1 / 46

OCR Examinations A Level Physical Education A 7875 Module 2565 : Option B1 part 1

OCR Examinations A Level Physical Education A 7875 Module 2565 : Option B1 part 1 Biomechanical Analysis of Human Movement. 33 - REACTION - REACTION FORCES 34 - REACTION - REACTION FORCES EXAMPLES 35 - REACTION - REACTION FORCES EXAMPLES 36 - REACTION - INTERNAL FORCES

colette-garner
Télécharger la présentation

OCR Examinations A Level Physical Education A 7875 Module 2565 : Option B1 part 1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. OCR Examinations A Level Physical Education A 7875 Module 2565 : Option B1 part 1 Biomechanical Analysis of Human Movement

  2. 33 - REACTION - REACTION FORCES 34 - REACTION - REACTION FORCESEXAMPLES 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 Index 3 - MECHANICS OF MOTION - LINEAR / ANGULAR MOTION 4 - FORCE 5 - FORCE - DEFINITION OF THE NEWTON 6 - 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 INDEX

  3. 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 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 Mechanics of Motion MECHANICS OF MOTION

  4. 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 decelerationor change of direction the more force the bigger the acceleration force changes the shape of an object Newton’s Laws of Motion FORCE

  5. Newton’s Laws of Motion 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 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

  6. SHAPE OF BODY should be represented approximately 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 DIAGRAM shows force in black acting downwards on the ground Newton’s Laws of Motion PIN MEN - FREE BODY DIAGRAMS • force in red acting upwards on the jumper’s foot

  7. 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 Newton’s Laws of Motion PIN MEN - FREE BODY DIAGRAMS DIAGRAM • shows four forces acting • 2 forces acting up on the foot and down onthe body • 2 forces acting backwards on the body and forwards on the foot • longer arrows mean greater force

  8. 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 Newton’s Laws of Motion PIN MEN - FREE BODY DIAGRAMS DIAGRAM • shows four forces acting • 2 forces acting horizontally • 2 forces acting vertically • longer arrows mean greater force

  9. Newton’s Laws of Motion NEWTON’S LAWS OF MOTION

  10. Newton’s Laws of motion NEWTON’S FIRST LAW this law is used when zero net forceis 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 stationaryor moves at constant speed in the same direction NEWTON’s FIRST LAW • for the sprinter, horizontal forces cancel out • and vertical forces cancel out • hence he / she travels at constant speed

  11. 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 Newton’s Laws of motion 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 NEWTON’s FIRST LAW

  12. FORMULA force = mass x acceleration F = m x a hence the bigger the force the bigger the acceleration the bigger the mass, the smaller the acceleration Newton’s Laws of Motion NEWTON’S SECOND LAW this law is used when a NET FORCEacts on an object net forceforwards produces acceleration - positive net forcebackwardsproduces deceleration - negative net force sideways produces change of direction NEWTON’S SECOND LAW OF MOTION

  13. Newton’s Laws of Motion NEWTON’S SECOND LAW OF MOTION THE SPRINTER • four forces are acting • upwards force = downwards force • therefore there is no upward acceleration • the sprinter runs horizontally • backwards force is bigger than forwards force • therefore there is a net backwards force • producing a negative acceleration • or deceleration

  14. Newton’s Laws of motion 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 equalandopposite in direction • actionof jumper down on ground (force in black) • = reactionof ground up on jumper (force in red) • the harder you push down on the ground, the more the ground pushes up on you

  15. 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) Newton’s Laws of motion NEWTON’s THIRD LAW OF MOTION • the water pushes the swimmer forward (force in red)

  16. 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 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 Linear Motion - Measurements DISTANCE - DISPLACEMENT

  17. Linear Motion - Measurements 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.

  18. SPEED = distance moved v =s unit ms-1time taken t = scalar (no direction) VELOCITY = speed in a given direction = vector DISTANCE / TIME graph gradient of graph is velocity Linear Motion - Measurements SPEED - VELOCITY

  19. Linear Motion - Measurements ACCELERATION ACCELERATION • = change of velocitya = v - uunit ms-2 time taken to change t • 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

  20. 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 Linear Motion - Measurements VECTORS • 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.

