Biomechanics 1

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Biomechanics 1

  1. 1. Test feedback
  2. 2. Synovial joint structure - knee Femur Tibia Patella Tendon Cruciate ligaments Articular cartilage Synovial fluid within synovial cavity Bursa Bursa Meniscus Pad of fat Ligament Joint capsule Quadriceps Synovial membrane
  3. 3. Structure of a synovial joint Ligament Meniscus Joint capsule Articular cartilage Synovial fluid Bursa Features that improve STABILITY Features that improve MOBILITY
  4. 4. Joint Capsule Discs of fibro-cartilage Synovial fluid Synovial membrane Articular cartilage Bursa Ligaments Pads of fat Meniscus Fibrous tissue encasing the joint Forming a capsule around the joint adds stability C-shaped rims of fibrocartilage Acts as shock absorbers A fluid that fills the joint capsule Nourishes and lubricates the articular cartilage Lines the joint capsule Secretes synovial fluid Covers the articulating surfaces of the bones Prevents friction between the ends of bones White fibrous connective tissue which attaches bone to bone By securing the bones of joints together it adds significantly to joint stability A sac filled with synovial fluid located between tendons/ligaments and bones To reduce friction where tendons, ligaments, muscle or bones might rub together Fatty tissue located between fibrous capsule and bone or muscle Provides a cushion between the joint capsule and the bone/muscle Wedges of fibrocartilage found between bones Stabilises joint by improving the fit between bones. Reduces wear & tear STRUCTURE & FUNCTIONAL CHARACTERISTICS OF SYNOVIAL JOINT Joint feature Structure Function
  5. 5. Anatomy and Physiology 5 Motion and movement 1 Biomechanics: Newton’s Laws of Motion
  6. 6. SPORTS BIOMECHANICS Biomechanics is the study of body movements and of the forces acting on the musculoskeletal system
  7. 7. Specification <ul><li>Candidates should be able to: </li></ul><ul><li>Define Newton’s law of motion </li></ul><ul><li>Describe the types of motion produced (linear, angular or general) </li></ul><ul><li>Describe the effect of force, direction of the force and the position of application of force on a body </li></ul><ul><li>Define centre of mass </li></ul><ul><li>Explain the effect of changes on the position of the centre of mass and the area of support when applied to practical techniques </li></ul><ul><li>Carry out practical analysis of typical physical actions </li></ul>
  8. 8. Learning Objectives <ul><li>To know and understand </li></ul><ul><li>Newton’s three laws of motion </li></ul><ul><li>The types of movement that can be produced </li></ul><ul><li>Be able to </li></ul><ul><li>Apply the laws of motion to explain the type of movement produced </li></ul><ul><li>Describe the effect of force in sporting actions </li></ul>
  9. 9. Types of motion
  10. 10. Linear motion <ul><li>When a body moves in a straight or curved line with all it’s parts moving in the same direction and at the same speed . </li></ul>
  11. 11. Angular motion <ul><li>When a body or part of a body moves in a circle or part of a circle about a particular point called the axis of rotation </li></ul><ul><li>Movement occurs around a fixed point or axis (including around the joints of the body) </li></ul>
  12. 12. So what type of motion is this? <ul><li>Consider……. </li></ul><ul><li>Flight of javelin </li></ul><ul><li>Run up </li></ul><ul><li>Javelin </li></ul><ul><li>Torso </li></ul><ul><li>Leg action </li></ul><ul><li>Arm action </li></ul><ul><li>Linear motion </li></ul><ul><li>Linear motion </li></ul><ul><li>Linear motion </li></ul><ul><li>Angular motion </li></ul><ul><li>Upper legs rotate about shoulder joints </li></ul><ul><li>Lower legs around the knee joint </li></ul><ul><li>Feet around the ankle joints </li></ul><ul><li>Angular motion </li></ul><ul><li>Non-throwing arm rotates about shoulder joint </li></ul>GENERAL MOTION
  13. 13. General motion <ul><li>A combination of linear and general motion </li></ul>
  14. 14. Identify the types of motion 5 3 4 2 1
  15. 15. Task <ul><li>Write a definition of </li></ul><ul><ul><li>Linear motion </li></ul></ul><ul><ul><li>Angular motion </li></ul></ul><ul><ul><li>General motion </li></ul></ul><ul><li>Give at least one sporting example for each of these types of motion and explain why it is that type of motion </li></ul>
