Biomechanics exam chap 6

angular position

the orientation of a line with another line or plane

absolute angular position

one line or plan is fixed and immovable relative to the earth

absolute angular position example

angle between your thigh and the ground

relative angular position

both lines or planes are capable of moving, joint angle btwn segments

relative angular position example

joint angle, angle between thigh and shin

angular displacement

change in absolute angular position experienced by a rotating line, the angle between the final and initial angular position

range of motion (ROM)

anatomical displacement

specifying direction of angular displacement

clockwise, counterclockwise

must specify viewing position as clarification, always state when giving a direction

axis of rotation

real or imaginary line around which rotation occurs, aligned with a plane

always perpendicular to plane of motion

angular velocity

rate of change of angular position, how fast the body is rotating

instantaneous angular velocity

rate of rotation at an instant in time

if a point is farther from an axis

it will have greater distance and greater displacement

velocity

a vector, must specify both magnitude and direction

tangential linear velocity

how fast and in what direction the point is moving at an instant in time

angular acceleration

rate of change of angular velocity

starts, stops, speeds up, slows down, changes axis of rotaions

direction follows the right hand rule

angular acceleration: speeding up or starting

the direction of angular motion

angular acceleration: slowing down or stopping

the direction opposite of angular motion

angular acceleration: body is rotating faster (speeding up)

sign of velocity and sign of acceleration the same

angular acceleration: body is rotating slower (slowing down)

sign of velocity and sign of acceleration the opposite

tangential acceleration

component of linear acceleration tangential to the circular path

centripetal (radial) acceleration

component of linear acceleration to the center (radius) of the circular path

linear acceleration

occurs when an object slows down, speeds up, or changes direction

anteroposterior (AP) axis/ sagittal axis

cartwheel

transverse axis

somersaulting

longitudinal axis

twisting

circumduction

multiple-axis joint action around transverse and AP axis

segment motion forms a cone-shaped surface