angular motion Flashcards
angular motion
- The movement of a body or part of a body in a circular path around an axis of rotation
- Results from an eccentric force being applied to a body
- where the force is applied outside the centre of the body’s mass
example of angular motion
e.g. the whole body of a gymnast swinging on the asymmetrical bars will move in a circular path with her hands in contact with the bar = becomes axis of rotation
e.g. the forearm in a bicep curl moves in a circular motion around ht elbow joint = axis of rotation
eccentric force/ torque
torque (turning/ rotational force)
planes + axis
- sagittal plane (side+side), transverse axis (through hip)
= flexion + extension - transverse plane (top+bottom), longitudinal axis (through top of head vertically)
= rotation - frontal plane (front+back), frontal axis (through belly button)
= abduction + adduction
angular velocity
- (speed of rotation)
= measured in radians per second (rad/ s), 360 degrees = 2 pi radians, angular distance or angular displacement = radians
= the rate of change in angular displacement or RATE OF ROTATION,
- angular displacement/ time taken
moment of inertia
a sum of (mass x distribution of mass from the axis of rotation), kgm^2, the resistance of body to change its state of angular motion/ rotation
two factors affecting moment of inertia
- mass
- distribution of mass
mass
High moment of inertia, high reluctance to rotate, rotate slower/ more difficult
distribution of mass
- Closer limbs/ tucked in to axis, rotate quicker, lower distribution of mass, less air resistance, less reluctant to change
angular momentum
quantity of rotation, angular velocity x moment of inertia, kgm^2 rad/s
angular distance
the total length of the angular path covered from one position to another, rads
angular displacement
the shortest straight-line angular route from start to finish, rads
angular speed
the rate of change in angular distance, rads/ second
