1. You will learn the following
Stability & Balance
1) centre of gravity
2) line of gravity
3) base of support
Newton’s 3 laws of motion
1st Law of Inertia
2nd Law of Acceleration
3rd Law of Action/reaction
Force summation
Levers
Projectile motion

2. Stability & Balance

3. Support Accurately Balance controlling Stability is defined as:
Maintaining stability and _________ during sporting situations/performance has a number of benefits. It allows a person to put more force into a movement and complete that movement ____________ and with control. Achieving balance and stability involves ______________ your centre of gravity, line of gravity and base of _________.
Support Accurately Balance controlling
Stability is defined as:
The ability to hold or maintain a position in space

4. Answers
Maintaining stability and balance during sporting situations/performance has a number of benefits. It allows a person to put more force into a movement and complete that movement accurately and with control. Achieving balance and stability involves controlling your centre of gravity, line of gravity and base of support.

5. Principle 1
the closer the line of gravity is to the centre of the base of support, the greater the probability of maintaining balance
Principle 2
the broader the base of support, the greater the probability of maintaining balance
Principle 3
the probability of maintaining balance increases when the COG is lowered in relation to the BOS
Principle 4 the further one body part moves away form the line of gravity, the probability of maintaining balance decreases unless another body part moves to compensate for it.

6. Principles of stability and balance
the closer the line of gravity is to the centre of the base of support, the greater the probability of maintaining balance
Line of gravity

7. Principles of stability and balance
Principle 2 the broader the base of support, the greater the probability of maintaining balance
Base of support

8. Principles of stability and balance
Principle 3 the probability of maintaining balance increases when the COG is lowered in relation to the BOS
Bending his knees to be more balance

9. Principles of stability and balance
Principle 4 the further one body part moves away form the line of gravity, the probability of maintaining balance decreases unless another body part moves to compensate for it.

10. Stability and Balance
There are three concepts of stability and balance…
1) Centre of gravity (COG)
2) Line of gravity (LOG)
3) Base of support (BOS)

11. Centre of Gravity
The point at which all parts of the body/object are equally balanced

12. Determining the Centre of Gravity
Box Method
Where you draw a box around the object and draw diagonal lines in the shape of an X inside the box, the point at which the two lines cross is the COG.

13. When we stand in the anatomical position, our COG is located around the hip region.

14. Line of Gravity
Is the vertical line that passes through the centre of gravity to the ground. This line can fall outside of the body if it is on an angle.

15. Base of Support
The area within an object’s point of contact with the ground. The larger the area the base of support covers, the more stable an object will be. The persons feet are normally their BOS.

16. BOS is the area within an objects point of contact with the ground
BOS is the area within an objects point of contact with the ground. The larger the area the base of support covers, the more stable an object will be.
Wide BOS
Narrow BOS
BOS
BOS
Base of support – The object on the left is more stable because of its relatively larger BOS

17. The picture on the left has a ________Base of support and therefore is more balanced than the picture on the right. The picture on the right has a small _________________ as her feet are close together, which means she has less balance than the picture on the left.

18. Line of gravity Line of gravity Line of gravity Centre of gravity
STABLE
UNSTABLE
Line of gravity

19. Increasing stability and balance
To increase the stability and balance of a person you can do the following things
Widen the base of support by putting feet shoulder width apart and having as many body parts in contact with the ground at once.
Lowering the centre of gravity by bending knees (to get closer to the ground)

20. What other factors can increase stability?
1) Increase friction with the playing surface eg- spikes or sprigs on boots
2) Lean into an oncoming force eg- leaning into an oncoming tackle in rugby or league
3) Increase rotation eg- you are more stable on a bike moving than one standing still
4) Increase mass eg- a larger person is harder to move because they have more inertia

21. Revision

22. 1) Which item on my foot with give me the biggest Base of Support (BOS) and Why?
Ice skates Flippers/Fins Sports shoes Rugby boots canvas shoes
2) Which item from the list above would give me the smallest Base of Support (BOS) and why?
3) Define Centre of Gravity (COG)
6) If i want to lower my COG what can i do?

