Coach

1. Coach Mechanics

2. Take-Off • Time is a major factor • Take-off is the most important part of any skill • Without a good take-off, the skill cannot be performed correctly

3. Flight • This is 2nd part of any movement using the trampoline • The flight requires control and phasing

4. Landing • Safety is a major factor • Performer must be in control • Preparation for next skill

5. Newton’s Laws of Motion • 1st Law : • A body will continue in its uniform state of motion or rest unless acted on by an external force. • 2nd Law: • The rate of change of momentum is proportional to the force causing it and the change takes place in the direction in which the force acts.force = mass x acceleration • if mass is constant, acceleration is proportional to the applied force • 3rd Law: • For every action there is an equal and opposite reaction

6. Centre of Mass • The point though which the line of force of “attraction to the earth” takes place. Centre of Mass

7. Forces • Push & Pull • A force is needed to: • Start a motion • Change the rate of motion • Change the direction of motion • Cause motion to stop

8. TORQUE • The Rotational push or pull • Caused by a FORCE • Eccentric or Off-Centre Force also called Torque • This will always create rotation • A torque whose line of action does not pass through the centre of mass of the body on which it acts

9. Displacement of COM • What happens when we displace the Centre of Mass outside the body? Centre of Mass

10. Mechanics of somersaulting • Creation of a somersault • Angular movement is caused by TORQUE • Torque = Force x Perpendicular distance from axis of rotation Force Axis of rotation COM Force

11. Linear Movement • Movement in a straight line • Remember Newtons’ 1st law • A body will carry on unless acted on • A trampolinist will bounce upwards until gravity pulls them back down again

12. Angular Movement • An off-centre force acting around the Centre of Mass will create angular movement (Somersault rotation) (Remember displacement of COM) • Rotation around an axis • Somersaulting demonstrates both Linear Movement and Angular Movement

13. Axis of rotation • somersault axis • twisting axis • side somersault axis Any rotation can be described using the 3 axis.

14. LBC Inertia • The resistance of a body to change • Inertia is measured by Mass • Or Not… as the case may be

15. Momentum • Is the amount of Linear Movement “energy” in a body as it moves • It is the “quantity” of motion • Velocity x Mass

16. Speed • Is the rate of movement of the Centre of Mass

17. Conservation of Linear Momentum • Conservation & Creation • Whatever you put into a closed system is what you have. • Remember Newton’s 1st Law • Can a performer do anything to help themselves to safety if they do not have sufficient somersault rotation?

18. Changing Linear Momentum • All changes in Linear momentum are caused by external forces. • The changes are determined by the size and direction of the force

19. Moment of Inertia • The measure of the body’s reluctance to start rotating (or change direction) around an axis LBC

20. Angular Speed • The rate of rotation around an axis • To control angular speed in flight (by changing the moment of inertia), the body can change shape

21. Angular Momentum • The amount of rotational energy in a body as it rotates around an axis

22. Changing Angular Momentum • These are caused by external torques. • The changes are determined by the size and direction of the torque

23. Conservation of Angular Momentum • Angular momentum will remain the same until changed by an external torque • Tucking when somersaulting • Straightening when somersaulting

24. Early Twist • Twist is initiated from the bed Trampolinist has left the bed Arms are brought together to allow twist to continue Arms are set whilst in contact with the bed. Movement is initiated

25. Late Twist • The Twist is initiated in the air • There are a number of theories given to this action.