  21. 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 Linear Motion - Measurements VECTORS • 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)

  22. MASS the mass of a body or object is the same everywhere 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, and also hard to stop it once it is moving measured in kilogrammes kg WEIGHT and MASS are DIFFERENT 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 Linear Motion - Measurements MASS - INERTIA

  23. VELOCITY - TIME GRAPH steep slope for first part = large acceleration this corresponds with a large forward net force applied at the start Linear Motion - Measurements The 100m SPRINT THE START • friction is large • provides forward acceleration • net force forwards (resultant) shown in black

  24. MIDDLE OF RUN the velocity time graph is almost level which means that acceleration is almost zero therefore forces cancel out Linear Motion - Measurements The 100m SPRINT 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

  25. 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) Linear Motion - Momentum MOMENTUM

  26. 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 decelerationor change of direction the more force the bigger the acceleration force changes the shape of an object Force FORCE 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

  27. Force NET FORCE net force is the result of all forces added together taking the direction into account (see VECTORS) net forceforwards produces acceleration - positive net forcebackwardsproduces deceleration - negative net force sideways produces change of direction 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

  28. EXAMPLES - NET FORCES sprinter accelerating jumper taking off projectile in flight jumper landing as feet make contact with ground net force backwards causes deceleration Force FORCE EXAMPLES - ZERO NET FORCE • sprinter at full speed • swimmer at full speed

  29. 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 : Force FORCE • 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)

  30. Types of Force TYPES OF FORCE ACTING ON A SPORT PERFORMER

  31. 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 Types of Force - Weight WEIGHT • 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

  32. 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 newtonsN calculated using W = m x g g = 10 newtons per kg mass Types of Force - Weight WEIGHT AND 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 • measured in kilogrammeskg

  33. 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 weight lifter pulls up on weight, weight pulls down on lifter Types of Force - Reaction REACTION • jumperpushes down on the ground, ground pushes up on the jumper

  34. REACTION FORCES swimmer pushes backwards on the water reaction force thrusts the swimmer forward Types of Force - Reaction REACTION • canoeist pushes backwards on the water • reaction force thrusts the canoe forward

  35. REACTION FORCES sprinter pushes back and down on the ground the ground pushes upwards and forwards on the sprinter Types of Force - Reaction REACTION FORCES in cycling, the tyre on the rear wheel pushes backward on the ground the ground pushes forward on the rear wheel REACTION

  36. 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 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 Types of Force - Reaction REACTION

  37. 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 Types of Force - Friction FRICTION

  38. 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 Types of Force - Friction FRICTION

  39. 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 Types of Force - Friction FRICTION

  40. 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 Types of Force - Friction FRICTION

  41. 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 Types of Force - Air-resistance / Fluid Friction AIR RESISTANCE / FLUID FRICTION 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)

  42. 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 Types of Force - Air-resistance / Fluid Friction FLUID FRICTION • shot / hammer in flight • air resistance much less than weight • therefore angle of release should be around 45o

  43. 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 body shape / cross section and clothing (surface material to assist laminar flow) are adjusted to minimise fluid friction Types of Force - Air-resistance / Fluid Friction FLUID FRICTION

  44. HIGH VALUES OF FLUID FRICTION a cyclist travels much faster than a runner therefore has highfluid 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 Types of Force - Air-resistance / Fluid Friction FLUID FRICTION

  45. 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 Types of Force - Air-resistance / Fluid Friction FLUID FRICTION • 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)

  46. 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 upwardson the floating object all swimmers and sports boats experience this force Types of Force UPTHRUST - A FLOTATION FLUID FORCE

More Related