1. Angular Motion Biomechanics

2. 2 Angular motion During free rotation – angular momentum remains constant This situation occurs when somersaulting and twisting during flight and during ice- skating spins (ignore friction)

3. 3 Angular momentum is the Angular momentum = Angular velocity = Moment of inertia = Angular Momentum quantity of rotation angular velocity x moment of inertia rate of rotation or spin spread of body’s mass

4. 4 Constant angular momentum If you change the moment of inertia; then the also changes Tuck body up small to moment of inertia and angular velocity Seen during and angular velocity lower increase somersaults ice-skating spins

5. 5 Typical question Explain the mechanical principles that allow spinning ice-skaters to adjust their rate of spin.(6 marks)

6. 6 Answer Ice may be regarded as a friction free surface/friction is negligible; During spins angular momentum remains constant; Angular momentum is the quantity of rotation; Angular momentum = angular velocity x moment of inertia; Angular velocity = rate of spin/how fast skater spins; Moment of inertia = distribution/spread of mass around axis; Changing/reducing moment of inertia affects/increases angular velocity; Skater brings arms into body allowing rate of spin to increase; (Accept annotated diagrams/graphs)6 marks