  16. 16. Force <ul><li>A push or a pull that alters the state of motion of a body </li></ul><ul><li>What can a force do to an object? </li></ul>
  17. 17. Effects of force <ul><li>A force can cause… </li></ul><ul><li>A body at rest to move </li></ul><ul><li>A moving body to change direction </li></ul><ul><li>A moving body to accelerate </li></ul><ul><li>A moving body the decelerate </li></ul><ul><li>A body to change its shape </li></ul><ul><li>Give a relevant sporting example for each of these effects </li></ul>
  18. 18. Effects of force <ul><li>What factors affect the extent of these effects? </li></ul><ul><li>S ize of the force (how many Newtons) </li></ul><ul><li>A pplication of force </li></ul><ul><li>D irection of the force </li></ul>
  19. 19. Motion and movement Sir Isaac Newton
  20. 20. Video – Newton’s 3 laws of motion
  21. 21. Newton’s 1 st law of motion A body will continue in a state of rest or uniform velocity unless acted upon by an external force Inertia = resistance of a body to change its state of motion “ Law of Inertia”
  22. 22. Newton’s 2 nd law of motion “ When a force acts on an object, the rate of change of momentum experienced by the object is proportional to the size of the force and takes place in the direction in which the force acts” Law of Acceleration F = ma F is the applied force m is the mass of the body/object a is the acceleration of the body/object ‘ The acceleration of an object is directly proportional to the force causing it and is inversely proportional to the mass of the objects’
  23. 23. Newton’s 2 nd law of motion <ul><li>How is velocity different to speed? </li></ul><ul><li>Both are the distance covered per second </li></ul><ul><li>But velocity is a vector quantity and hence has direction as well as size </li></ul><ul><li>What is Acceleration? </li></ul><ul><li>The rate of change of velocity </li></ul><ul><li>Acceleration = change in velocity/time </li></ul>
  24. 24. Newton’s 2 nd law <ul><li>What is momentum? </li></ul><ul><li>Momentum = mass x velocity </li></ul><ul><li>= mv </li></ul><ul><li>2 nd law </li></ul><ul><li>F = ma </li></ul><ul><li>F is the force applied, m is the mass of the object and a is the acceleration </li></ul>
  25. 25. Newton’s 2 nd law of motion When a force acts on an object, the rate of change of momentum experienced by the object is proportional to the size of the force and takes place in the direction in which the force acts “ Law of Acceleration” The acceleration of an object is directly proportional to the force causing it and is inversely proportional to the mass of the objects F = ma
  26. 26. Newton’s 3 rd law For every action there is an equal and opposite reaction When a body exerts a force on another body then there is an equal and opposite force exerted back Action Reaction
  27. 27. Law’s of motion
  28. 28. Law’s of motion <ul><li>Ensure that you have a definition of each of the 3 laws of motion </li></ul><ul><li>Ensure that you also know them by their alternative names (e.g. Law of Inertia) </li></ul><ul><li>Apply each of Newton’s 3 laws of motion to </li></ul><ul><ul><li>A penalty kick </li></ul></ul><ul><ul><li>Another sporting action of your choice </li></ul></ul>
  29. 29. Laws of Motion <ul><li>http://www.youtube.com/watch?v=UVdqxYyFRKY </li></ul>
  30. 30. Generating motion <ul><li>How can you produce linear motion? </li></ul><ul><li>A force is applied through the centre of mass of the object. </li></ul><ul><li>How can you produce angular motion? </li></ul><ul><li>A force is applied off centre for angular motion to occur/eccentric force (not through centre of gravity) applied outside centre of mass </li></ul>
  31. 31. Exam questions 2008 <ul><li>Movement can be described as linear, angular or general motion </li></ul><ul><li>Use a practical example to describe how linear motion can be produced </li></ul><ul><li>2 marks </li></ul><ul><li>(May 2008) </li></ul>
  32. 32. Exam answers 2008 <ul><li>Use a practical example to describe how linear motion can be produced </li></ul><ul><li>2 marks </li></ul><ul><li>A force is applied through the centre of mass/gravity of the object. </li></ul><ul><li>2. A golfer/footballer must hit the ball through its centre of mass/gravity to ensure it travels in a straight line. </li></ul>