23. Define the following terms
1) BOS-
2) LOG-
3) COG-

24. Can you apply the principles of balance to a rugby player about to be tackled.

25. How can we make the following situations more stable?

26. Applying the Theory of Balance
Why does this not fall over?

27. Because LOG falls inside the base of support

28. Sporting Examples for each
Principle 1
Principle 2
Principle 3
Principle 4

29. Who is more balanced? Why?

30. How do these people remain balanced?

31. Newton’s Laws Newton’s First Law – Inertia
Newton’s Second Law – Acceleration
Newton’s Third Law – Action/Reaction

32. Newton’s First Law

33. Newton’s 1st Law of Inertia
An object at rest tends to remain at rest unless acted upon by some external force.
What’s the external force?

34. Newton’s 1st Law of Inertia
That means that if an object is moving, it tends to keep going unless something stops it, like friction or gravity or this guy.

35. Newton’s 1st Law of Inertia
It also means that an object that is not moving stays put unless something hits it, pushes it, or pulls it.

36. How does Newton's 1st law apply to a basketball jump shot?
Question
How does Newton's 1st law apply to a basketball jump shot?

37. Newton’s 2nd Law

38. Newton’s 2nd Law of Acceleration
Newton’s Second Law – Acceleration
When a force acts upon a mass, the result is acceleration of that mass
(F = m x a)

39. Newton’s 2nd Law of Acceleration
*The harder you hit the ball, the faster and possibly further it will travel.
*Or the softer you hit the ball, the slower and less further it will travel.
*The mass will accelerate in the direction the force is applied

40. How does Newton's 2nd law apply to a basketball jump shot?
Question
How does Newton's 2nd law apply to a basketball jump shot?

41. Newton’s 3rd Law

42. For every action, there is an equal and opposite reaction.
Newton’s 3rd Law
For every action, there is an equal and opposite reaction.

43. Newton’s 3rd Law

44. How does Newton's 3rd law apply to a basketball jump shot?
Question
How does Newton's 3rd law apply to a basketball jump shot?

45. 1st Law – the ball will remain at rest until a force is applied to it.
Summary
1st Law – the ball will remain at rest until a force is applied to it.
2nd Law – the greater the force applied, the greater the acceleration of the ball.
3rd Law – the runner applies an action force on the ground and the ground applies a reaction force back.

46. FORCE SUMMATION

47. Force Summation
To give an object momentum in activities such as throwing, kicking or striking an object, the amount of momentum given to the object is determined by ‘the sum of all forces generated by each body part’ (i.e. Force summation).

48. Force Summation
To gain maximum momentum, the force needs to be generated by:
Using as many segments of the body as possible.
In the correct sequence, using large muscles first and then the smallest muscles last but fastest.
With correct timing.
Through the greatest range of motion.

52. To achieve maximum force in the “Block” in the game of basketball the athlete needs to lead with there ____________ then this follows through to their ____________/___________ and finally with the _____________ as they extend up to block the ball coming onto their side of the court.
Arms Legs Trunk/back

53. If you wanted to shoot a 3 pointer in basketball, list the order of muscles (by group, not by individual muscles) that would be used in order to play this shot with correct force summation ________ _________ _______ ________ _________ _______ Lower arm, shoulder, lower legs, back/trunk, upper arm, upper legs 1

54. Highlight which answer is correct below…
A) force summation is the process of using smaller muscles to bigger muscles in the correct timing order to create the greatest force
B) force summation is the process of using bigger muscles to smaller muscles in the correct timing order to create the greatest force

55. Answer
B) force summation is the process of using bigger muscles to smaller muscles in the correct timing order to create the greatest force

56. FORCE SUMMATION LAB Complete force summation lab in 4’s-5’s. Equipment
measuring tape/ and ball
Task
Throw the ball sitting down
Throw the ball standing up
Throw the ball using a step and throw

57. Question?
To achieve maximum power in a punch the legs and the trunk leads the movement. Explain why?

58. Question?
E.g. the bigger stronger muscles of the upper body/trunk initiate the movement followed by the muscles of the upper arm and finally the lower arm. To gain maximum force in the cross punch all muscles will be used. The muscles need to be used sequentially. The entire movement must be completed over a stable base as this will ensure maximum force.

