#### Transcript 2565 Bio 1

OCR A2 Level Physical Education A 7875 OCR Examinations A Level Physical Education A 7875 Module 2565 : Option B1 part 1 Biomechanical Analysis of Human Movement Previous Next Module 2565 B1.1.1 INDEX Index OCR A2 Level Physical Education A 7875 3 4 5 6 - MECHANICS OF MOTION - LINEAR / ANGULAR MOTION - FORCE - FORCE - DEFINITION OF THE NEWTON - PIN MEN - FREE BODY DIAGRAMS SHAPE OF BODY / FORCES ACTING 7 - PIN MEN - FREE BODY DIAGRAMS 9 - NEWTON’S LAWS OF MOTION 10 - NEWTON’s FIRST LAW 11 - NEWTON’s FIRST LAW - EXAMPLES / THE EFFECT OF FORCES 12 - NEWTON’S SECOND LAW OF MOTION - FORMULA 13 - NEWTON’S SECOND LAW OF MOTION - THE SPRINTER 14 - NEWTON’s THIRD LAW OF MOTION 15 - NEWTON’s THIRD LAW OF MOTION - APPLICATIONS 16 - DISTANCE - DISPLACEMENT 17 - POSITION 18 - SPEED - VELOCITY - DISTANCE-TIME graph 19 - ACCELERATION - DECELERATION / VELOCITY-TIME GRAPH 20 - VECTORS - A VECTOR / SCALAR 21 - VECTORS - ADDING VECTORS 22 - MASS - INERTIA - WEIGHT and MASS are DIFFERENT 23 - The 100m SPRINT - VELOCITY - TIME GRAPH / THE START 24 - The 100m SPRINT - MIDDLE OF RUN / END OF RUN 25 - MOMENTUM 26 - FORCE 27 - FORCE - PROPERTIES OF FORCE / NET FORCE 28 - FORCE - EXAMPLES - NET FORCES 29 - FORCE EXAMPLE - NET FORCES - THE HIGH JUMPER AT TAKE OFF 30 - TYPES OF FORCE ACTING ON A SPORT PERFORMER 31 - WEIGHT 32 - WEIGHT AND MASS Previous Next 33 - REACTION - REACTION FORCES 34 - REACTION - REACTION FORCES EXAMPLES 35 - REACTION - REACTION FORCES EXAMPLES 36 - REACTION - INTERNAL FORCES 37 - FRICTION 38 - FRICTION - PROPERTIES OF FRICTION 39 - FRICTION 40 - FRICTION - FOOTWEAR AND SURFACE 41 - AIR RESISTANCE / FLUID FRICTION (or DRAG) / FACTORS AFFECTING 42 - FLUID FRICTION LOW VALUES OF FLUID FRICTION 43 - FLUID FRICTION HIGH VALUES OF FLUID FRICTION 44 - FLUID FRICTION HIGH VALUES OF FLUID FRICTION 45 - FLUID FRICTION - LAMINAR FLOW 46 - UPTHRUST - A FLOTATION FLUID FORCE Module 2565 B1.1.2 Mechanics of Motion OCR A2 Level Physical Education A 7875 MECHANICS OF MOTION linear MECHANICS of MOTION LINEAR MOTION • motion in a straight line • examples : the movement of the body as a whole in : – sprinting – cycling – swimming – sports vehicles • any motion in which there is no bulk rotation of the object or body in motion – projectiles in flight Previous angular ANGULAR MOTION • motion in which there is a rotation of the body : – tumbling – diving – spinning skater – turning during skiing – spins and turns in dancing • or part of the body : – forearm rotating about the elbow – lower leg rotating about the knee • any twisting or turning motion – wheels on a bike or vehicle Next Module 2565 B1.1.3 OCR A2 Level Physical Education A 7875 Newton’s Laws of Motion FORCE FORCE • FORCE is push or pull • the unit is the NEWTON (10 N is approx the weight of 1 kg) • force changes the state of motion of an object force causes acceleration or deceleration or change of direction the more force the bigger the acceleration • • • Previous force changes the shape of an object Next Module 2565 B1.1.4 OCR A2 Level Physical Education A 7875 Newton’s Laws of Motion FORCE PROPERTIES OF FORCE • force has direction and size (value) • and is therefore a vector • • DEFINITION OF THE NEWTON • one newton of force is the force required : – to produce an acceleration of 1 ms-2 – in a mass of 1 kg when describing a force it is important to explain where the force acts (the point of action) as well as the direction • • • Previous Next this is related to the inertial property of mass the more force applied, the more acceleration produced see Newton’s second law Module 2565 B1.1.5 OCR A2 Level Physical Education A 7875 Newton’s Laws of Motion PIN MEN - FREE BODY DIAGRAMS SHAPE OF BODY • should be represented approximately DIAGRAM • shows force in black acting downwards on the ground • force in red acting upwards on the jumper’s foot FORCES ACTING • forces are represented by arrows • in the direction of the force • the point of action of the force should be shown where the force acts – at the foot – on the body – on the hand • the length of the arrow represents the size of the force Previous Next Module 2565 B1.1.6 OCR A2 Level Physical Education A 7875 Newton’s Laws of Motion PIN MEN - FREE BODY DIAGRAMS FORCES ACTING • forces are represented by arrows • in the direction of the force • the point of action of the force should be shown where the force acts – at the foot – on the body – on the hand • the length of the arrow represents the size of the force Previous DIAGRAM • shows four forces acting • 2 forces acting up on the foot and down on the body • • Next 2 forces acting backwards on the body and forwards on the