Chapter Four : Kinematic Concepts of Human Movement Flashcards
General motion definition
Motion involving rotation and translation at the same time
Linear motion definition
Is the movement of a body along a straight or curved path where all body parts move in the same direction at the same speed
Linear distance definition
The path travelled by a body from point A to point B
Linear displacement definition
A change in the position of the body - how far from the initial to final position
Example of displacement vs. distance
When a runner completes 400m on a 400m track they have travelled 400m in distance but displacement is 0m as they are in the same position as they started
Linear speed definition
The ratio of the distance covered to the time taken
Linear speed equation
Speed = Distance(m)/Time(s)
Linear velocity definition
The ratio of displacement to the time taken. Velocity has both a size and a direction
Linear velocity equation
Velocity = Displacement(m)/Time(s)
Example of speed vs. velocity
When a ball is hit over a tennis net at a speed of 30m/s and returned at 30m/s in a different direction the speed remains the same but the displacement doesn’t as there is a change in direction
Linear acceleration definition
A change in velocity in a goven period of time
Acceleration equation
Acceleration = Change in velocity/Change in time
Acceleration values
Neg values means deceleration
Pos values mean acceleration
Zero means contant acceleration
Angular motion definition
Is a rotation around a central axis or fixed point
Axis of rotation definition
A straight line through all the points of a rigid rotating body
Where is axis of rotation?
External - the bar in a flip
Internal - When a ice skater turns vertically
Imaginary - when a person does a somersault ot is inside the somersault
Eccentric forces
A force applied at a perpedicular distance from the centre of gravity of an object. They cause objects to deviate from their original path
Example of an eccentric force
Torques
Torque equation
Torque = Force X Lever arm of the force
Torques and acceleration
The greater the torque the greater the angular acceleration
Factors affecting torque size
The length of the lever arm
The size of the applied force
Angular distance definition
Total of all angular changes of a rotating body
Angular displacement definition
The difference between the initial and final angular position of a rotating body
Example of angular distance vs. angular displacement
When a gymnast performs 1 1/2 flips around a bar she has travelled 540 degrees but the displacement is only 180 degrees as thats the change in position
