struck with an instrument (bat, racket) • Distance - actual sum length of measurement traveled – object may have traveled a distance of 10 meters along a linear path in two or more directions but only be displaced from its original reference point by 6 meters

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Laws of motion and physical activities Laws of motion and physical activities

• - change in location of a rotating body • Newton's laws of motion have many • Linear displacement - distance that a applications to physical education system moves in a straight line activities and sports • Speed - how fast an object is moving or distance that an object moves in a specific amount of time • Velocity - includes the direction & describes the of displacement

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10 Law of Law of Inertia

• A body in motion tends to remain in • Inertia - resistance to action or change motion at the same speed in a – In human movement, inertia refers to straight line unless acted on by a resistance to acceleration or deceleration force; a body at rest tends to remain – tendency for the current state of motion to at rest unless acted on by a force be maintained, regardless of whether the • Muscles produce force to start, stop, body segment is moving at a particular velocity or is motionless accelerate, decelerate & change the – the reluctance to change status; only force direction of motion can change status

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Law of Inertia Law of Inertia

• The greater an object’s , the greater its • Force is required to change inertia inertia – Any activity carried out at a steady – the greater the mass, the more force needed to pace in a consistent direction will significantly change an object’s inertia conserve • Examples – Any irregularly paced or directed – Sprinter in starting blocks must apply considerable activity will be very costly to energy force to overcome his resting inertia reserves – Runner on an indoor track must apply considerable force to overcome moving inertia & stop before – Ex. handball & basketball are so hitting the wall much more fatiguing than jogging or – Thrown or struck balls require force to stop them dancing

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Law of Acceleration Law of Acceleration

• A change in the acceleration of a • Acceleration - the rate of change in body occurs in the same direction as velocity the force that caused it. The change – To attain speed in moving the body, a in acceleration is directly strong muscular force is generally proportional to the force causing it necessary and inversely proportional to the • Mass - the amount of in the body mass of the body. – affects the speed & acceleration in physical movements

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11 Law of Acceleration Law of

• A much greater force is required from the • For every action there is an opposite and muscles to accelerate a 230-pound man than equal reaction. than to accelerate a 130-pound man to the – As we place force on a surface by walking same speed over it, the surface provides an equal • A baseball maybe accelerated faster than a resistance back in the opposite direction to shot because of the difference in weight the soles of our feet • The force required to run at half speed is less – Our feet push down & back, while the than the force required to run at top speed surface pushes up & forward • To impart speed to a ball or an object, the • Force of the surface reacting to the force body part holding the object must be rapidly we place on it is ground reaction force accelerated Manual of Manual of Structural Kinesiology Basic Biomechanical Factors & Concepts 3-67 Structural Kinesiology Basic Biomechanical Factors & Concepts 3-68

Law of Reaction Law of Reaction

• We provide the action force – sand dissipates the runner's force reducing while the surface provides the the reaction force with the apparent loss in reaction force forward force & speed – easier to run on a hard track than – sprinter applies a force in excess of 300 on a sandy beach due to the pounds on his starting blocks, which resist difference in the ground reaction with an equal force forces of the two surfaces – in , movement of one part of the – track resists the runner's body produces a reaction in another force, and the reaction part because there is no resistive drives the runner ahead surface to supply a reaction force

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Friction

• Friction - force that results from the – With slick ground or shoe surface resistance between surfaces of two friction is reduced & we are more objects from moving upon one another likely to slip – Depending increased or decreased friction – In skating, we desire decreased may be desired friction so that we may slide across – To run, we depend upon friction forces the ice with less resistance between our feet & the ground so that we may exert force against the ground & propel ourselves forward

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12 Friction Friction

• Static friction or kinetic friction • Static friction is always greater than – Static friction - the amount of kinetic friction friction between two objects that – It is always more difficult to initiate dragging have not yet begun to move an object across a surface than to continue dragging – Kinetic friction - friction occurring – Static friction may be increased by between two objects that are increasing the normal or perpendicular upon one another forces pressing the two objects together such as in adding more weight to one object sitting on the other object

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Friction Friction

• To determine the amount of friction • Rolling friction - resistance to an object forces consider both forces pressing the rolling across a surface such as a ball two objects together & the coefficient of rolling across a court or a tire rolling friction across the ground – depends upon the hardness & roughness of the surface textures – Rolling friction is always much less than static or kinetic friction • Coefficient of friction - ratio between force needed to overcome the friction over the force holding the surfaces together Manual of Manual of Structural Kinesiology Basic Biomechanical Factors & Concepts 3-75 Structural Kinesiology Basic Biomechanical Factors & Concepts 3-76

