KEY KNOWLEDGEKEY SKILLS  The different parts that make up levers including the axis, force and resistance arms and how they relate to movements  How do centre of gravity, base of support, line of gravity and mass affect the balance and stability of objects and sportspeople?  Explain the application of key biomechanical principles to a range of sporting movements by using correct terms  Investigate and interpret graphs of biomechanical principles pertaining to movements in sports and activities.  Participate in, analyse and report on a range of practical activities that consider biomechanical principles  Use biomechanical principles to critique the effectiveness of different movements  Analyse different sporting actions to identify similarities and differences as well as the correct application of biomechanical principles to improve performance

Torque is the rotary effect caused by an eccentric force. The lever arm is the perpendicular distance from the axis of rotation to the force’s line of action.

Sometimes more than 1 force acts on a body When the forces acting on a body are equal but applied in opposite directions they create a force couple Force couples produce torque and the object will rotate about its axis of rotation. Force Couple

Exists when there are no unbalanced forces or torques acting on an object. Two types of equilibrium:  Static Equilibrium ◦ An object that is motionless ◦ Cannot be moving or rotating.  Dynamic Equilibrium ◦ An object moving with constant velocity (not accelerating) ◦ Moving at a constant velocity.

 Stability: ◦ Resistance to the disruption of equilibrium ◦ Increased stability = more difficult to unbalance ◦ Decreased stability = less difficult to unbalance  Balance: ◦ The ability to control equilibrium

 Body mass ◦ Greater mass = greater force required to move it.  Friction between the body and the surface ◦ Increase friction = increases stability ◦ Decrease friction= decreases stability  Base of support ◦ Larger base of support = greater stability  Position of centre of gravity ◦ Higher = less stable ◦ Lower = more stable ◦ Above base of support = more stable

 For a solid object, such as a ball or cricket bat the COG remains at a constant position.  For objects which change shape, such as humans, the COG changes depending on the object’s current shape.  The following rule can be used to estimate the COG of a human (it is only a general rule):  Adult male: COG is approx 2.5cm below navel, or 57% of their height.  Adult female: COG is approx 55% of their height.  Child: the COG is approx 60% of their height.

 Page 125  Questions 1 - 5

 “Rigid bar-like objects that turn about a fixed point (fulcrum) and to which forces are applied at two other points.”  Three types of levers. All three have three main elements: 1.A force 2.A resistance 3.An axis, fulcrum or pivot point

 Generate moderate levels of speed and strength.  The axis of rotation (fulcrum) is in between the resistance and force.

Force downwards Fulcrum (pivot point) Resistance

First-class levers - resistance and force are on either side of the axis

 Used to generate strength.  Have a resistance between the fulcrum and the force.

Fulcrum (pivot point) Resistance Force

Second-class levers – resistance occurs between the force and axis

 Used to generate speed.  Have a force between the fulcrum and resistance.

Third class levers Fulcrum (pivot point) Resistance Force

Third-class levers – force between the resistance and the axis

 Principle of leverage: ◦ Velocity is greater at the end of a long lever than at the end of a short lever. The longer the lever, the greater the velocity at impact and the greater momentum developed by the object. However, what do we know about longer levers?

 How could the length of the lever have a negative impact on a sportsperson’s performance?

 Page 131  Questions 1 - 4

 Choose a sport that you a familiar with.  Apply each biomechanical principle that we have discussed using an example from your chosen sport.

 External forces  Internal forces ◦ (isometric & isotonic)  Sub-maximal forces  Force summation (maximal force)  Inertia  Momentum  Impulse  Levers (1 st, 2 nd & 3 rd class)  Motion (linear, angular & general)  Moment of inertia  Angular momentum  Projectile Motion ◦ Speed and velocity of release ◦ Angle of release ◦ Height of release ◦ Spin  The Magnus Effect  Coefficient of Restitution  Friction (rolling and sliding)  Balance & stability