59. SUMMARY To gain maximum momentum, the force needs to be generated by:
Using as many body parts as possible.
In the correct sequence (use large muscles first & then the smallest muscles last but fastest).
With the correct timing.
Though the greatest range of motion.

60. Revision

61. What does this relate to.....

62. Revision Questions
Fill in the blanks with the words down the bottom....
The more involved, the greater the force or generated. (eg. A shot-putter should use the legs, hips, ----, shoulders, arms, and in order for maximum distance.
speed, wrist, back, body segments

63. Revision Questions
The more body segments involved, the greater the force or speed generated. (eg. A shot-putter should use the legs, hips, back, shoulders, arms, and wrist in order for maximum distance.

64. Revision Questions Fill in the blanks with the words on the bottom...
To gain maximum , the force needs to be generated by:
Using as many ---- parts as possible.
In the correct sequence (use muscles first & then the muscles last but fastest).
With the timing.
Though the greatest range of
momentum, large, body, smallest, correct, motion

65. Revision Questions Using as many body parts as possible.
To gain maximum momentum, the force needs to be generated by:
Using as many body parts as possible.
In the correct sequence (use large muscles first & then the smallest muscles last but fastest).
With the correct timing.
Though the greatest range of motion.

66. Revision Questions
To achieve maximum power in a set, the legs leads the movement. Explain why?

67. Force of Summation
The bigger stronger muscles of the lower body in the legs eg- hamstrings and quadriceps initiate the movement followed by the muscles of the trunk/back then the upper arm and finally the lower arm. To gain maximum force in the set all muscles should be used, The muscles need to be used sequentially. The entire movement must be completed over a stable base as this will ensure maximum force, i.e. both feet on the ground.

68. List the order of joints then muscles used for force summation
knee, wrist, back/trunk, ankle, , shoulder, elbow, hip,

69. Revision
Come up with sporting examples that could be used for each of Newton’s Laws...
Three sporting examples for each...

70. Projectile Motion

71. What is projectile?
Projectile -As soon as an object is thrown it becomes a projectile.

72. What is Projectile Motion?
Projectile motion is the curved path that an object follows when thrown, or launched

73. Yes Examples
Non Examples
Tennis ball
Football
Golf ball
Basketball
Javelin
Jumping out of a car
Cannon ball
Plane
Rocket
Missile

74. An object moving in projectile motion has two components:
Horizontal
Vertical

75. Consider a pitcher throwing a baseball:
After the ball leaves the pitcher’s hand, the ball’s
horizontal velocity is constant.
b) The ball’s vertical velocity
increases because gravity causes
it to accelerate downward.
c) The two motions
combine to form a
curved path.

76. How to throw an object further...
Change the...
Height of release (the higher the better).
Speed of release (the faster the better).
Angle of release (45° for optimum distance).

77. Factors Affecting Projectile Motion
Speed of Release
Generally, the greater the speed of release, the greater the distance gained.
Direction of Flight
Initial Vertical Velocity
Initial Horizontal Velocity

78. Factors Affecting Projectile Motion
Angle of Release
In sporting situations the angle of release is usually always lower, around 35° to 45°.

79. Factors Affecting Projectile Motion
Height of Release
The greater the height of release the greater the distance gained, why?
Time in the air will be greater.
Would this mean that Mr Rameka (The Great) could throw a ball at the top of a hill would hit it further than at the bottom of the hill? Why?

80. Yes the ball will stay in the air longer so will have a greater chance to fly further. This assumes the same club and force is used.
Height of release

81. Levers

82. What are levers? Mechanical devices.
Help with movement about a fixed axis.

83. Functions of levers… Help muscles to move larger weights.
Increase the speed that a body can move at.

84. Levers in the human body
Bones = levers.
Joints = fixed axis - FULCRUM
Muscles = move levers - EFFORT
Limb/weight = anything heavy-LOAD

85. The 3 Types of lever First Class Lever Second Class Lever
Third Class Lever
Each is classified by the relationship between the Fulcrum (F), Load (L) and Effort (E).

