Linear/Angular Motion Flashcards
What is kinematics?
Study of characteristics of motion
-Spatial and temporal
Why do we study kinematics?
Understand motion: joint movements and planes of motion
Optimise performance/ function
Minimise injury risk
How do we study kinematics?
Observation: 2D and 3D
How are scalars described?
By their magnitude:
Distance
Speed
Volume
How are vectors described?
By their magnitude and direction:
Displacement
Velocity
Acceleration
What is a vector?
Shortest distance from origin/ length of straight line joining initial and final positions
What is distance?
Length of path travelled
Speed equation
Time
Velocity equation
Displacement D
—————– = —
Time T
What is velocity?
The rate of change in displacement with respect to time
Velocity units
M/s
What is differentiation?
The Mathematical process that quantifies the rate of change in one variable with respect to another
What is instantaneous velocity?
The change in displacement with respect to time
What is equal to the gradient/slope of the displacement-time curve?
Differentiation
Integral of velocity = ?
Displacement
What is integration?
Quantities the total change of one variable with respect to another (reverse process of differentiation)
What is acceleration?
The rate of change in velocity with respect to time
Acceleration equation
T
Acceleration units
M/s2
What is an angle?
Composed of two lines that intersect at a point called the vertex
What is a relative angle?
Included angle between the longitudinal axes of two segments (joints)
What is an absolute angle?
Angle of inclination (orientation) of a body segment in space
What are the 3 units to measure angles?
Degrees
Revolution
Radian
Define degrees
Circle (describes rotation) transcribes an arc of 360*
What is a revolution?
*useful in qualitative analysis, performance descriptor
360* = 1 revolution
Define radian
The measure of an angle at the centre of a circle, described by an arc equal to the length of the radius of the circle
360* = 1 revolution = ?? Radians
2pie radians
Degrees to radians
Divide by 57.3
Radians to degrees
Multiply by 57.3
Radians =
Degrees x pie
—-
180
Degrees =
Radians x 180
——-
Pie
What is the right hand rule?
Curled fingers indicate direction of rotation
*thumb points in the direction of the angular velocity vector
What is polarity?
Refers to the direction of rotation of angular motion
Counter-clockwise: +ve polarity
Clockwise : -ve polarity
What is angular distance?
Total of all angular changes of rotating object
What is angular displacement?
Difference between the initial and final positions of the rotating object
What is angular speed?
Defined as angular distance travelled per unit of time
What is angular velocity?
Defined as change in angular displacement relative to change in time
Angular speed equation
Time
Angular velocity equation
Time
Angular velocity units
rad.s*1
What is angular acceleration?
The rate of change in angular velocity over time
Angular acceleration equation
T
Angular acceleration unit
rad.s*2
What is angular-linear motion?
In many human movements, motions of the segments constituting the movement are ANGULAR – resulting movement is LINEAR
Tangential velocity
.. Of the ball is dependent upon the length of the arm segment and its angular velocity
Tangential velocity equation/unit
V
t = r. w
M.s*1
Tangential acceleration
… Of the bowling ball is dependent upon the length of the arm segment and its angular acceleration
*a vector tangent that is perpendicular to the rotating segment
Tangential acceleration equation/unit
a
T = r a
M.s*2