Balance, equilibrium, & stability Balance, equilibrium, & stability

• Balance - ability to control equilibrium, • Dynamic equilibrium - all applied & either static or dynamic inertial forces acting on the moving body are in balance, resulting in movement • Equilibrium - state of zero acceleration with unchanging speed or direction where there is no change in the speed • To control equilibrium & achieve or direction of the body balance, stability needs to be maximized – static or dynamic • Stability is the resistance to a • Static equilibrium - body is at rest or – change in the body's acceleration completely motionless – disturbance of the body's equilibrium

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13 Balance, equilibrium, & stability Balance, equilibrium, & stability

• Stability is enhanced by determining • Generally, balance is desired body's center of gravity & appropriately • Some circumstances exist where changing it movement is improved when the body • Center of gravity - point at which all of tends to be unbalance body's mass & weight are equally balanced or equally distributed in all directions • Balance - important in resting & moving bodies

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Balance, equilibrium, & stability Balance, equilibrium, & stability

• General factors 2. A person has balance in the direct applicable to enhancing proportion to the size of the base equilibrium, maximizing • The larger the base of support, the more balance stability, & ultimately 3. A person has balance depending on the achieving balance: weight (mass) • The greater the weight, the more balance 1. A person has balance 4. A person has balance, depending on the when the center of gravity height of the center of gravity falls within the base of support • The lower the center of gravity, the more balance

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Balance, equilibrium, & stability Balance, equilibrium, & stability

5. A person has balance, depending on where 6. In anticipation of an oncoming force, the center of gravity is in relation to the base stability may be increased by enlarging the of support size of the base of support in the direction of the anticipated force • Balance is less if the center of gravity is near the edge of the base 7. Equilibrium may be enhanced by increasing • When anticipating an oncoming force, stability the friction between the body & the surfaces may be improved by placing the center of gravity it contacts nearer the side of the base of support expected 8. Rotation about an axis aids balance to receive the force A moving bike is easier to balance than a stationary bike

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14 Balance, equilibrium, & stability Balance, equilibrium, & stability

9. Kinesthetic physiological functions • In walking a person throws the body in contribute to balance and out of balance with each step • The semicircular canals of the inner ear, vision, • In rapid running movements where touch (pressure) & kinesthetic sense all provide moving inertia is high, the center of balance information to the performer gravity has to be lowered to maintain • Balance and its components of equilibrium and stability are essential in all movements and are balance when stopping or changing all affected by the constant force of gravity as direction well as by inertia • In activities the center of gravity needs to be raised as high as possible

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Force Force

• Muscles are the main source of force that • Forces either push or pull on an object in produces or changes movement of a an attempt to affect motion or shape body segment, the entire body, or some • Without forces acting on an object there object thrown, struck, or stopped would be no motion • Strong muscles are able to produce more • Force - product of mass times force than weak muscles acceleration – both maximum and sustained over • Mass - amount of matter in a body a period of time

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Force Force

• The weight of a body segment or the Force = mass x acceleration entire body X the speed of acceleration F = M x A determines the force • ( quantity of motion) - equal to mass – Important in football times velocity – Also important in activities using only a part of the body • The greater the momentum, the greater the – In throwing a ball, the force applied to the resistance to change in the inertia or state of ball is equal to the weight of the arm times motion the speed of acceleration of the arm • Momentum may be altered by , which – Leverage factors are also important is the product of force and time

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15 Force Mechanical loading basics

• Many activities, particularly upper • Significant mechanical loads are extremity, require a summation of forces generated & absorbed by the tissues of from the beginning of movement in the the body lower segment of the body to the twisting • Internal or external forces may cause of the trunk and movement at the these loads shoulder, elbow, and wrist joints • Only muscles can actively generate internal force, but tension in , • Ex. golf drive, shot-putting, discus and connective tissues, ligaments and joints javelin throwing capsules may generate passive internal forces Manual of Manual of Structural Kinesiology Basic Biomechanical Factors & Concepts 3-91 Structural Kinesiology Basic Biomechanical Factors & Concepts 3-92