  33. 33. Exam question 2008 <ul><li>1c Explain, using a practical example, how either size or direction of force an affect performance in PE and sport </li></ul><ul><li>2 marks </li></ul><ul><li>(Jan 2008) </li></ul>
  34. 34. Exam answer 2008 <ul><li>Explanation [1 mark] </li></ul><ul><li>Size of force affects how far/fast an object travels </li></ul><ul><li>Direction of force affects the direction/trajectory of the object/distance a flighted object will travel/if direction of force outside centre of gravity spin will occur/if direction of force is applied through centre of gravity it will cause linear motion </li></ul><ul><li>Larger size of force causes object to accelerate faster/smaller size of force causes object to accelerate slower </li></ul><ul><li>Larger size of force causes object to decelerate faster/smaller size of force causes object to decelerate slower </li></ul><ul><li>Size of force can change an objects shape more/less </li></ul><ul><li>Example [1 mark] </li></ul><ul><li>A snooker player must apply the correct size of force to the cue ball to ensure the colour ball reaches the pocket. </li></ul><ul><li>A golfer must ensure the ball is struck in the correct direction from the tee to hit the green/avoid hazards. </li></ul>
  35. 35. Exam question 2007 <ul><li>1b (iv) Apply Newton’s 3 Laws of Motion to a strength training exercise </li></ul><ul><li>3 marks </li></ul><ul><li>(May 2007) </li></ul>
  36. 36. Exam answer 2007 <ul><li>1b (iv) Apply Newton’s 3 Laws of Motion to a strength training exercise </li></ul><ul><li>3 marks </li></ul><ul><li>3 marks maximum (no application no marks) </li></ul><ul><li>1 (Law of Inertia/Newtons’ 1st Law) </li></ul><ul><li>Weight/performer will not move unless force applied </li></ul><ul><li>2 (Law of Acceleration/ Newtons’ 2nd Law) </li></ul><ul><li>More force applied greater weight lifted/weight lifted more quickly/athlete must apply force at end of lift to control weight/more weight lifted requires more force to be applied </li></ul><ul><li>3 (Law of Reaction/ Newtons’ 3rd Law) </li></ul><ul><li>Performer pushes against resistance/weight and force applied back against performer </li></ul>
  37. 37. Exam question 2005 <ul><li>1b When hitting a ball in tennis an understanding of force is important. </li></ul><ul><li>Explain how force can cause the ball to: </li></ul><ul><li>Move straight </li></ul><ul><li>Spin </li></ul><ul><li>2 marks </li></ul><ul><li>(May 2005) </li></ul>
  38. 38. Exam answer 2005 <ul><li>1b When hitting a ball in tennis an understanding of force is important. </li></ul><ul><li>Explain how force can cause the ball to: </li></ul><ul><li>Move straight </li></ul><ul><li>A force is applied through the centre of gravity/mass / the player must hit the ball through the middle (centre of gravity) of the ball. </li></ul><ul><li>(ii) Spin 2. </li></ul><ul><li>A force is applied off centre/eccentric force/hitting a ball on the side will create spin. </li></ul>
  39. 39. Exam question 2004 <ul><li>1 c During an analysis of practical activities, movement can be described as linear, angular or general motion </li></ul><ul><li>Use a practical example to describe how angular motion could be produced </li></ul><ul><li>2 marks </li></ul><ul><li>(May 2004) </li></ul>
  40. 40. Exam answer 2004 <ul><li>Use a practical example to describe how angular motion could be produced </li></ul><ul><li>2 marks </li></ul><ul><li>A force is applied off centre for angular motion to occur eccentric force applied outside centre of mass </li></ul><ul><li>Applied to a sporting example, e.g. player hits/kicks ball at side to create spin/curve </li></ul>
  41. 41. Learning Objectives <ul><li>To know and understand </li></ul><ul><li>Newton’s three laws of motion </li></ul><ul><li>The types of movement that can be produced </li></ul><ul><li>Be able to </li></ul><ul><li>Apply the laws of motion to explain the type of movement produced </li></ul><ul><li>Describe the effect of force in sporting actions </li></ul>
  42. 42. Home study <ul><li>Finish preparation for group presentation </li></ul><ul><ul><li>Any photocopying needs to be given to me by Thursday lunchtime at the latest </li></ul></ul><ul><ul><li>Bring any powerpoint presentations on a data stick or email them to yourself or me </li></ul></ul><ul><li>No review test next week </li></ul><ul><li>Complete exam questions </li></ul><ul><li>Reading in preparation for next lesson </li></ul><ul><ul><li>Centre of mass - Pages 52-55 </li></ul></ul>