foot longer arrows mean greater force Module 2565 B1.1.7 OCR A2 Level Physical Education A 7875 Newton’s Laws of Motion PIN MEN - FREE BODY DIAGRAMS FORCES ACTING • forces are represented by arrows • in the direction of the force • the point of action of the force should be shown where the force acts – at the foot – on the body – on the hand • the length of the arrow represents the size of the force Previous DIAGRAM • shows four forces acting • 2 forces acting horizontally • 2 forces acting vertically • longer arrows mean greater force Next Module 2565 B1.1.8 OCR A2 Level Physical Education A 7875 Newton’s Laws of Motion NEWTON’S LAWS OF MOTION 1st LAW zero net force acts - constant velocity 2nd LAW a net force acts F=ma - produces acceleration NEWTON'S LAWS 3rd LAW one body exerts force on another - reaction Previous Next Module 2565 B1.1.9 Newton’s Laws of motion OCR A2 Level Physical Education A 7875 NEWTON’s FIRST LAW NEWTON’S FIRST LAW • this law is used when zero net force is applied to an object • this doesn’t mean that zero force acts, but that all forces must cancel out • with zero net force an object – is stationary or – moves at constant speed in the same direction • for the sprinter, horizontal forces cancel out • and vertical forces cancel out • hence he / she travels at constant speed Previous Next Module 2565 B1.1.10 Newton’s Laws of motion OCR A2 Level Physical Education A 7875 NEWTON’s FIRST LAW NEWTON’S FIRST LAW • examples : – a sprinter running at constant speed – a cyclist going at constant speed – a swimmer swimming at constant speed – any vehicle going at constant speed – any sportsperson standing still THE EFFECT OF FORCES • this law does not mean that there are no forces • very large forces can act • but if the object is going at constant speed • these forces MUST cancel out Previous Next Module 2565 B1.1.11 Newton’s Laws of Motion OCR A2 Level Physical Education A 7875 NEWTON’S SECOND LAW OF MOTION NEWTON’S SECOND LAW • this law is used when a NET FORCE acts on an object • net force forwards produces acceleration - positive • net force backwards produces deceleration - negative • net force sideways produces change of direction FORMULA • force = mass x acceleration • F = m x a • • Previous hence the bigger the force the bigger the acceleration the bigger the mass, the smaller the acceleration Next Module 2565 B1.1.12 Newton’s Laws of Motion OCR A2 Level Physical Education A 7875 NEWTON’S SECOND LAW OF MOTION THE SPRINTER • four forces are acting • upwards force = downwards force • • • backwards force is bigger than forwards force • therefore there is a net backwards force producing a negative acceleration or deceleration • • Previous Next therefore there is no upward acceleration the sprinter runs horizontally Module 2565 B1.1.13 Newton’s Laws of motion OCR A2 Level Physical Education A 7875 NEWTON’s THIRD LAW OF MOTION NEWTON’S THIRD LAW • this law is used when two bodies exert forces on one another • action and reaction are equal and opposite in direction • action of jumper down on ground (force in black) • = reaction of ground up on jumper (force in red) • the harder you push down on the ground, the more the ground pushes up on you Previous Next Module 2565 B1.1.14 Newton’s Laws of motion OCR A2 Level Physical Education A 7875 NEWTON’s THIRD LAW OF MOTION APPLICATIONS • at the sprint start - the athlete pushes back on the blocks as hard as possible • the blocks push forward - and provides forward acceleration - on the athlete • a swimmer drives backwards on water with hands and feet (force in black) • the water pushes the swimmer forward (force in red) Previous Next Module 2565 B1.1.15 Linear Motion - Measurements OCR A2 Level Physical Education A 7875 DISTANCE - DISPLACEMENT DISTANCE • means the total path length moved by a body • example : – a 10,000 m race is run round and round the track – 25 times 400 m, starting and finishing POSITION are the same – distance travelled is 10,000 m • unit the metre m Previous Next DISPLACEMENT • this means the vector distance from a fixed point (starting point or origin) • the actual ‘as the crow flies’ distance between start and finish (with direction included) • example : – the start and finish of a long distance race (Stage 5 of the Tours de France) – may be 190 km apart due West, but the distance travelled may be 250 km! • unit the metre m Module 2565 B1.1.16 Linear Motion - Measurements OCR A2 Level Physical Education A 7875 POSITION POSITION • a way of explaining where a point is relative to some fixed point • position is usually expressed in terms of coordinates (x and y) like a graph in maths • example : – the centre