86. First Class Lever Fulcrum lies in the middle of the effort & load…

87. Examples of first class levers…
Nodding your head.

88. First class levers in sport…

89. How do 1st class levers help us to move?
Help joints to move quickly – e.g. the javelin throw.
AND
Helps with moving heavy weights – e.g. whilst rowing.

90. Second class lever Load lies in the middle of the fulcrum & effort…

91. Examples of a second class lever…
Standing on tiptoe.

92. Second class levers in sport…

93. How do 2nd class levers help us to move?
Generates large amounts of force (Strength).

94. Third class levers Effort lies in between the fulcrum and the load…

95. Examples of a third class lever…
Bicep curl.

96. Examples of 3rd class levers in sport…

97. How do 3rd class levers help us to move?
Most common type of lever in the human body.
Helps to increase the speed of movement.

98. Why 3rd class levers are the most useful…
Move loads a large distance with only a small movement of the effort arm.
A wide range of movements are possible.
Increases speed of the body/lever system.
BUT – only light loads can be moved.
Due to the shortness of the effort arm.

99. An easy way of remembering…1 L 2 E 3

100. Mechanical Advantage…
How efficient a lever system is.
i.e. when a lever system puts out more force than it puts in.
Depends upon the lengths of the resistance (load) & effort arms…

101. Effort Arm… E L Part of the lever between F & E.
Long effort arm = less effort needed to move a force.
The ball of your foot.
MECHANICAL ADVANTAGE E L

102. Resistance Arm… L E Long resistance arm = great speed.
Part of the lever between F & L.
Long resistance arm = great speed.
E.g. Lacrosse
MECHANICAL DISADVANTAGE L E

103. Revision

104. Summation of Forces
In a tennis serve, describe what muscles are used and in what order they are recruited?
Core
Hips
Deltiods
Shoulder
Wrist/Hand muscles
The force used to hit the ball is a combination of all the individual muscle firing in sequence.
For your own sport choose a specific skill and list the order of muscles that are recruited.

105. Principle #1
What happens as we move the line of gravity closer to the edges of the base of support? X

106. We become more unstable and the chances of losing balance increases, when we move the line of gravity closer to the edges of the BOS.

107. Questions Write down 5 sporting examples of Inertia
A stationary soccer ball resting on the pitch .

108. Mix and match For every action there is an equal and opposite reaction
Action/ Reaction
Inertia
Acceleration
For every action there is an equal and opposite reaction
3rd law
An object at rest tends to remain at rest until acted upon by an external force
1st law
When a force acts upon a mass, the result is acceleration of that mass
2nd law

109. Using the photos below and your knowledge of force summation, explain how force is applied in a volleyball serve.

110. Revision
Come up with sporting examples that could be used for each of Newton’s Laws...
Three sporting examples for each...

111. Revision
1st Law – Soccer free kick, hitting a golf ball, rugby conversion
2nd Law – Golf/cricket/tennis –
swinging a club slowly with force gives the ball less momentum
3rd Law – running, dribbling a basketball, jumping

112. So, the law is as follows:
Soft action - __________ reaction
Hard action - __________ reaction

113. Which of the following is the MOST STABLE?

114. A is the most stable because:
They have the lowest centre of gravity
They have the largest base of support
And like C their centre of gravity is in the centre of the base of support X
The LARGER the area of your Base of Support, the MORE STABLE you will be

115. Match each statement with the correct Law
Match each statement with the correct Law..... Without looking at your notes.
1st Law
2nd Law
3rd Law
The runner applies an action force on the ground and the ground applies a reaction force back.
The ball will remain at rest until a force is applied to it.
The greater the force applied, the greater the acceleration of the ball.

116. Which Law is this?

117. The Tennis Serve – done correctly!

118. The Tennis Serve – done incorrectly!