  43. 43. Task As a group you must investigate and research the positive and negative impact of exercise on your disorder and deliver a 10 minute presentation/lesson to the rest of the group <ul><li>You must include: </li></ul><ul><li>A clear and detailed description of the disorder </li></ul><ul><li>How it is caused </li></ul><ul><li>Those at most at risk </li></ul><ul><li>Consider the positive and negative effects of different types of exercise, e.g. </li></ul><ul><ul><li>Low impact endurance </li></ul></ul><ul><ul><li>High impact </li></ul></ul><ul><ul><li>Repetitive actions </li></ul></ul><ul><ul><li>Contact activities </li></ul></ul><ul><li>A handout of key information for the rest of the class </li></ul><ul><li>A quick learning task at the end to test how well the group have understood </li></ul><ul><li>Be prepared to be asked questions at the end </li></ul><ul><li>Presentation could be poster or powerpoint based </li></ul><ul><li>Try to include pictures/videos </li></ul>
  44. 44. Where is the centre of mass? In a symmetrical/uniform object COM at geometrical centre Even distribution of mass around the centre
  45. 45. COM in humans <ul><li>Not uniform symmetrical shapes/composition </li></ul><ul><ul><li>Different heights, mass and compositions of fat, muscle, bone and tissue </li></ul></ul><ul><li>Centre of mass is not at a fixed point </li></ul>
  46. 46. Changes in centre of mass <ul><li>Location is also dependent on body position </li></ul><ul><li>Could be a point inside or outside the body </li></ul><ul><li>With movement centre of mass rarely stays in the same place </li></ul>
  47. 47. Where is the centre of mass?
  48. 48. The Fosbury Flop
  49. 49. Stability <ul><li>Factors that affect stability and balance in physical activity </li></ul><ul><ul><li>Position of athlete’s centre of mass </li></ul></ul><ul><ul><li>Position of the athlete’s line of gravity </li></ul></ul><ul><ul><li>Size of the athletes area of support </li></ul></ul><ul><ul><li>(Number of point in contact with the floor) </li></ul></ul><ul><ul><li>(Mass of the object) </li></ul></ul>UNSTABLE LESS STABLE STABLE
  50. 50. Stability <ul><li>How difficult it is to disturb a body from a balanced position </li></ul>
  51. 51. Stability Position of the athletes centre of mass
  52. 52. Stability Size of the athletes support area
  53. 53. Stability Position of an athletes line of gravity <ul><li>Line of gravity </li></ul><ul><li>A line extending from the centre of mass vertically down to the ground </li></ul>
  54. 54. Exam question (May 2008) <ul><li>Movement can be described as linear, angular or general motion </li></ul><ul><li>Use a practical example to describe how linear motion can be produced </li></ul><ul><li>2 marks </li></ul><ul><li>A force is applied through the centre of mass/gravity of the object. </li></ul><ul><li>A golfer/footballer must hit the ball through its centre of mass/gravity to ensure it travels in a straight line. </li></ul>Q1 & Q2
  55. 55. Exam question (May 2004) <ul><li>1 c During an analysis of practical activities, movement can be described as linear, angular or general motion </li></ul><ul><li>Use a practical example to describe how angular motion could be produced </li></ul><ul><li>2 marks </li></ul>
  56. 56. Exam answer 2004 <ul><li>Use a practical example to describe how angular motion could be produced </li></ul><ul><li>2 marks </li></ul><ul><li>A force is applied off centre for angular motion to occur eccentric force applied outside centre of mass </li></ul><ul><li>Applied to a sporting example, e.g. player hits/kicks ball at side to create spin/curve </li></ul>
  57. 57. Exam Question (May 2006) <ul><li>Describe how the position of the centre of mass can affect a balance. [3 marks] </li></ul><ul><li>Centre of mass must be over base of support to hold a balance </li></ul><ul><li>If Centre of mass moves close to the edge of the base of support balance becomes less stable </li></ul><ul><li>If Centre of mass/line of gravity passes outside base of support balance is lost </li></ul><ul><li>The lower the centre of mass the more stable the balance </li></ul><ul><li>If more points of balance are held balance is more stable </li></ul><ul><li>Large area of support makes balance more stable </li></ul>Q6a

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