forward takes a shot from a position 20 m out from the goal line, and 10m to the left of the left hand post – the left hand post is the fixed point or origin of measurement – 20 m and 10 m are the coordinates of the position of the centre forward relative to that point. Previous Next Module 2565 B1.1.17 Linear Motion - Measurements OCR A2 Level Physical Education A 7875 SPEED - VELOCITY SPEED • = distance moved v = s time taken t • = scalar (no direction) unit ms-1 VELOCITY • = speed in a given direction • = vector DISTANCE / TIME graph • gradient of graph is velocity Previous Next Module 2565 B1.1.18 Linear Motion - Measurements OCR A2 Level Physical Education A 7875 ACCELERATION ACCELERATION • = change of velocity time taken to change a=v-u t unit ms-2 • • • acceleration is in the same direction as net force acceleration is a vector (has direction) an object changing direction is accelerating, since the velocity changes • example : – swerving rugby player – direction of acceleration is along the radius of the curve (path of player) – this is a radial acceleration DECELERATION • is negative acceleration (slowing down) VELOCITY / TIME graph • gradient of graph is acceleration • area under graph is distance travelled Previous Next Module 2565 B1.1.19 Linear Motion - Measurements OCR A2 Level Physical Education A 7875 VECTORS A VECTOR • has direction as well as size (magnitude or value) • • • • a vector can be represented by a line on a piece of paper (graph paper) the length of the line represents the size (say the value of a force in newtons) the angle of the line to the horizontal represents the direction examples of vectors are : – force, acceleration, velocity, weight, momentum A SCALAR • has size (value) only • examples of scalars are : – mass, temperature, energy, speed, distance, volume, pressure, power. Previous Next Module 2565 B1.1.20 Linear Motion - Measurements VECTORS OCR A2 Level Physical Education A 7875 ADDING VECTORS • is a process which involves finding the size and direction of a resultant of 2 or more vectors • complete the parallelogram as shown in the example • the resultant is the diagonal of the parallelogram • the resultant of two vectors at right angles is found by completing the rectangle • • F2 = F12 + F22 q = tan-1(F2/F1) Previous Next Module 2565 B1.1.21 Linear Motion - Measurements OCR A2 Level Physical Education A 7875 MASS - INERTIA MASS • the mass of a body or object is the same everywhere and is related to amount of matter and inertia WEIGHT and MASS are DIFFERENT INERTIA • is the property of mass which means that it is hard to get a massive body moving, and also hard to stop it once it is moving • • • weight is produced by the gravitational force field acting on objects / bodies it is a force which acts downwards towards the centre of the Earth measured in kilogrammes kg Previous Next Module 2565 B1.1.22 Linear Motion - Measurements The 100m SPRINT OCR A2 Level Physical Education A 7875 VELOCITY - TIME GRAPH • steep slope for first part = large acceleration • this corresponds with a large forward net force applied at the start THE START Previous Next • • friction is large provides forward acceleration • net force forwards (resultant) shown in black Module 2565 B1.1.23 Linear Motion - Measurements The 100m SPRINT OCR A2 Level Physical Education A 7875 MIDDLE OF RUN • the velocity time graph is almost level • which means that acceleration is almost zero • therefore forces cancel out END OF RUN • the velocity time graph has a small negative slope • which means that the sprinter decelerates • therefore there is a net force backwards shown in black Previous Next Module 2565 B1.1.24 Linear Motion - Momentum OCR A2 Level Physical Education A 7875 MOMENTUM MOMENTUM • a concept derived from Newton's second law which says : • force = rate of change of momentum • • • (Linear) momentum = mass x velocity linear means in a straight line momentum includes both mass and velocity • so an object which has a lot of momentum requires a lot of force to stop it which is a good argument for fast heavy rugby players or American footballers • • momentum is a vector (and therefore has direction) Previous Next Module 2565 B1.1.25 Force FORCE OCR A2 Level Physical Education A 7875 FORCE • FORCE is push or pull • the unit is the NEWTON (10 N is approx the weight of 1 kg) • • • force changes the state of motion of an object force causes acceleration or deceleration or change of direction the more force the bigger the acceleration • force changes the shape of an object DEFINITION OF THE NEWTON • one newton of force is the force required : – to produce an acceleration of 1 ms-2 – in a mass