Mechanical loading basics Mechanical loading basics

• External forces are produced from • Internal forces can outside the body & originate from gravity, – fracture bones inertia or direct contact – dislocate joints • All tissues, in varying degrees, resist – disrupt muscles & connective tissues changes in their shape • To prevent injury or damage from • Tissue deformation may result from deformation the body must be used to external forces, but can result from absorb energy from both internal & internally generated forces external forces

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Mechanical loading basics Mechanical loading basics

• It is advantageous to absorb force over • Excessive tissue deformation due to larger aspects of our body rather than mechanical loading may result from smaller and to spread the absorption rate – Tension (stretching or strain) over a greater period of time – Compression • Stronger & healthier tissues are more – Shear likely to withstand excessive mechanical – Bending loading & the resultant excessive tissue – Torsion (twisting) deformation

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16 Functional application Functional application

• In the performance of various sport skills • In throwing, the individual's inertia & the such as throwing, many applications of ball's inertia must be overcome by the the laws of leverage, motion and balance application of force (Law of inertia) may be found • Muscles of the body provide the force to • In throwing, the angular motion of the move the body parts & the ball levers (bones) of the body (trunk, shoulder, elbow and wrist) is used to give • Law of acceleration is in effect with the linear motion to the ball when it is muscular force necessary to accelerate released the arm, wrist, & hand

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Functional application Functional application

• The greater the force (mass X • The longer the lever, the greater the acceleration) that a person can produce, speed that can be imparted to the ball the faster the arm will move, and thus the – The body from the feet to the fingers can be greater the speed that will be imparted to considered as one long lever – The longer the lever, from natural body the ball length or the body movements to the • The reaction of the feet against the extended backward position, the greater will surface on which the subject stands be the arc through which it accelerates and thus the greater the speed imparted to the applies the law of reaction thrown object

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Functional application Web Sites

Biomechanics: The Magazine of Body Movement and • Short levers are advantageous in taking less www.biomech.com/ Biomechanics World Wide total time to release the ball www.uni-essen.de/~qpd800/WSITECOPY.html – This site enables the reader to search the biomechanics • Balance or equilibrium is a factor in throwing journals for recent information regarding of injury. when the body is rotated posteriorly in the Kinesiology Biomechanics Classes www.uoregon.edu/~karduna/biomechanics/kinesiology.htm beginning of the throw – A listing of numerous biomechanics and kinesiology class site – the body is moved nearly out of balance to the rear, on the web with many downloadable presentations and notes Orthopaedic Biomechanics – balance changes again with the forward movement www.orthobiomech.info/index.htm – balance is reestablished with the follow-through – Numerous text and graphics on biomechanics in orthopaedics when the feet are spread and the knees & trunk are flexed to lower the center of gravity

Manual of Manual of Structural Kinesiology Basic Biomechanical Factors & Concepts 3-101 Structural Kinesiology Basic Biomechanical Factors & Concepts 3-102

17 Web Sites Web Sites

The Physics Classroom Physics Homework Help Http://www.glenbrook.k12.il.us/gbssci/phys/Class/BBoard.html http://tutor4physics.com/index.htm – Numerous topics including the laws of motion and other – Physics formulas, principles, tutorials physics principles GRD Training Corporation Edquest www.physchem.co.za/Motion www.edquest.ca/pdf/sia84notes.pdf – Explanations of physics principles for in motion with quizzes – Text, pictures, and illustrations on simple and complex International Society of Biomechanics machines www.isbweb.org/ COSI Hands-on science centers – Software, data, information, resources, yellow pages, www.cosi.org/files/Flash/simpMach/sm1.swf conferences. A Flash site demonstrating explanations James Madison Memorial High School EuclideanSpace - building a 3D world www.madison.k12.wi.us/jmm/isp/U7PDF08.pdf www.euclideanspace.com – A pdf file explaining the six types of simple machines – Information on how to simulate physical objects with computer Optusnet.com programs www.members.optusnet.com.au/ncrick/converters/moment.html – Conversion formulas for physics variables Manual of Manual of Structural Kinesiology Basic Biomechanical Factors & Concepts 3-103 Structural Kinesiology Basic Biomechanical Factors & Concepts 3-104

Web Sites

Sports Coach—Levers www.brianmac.demon.co.uk/levers.htm – A basic review of levers with excellent links to the study of muscle training & function. Integrated Publishing www.tpub.com/content/engine/14037/index.htm – mechanics

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