© Tony Fagelman 2006 Coach Mechanics

© Tony Fagelman 2006 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

© Tony Fagelman 2006 Flight This is 2 nd part of any movement using the trampoline The flight requires control and phasing

© Tony Fagelman 2006 Landing Safety is a major factor Performer must be in control Preparation for next skill

© Tony Fagelman 2006 Newton’s Laws of Motion 1 st Law : –A body will continue in its uniform state of motion or rest unless acted on by an external force. 2 nd 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 3 rd Law: –For every action there is an equal and opposite reaction

© Tony Fagelman 2006 Centre of Mass The point though which the line of force of “attraction to the earth” takes place. Centre of Mass

© Tony Fagelman 2006 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

© Tony Fagelman 2006 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

© Tony Fagelman 2006 Displacement of COM What happens when we displace the Centre of Mass outside the body? Centre of Mass

© Tony Fagelman 2006 Mechanics of somersaulting Creation of a somersault Angular movement is caused by TORQUE Torque = Force x Perpendicular distance from axis of rotation COM Force Axis of rotation

© Tony Fagelman 2006 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

© Tony Fagelman 2006 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

© Tony Fagelman 2006 Axis of rotation somersault axis twisting axis side somersault axis Any rotation can be described using the 3 axis.

© Tony Fagelman 2006 Inertia The resistance of a body to change Inertia is measured by Mass Or Not… as the case may be

© Tony Fagelman 2006 Momentum Is the amount of Linear Movement “energy” in a body as it moves It is the “quantity” of motion –Velocity x Mass

© Tony Fagelman 2006 Speed Is the rate of movement of the Centre of Mass

© Tony Fagelman 2006 Conservation of Linear Momentum Conservation & Creation –Whatever you put into a closed system is what you have. Remember Newton’s 1 st Law Can a performer do anything to help themselves to safety if they do not have sufficient somersault rotation?

© Tony Fagelman 2006 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

© Tony Fagelman 2006 Moment of Inertia The measure of the body’s reluctance to start rotating (or change direction) around an axis

© Tony Fagelman 2006 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

© Tony Fagelman 2006 Angular Momentum The amount of rotational energy in a body as it rotates around an axis

© Tony Fagelman 2006 Changing Angular Momentum These are caused by external torques. The changes are determined by the size and direction of the torque

© Tony Fagelman 2006 Conservation of Angular Momentum Angular momentum will remain the same until changed by an external torque –Tucking when somersaulting –Straightening when somersaulting

© Tony Fagelman 2006 Early Twist Twist is initiated from the bed Arms are set whilst in contact with the bed. Movement is initiated Trampolinist has left the bed Arms are brought together to allow twist to continue

© Tony Fagelman 2006 Late Twist The Twist is initiated in the air –There are a number of theories given to this action.