of 1 kg • • • this is related to the inertial property of mass the more force applied, the more acceleration produced see Newton’s second law, F = m x a Previous Next Module 2565 B1.1.26 OCR A2 Level Physical Education A 7875 Force FORCE PROPERTIES OF FORCE • force has direction and size (value) • and is therefore a VECTOR • • when describing a force it is important to explain where the force acts (the point of action) as well as the direction NET FORCE • net force is the result of all forces added together taking the direction into account (see VECTORS) • • • net force forwards produces acceleration - positive net force backwards produces deceleration - negative net force sideways produces change of direction Previous Next Module 2565 B1.1.27 Force FORCE OCR A2 Level Physical Education A 7875 EXAMPLES - NET FORCES • sprinter accelerating • jumper taking off • projectile in flight • jumper landing – as feet make contact with ground – net force backwards causes deceleration EXAMPLES - ZERO NET FORCE • sprinter at full speed • swimmer at full speed Previous Next Module 2565 B1.1.28 Force FORCE OCR A2 Level Physical Education A 7875 EXAMPLE - NET FORCES - THE HIGH JUMPER AT TAKE OFF • the net force is made up from a number of forces which add together • in the case of the high jumper taking off the following forces act : • his weight (acting downwards) • the reaction force acting upwards • and a friction force acting backwards • these forces add up to a net force as shown • • which will cause upward acceleration - for take-off and forward rotation (over the bar) Previous Next Module 2565 B1.1.29 Types of Force OCR A2 Level Physical Education A 7875 TYPES OF FORCE ACTING ON A SPORT PERFORMER WEIGHT MAGNUS EFFECT REACTION TYPE OF FORCE AIR RESISTANCE FLUID FRICTION FRICTION UPTHRUST Previous Next Module 2565 B1.1.30 Types of Force - Weight WEIGHT OCR A2 Level Physical Education A 7875 WEIGHT • is produced by the gravitational force field acting on objects / bodies • it is a force which acts downwards towards the centre of the Earth • • • • • weight is the predominant force experienced by objects moving freely through air flight of thrown object is a parabola if no air resistance your weight would be approximately the same everywhere on the Earth’s surface value g = the gravitational field strength = 10 Newtons per kilogramme variations occur between poles and equator, and at altitude – less weight at altitude means slightly further jumps and throws Previous Next Module 2565 B1.1.31 Types of Force - Weight OCR A2 Level Physical Education A 7875 WEIGHT AND MASS WEIGHT and MASS are DIFFERENT WEIGHT • is a force • depends on gravity – therefore zero in outer space – one sixth of Earth value on the moon • measured in newtons N • calculated using W = m x g • g = 10 newtons per kg mass MASS • mass is the same everywhere in the universe regardless of gravity • and is related to amount of matter • and inertia • inertia is the property of mass which means that it is – hard to get a massive body moving – also hard to stop it once it is moving • Previous Next measured in kilogrammes kg Module 2565 B1.1.32 Types of Force - Reaction OCR A2 Level Physical Education A 7875 REACTION REACTION FORCES • are forces acting via Newton’s Third Law • when one object pushes on another, the first object experiences a force equal but opposite in direction to the second • jumper pushes down on the ground, ground pushes up on the jumper Previous Next • weight lifter pulls up on weight, weight pulls down on lifter Module 2565 B1.1.33 Types of Force - Reaction OCR A2 Level Physical Education A 7875 REACTION REACTION FORCES • swimmer pushes backwards on the water • reaction force thrusts the swimmer forward • canoeist pushes backwards on the water • reaction force thrusts the canoe forward Previous Next Module 2565 B1.1.34 Types of Force - Reaction OCR A2 Level Physical Education A 7875 REACTION REACTION FORCES • sprinter pushes back and down on the ground • the ground pushes upwards and forwards on the sprinter REACTION FORCES • in cycling, the tyre on the rear wheel pushes backward on the ground • Previous Next the ground pushes forward on the rear wheel Module 2565 B1.1.35 Types of Force - Reaction OCR A2 Level Physical Education A 7875 REACTION INTERNAL FORCES • are exerted on both origin and insertion of a muscle. • the force on the insertion is a reaction to the force on the origin • • • Previous force on origin pulls bone H to the right force on insertion pulls bone U to the left the two forces are equal in size but opposite in direction Next Module 2565 B1.1.36 Types of Force - Friction OCR A2 Level Physical Education