acrobatics
Goals:
- Maximize angular velocity
- Maximize momentum (angular & linear)
Biomechanical Factors:
1) Angular momentum is conserved and cannot be changed (unless there is an external force that can cause torque)
2) Linear momentum = velocity x times
3) Angular momentum = angular velocity x moment of inertia
Resistance to starting or stopping a spin/rotation · dependent on mass and distance of mass (radius) from axis
· eg: arms and legs tucked tightly to body or extended out and away while spinning on a chair
Types of Angular Momentum
Torque Twist--angular momentum produced at push-off *most efficient
Non-Torque Twist
-Hula Twist--spin produced by making a circular motion with body/extremity
-Tilt Twist--movement of one body part that creates spin around a different axis
-Cat Twist--progressive rotation about an axis as a result of increases and decreases in the distance of mass from the axis
Critical Features: (diving example)
-Perpendicular entry and no splash
-Form
-Maximum starting momentum to allow for greater time in air o Ride board to the peak of its spring
o Deep countermovement allowing for greater extension
-Maximum angular momentum for quickest completion of skill (torque twist around COM)
o Push-off angle/ torque around COM
o Establish tight tuck at peak of flight
o Tuck head in
o Maintain tight tuck until lay-out
-Timing of lay-out to slow momentum of inertia for perpendicular entry
o Extend legs and arms completely
Observation Plan: (forward roll)
Watching from side of tumbler
Push-Off
· Feet together
· Full leg extension
· Forward push-off
· Head tucked
· Hands placed evenly
Roll
· Heels snap to butt
· Body stays tucked
· Arms are thrown forward
· Rolling in straight line
Stand
· Heels hit mat just in front of butt simultaneously
· Tuck is held until shoulders past knees
· Arms thrown forward overhead—fully extended
· Hips/knees extended quickly to counteract forward momentum
see the subpage for an acrobatics observation & evaluation!
1) Angular momentum is conserved and cannot be changed (unless there is an external force that can cause torque)
2) Linear momentum = velocity x times
3) Angular momentum = angular velocity x moment of inertia
Resistance to starting or stopping a spin/rotation · dependent on mass and distance of mass (radius) from axis
· eg: arms and legs tucked tightly to body or extended out and away while spinning on a chair
Types of Angular Momentum
Torque Twist--angular momentum produced at push-off *most efficient
Non-Torque Twist
-Hula Twist--spin produced by making a circular motion with body/extremity
-Tilt Twist--movement of one body part that creates spin around a different axis
-Cat Twist--progressive rotation about an axis as a result of increases and decreases in the distance of mass from the axis
Critical Features: (diving example)
-Perpendicular entry and no splash
-Form
-Maximum starting momentum to allow for greater time in air o Ride board to the peak of its spring
o Deep countermovement allowing for greater extension
-Maximum angular momentum for quickest completion of skill (torque twist around COM)
o Push-off angle/ torque around COM
o Establish tight tuck at peak of flight
o Tuck head in
o Maintain tight tuck until lay-out
-Timing of lay-out to slow momentum of inertia for perpendicular entry
o Extend legs and arms completely
Observation Plan: (forward roll)
Watching from side of tumbler
Push-Off
· Feet together
· Full leg extension
· Forward push-off
· Head tucked
· Hands placed evenly
Roll
· Heels snap to butt
· Body stays tucked
· Arms are thrown forward
· Rolling in straight line
Stand
· Heels hit mat just in front of butt simultaneously
· Tuck is held until shoulders past knees
· Arms thrown forward overhead—fully extended
· Hips/knees extended quickly to counteract forward momentum
see the subpage for an acrobatics observation & evaluation!