A 7875 FRICTION FRICTION • is a force which acts sideways between two surfaces which tend to slide past one another • • • this force enables sportspeople to accelerate, slow down, swerve, walk, run grip of footwear on floor surface friction acts forwards on the feet of an accelerating runner Previous Next Module 2565 B1.1.37 Types of Force - Friction OCR A2 Level Physical Education A 7875 FRICTION PROPERTIES OF FRICTION • friction depends on the force pressing the surfaces together • but not on the area of contact • example : – inverted wings on racing cars to increase down force on wheels – this increases cornering friction • example : – when riding a mountain bike up a steep hill – you should sit back over the rear wheel – to increase downward force on rear wheel Previous Next Module 2565 B1.1.38 Types of Force - Friction OCR A2 Level Physical Education A 7875 FRICTION FRICTION • enables swerving by games players – rugby – soccer – hockey – tennis • • the friction force then acts sideways to the direction of motion and changes the direction of motion Previous Next Module 2565 B1.1.39 Types of Force - Friction OCR A2 Level Physical Education A 7875 FRICTION FOOTWEAR AND SURFACE • studs, spikes increase friction to enable better swerving and accelerating and decelerating in games or track situations • this applies to soft or wet surfaces • • for dry hard surfaces solid smooth rubber soles can give better friction – discus / hammer shoes – rock climbing shoes – tennis shoes for concrete surfaces • in snow and ice, long slender footwear (skates / skis) – forward friction is low – sideways friction is high Previous Next Module 2565 B1.1.40 OCR A2 Level Physical Education A 7875 Types of Force - Air-resistance / Fluid Friction AIR RESISTANCE / FLUID FRICTION FLUID FRICTION (or DRAG) • this is a term applying to objects moving through fluids (gases or liquids) • The force acts in the opposite direction to the direction of motion FLUID FRICTION FORCE DEPENDS ON • the shape and size of the moving object • the speed of the moving object • the streamlining effect, hence : – body position and shape for swimmer – shape of helmets for cyclists – use of lycra clothing – shape of sports vehicles (cars / bikes) Previous Next shape size FLUID FRICTION speed streamlining Module 2565 B1.1.41 OCR A2 Level Physical Education A 7875 Types of Force - Air-resistance / Fluid Friction FLUID FRICTION LOW VALUES OF FLUID FRICTION • low values compared with other forces • • • • • • any sprinter or game player air resistance is usually much less than friction effects and weight therefore streamlining is seen as less important shot / hammer in flight air resistance much less than weight therefore angle of release should be around 45o Previous Next Module 2565 B1.1.42 OCR A2 Level Physical Education A 7875 Types of Force - Air-resistance / Fluid Friction FLUID FRICTION HIGH VALUES OF FLUID FRICTION • any sportsperson or vehicle moving through water will have high values of fluid friction • therefore fluid friction is the critical factor governing swimming speed • • Previous body shape / cross section and clothing (surface material to assist laminar flow) are adjusted to minimise fluid friction Next Module 2565 B1.1.43 OCR A2 Level Physical Education A 7875 Types of Force - Air-resistance / Fluid Friction FLUID FRICTION HIGH VALUES OF FLUID FRICTION • a cyclist travels much faster than a runner therefore has high fluid friction • he / she crouches low to reduce forward cross section • the helmet is designed to minimise turbulent flow • clothing / wheel profile are designed to assist streamlining Previous Next Module 2565 B1.1.44 OCR A2 Level Physical Education A 7875 Types of Force - Air-resistance / Fluid Friction FLUID FRICTION FLUID FRICTION (or DRAG) • this depends on laminar flow, the smooth flowing of air or water past an object • laminar means flowing in layers • streamlining assists laminar flow • when vortices are formed the fluid doesn’t flow smoothly – bits of fluid are flung randomly sideways – which causes drag – because bits of fluid are dragged along with the moving object (cycle helmet) Previous Next Module 2565 B1.1.45 OCR A2 Level Physical Education A 7875 Types of Force UPTHRUST - A FLOTATION FLUID FORCE UPTHRUST • is a force acting upwards on any object immersed or partially immersed in water (or any fluid) • this is the force which enables objects to float • • • it is caused by displacement of fluid the fluid is pushed aside by the floating object the fluid (as a reaction force) pushes upwards on the floating object • all swimmers and sports boats experience this force Previous Next Module 2565 B1.1.46