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
Angular speed definition
Is the angular distance covered divided by the time taken to complete the motion
Angular velocity definition
Is the rate of change of the angular displacement of a body over time.
Angular speed equation
Angular speed = Angular distance/ Time
Angular velocity equation
Angular velocity = Angular displacement/ Time
Example of angular speed vs. angular velocity
If a gymnast took 3 seconds to complete 1 1/2 rotations
- angular speed is 180 degrees per second
- angular velocity is 60 degrees per second
Relationship between the linear and angular velocity
Linear velocity = Radius of rotation X Angular velocity
Angular acceleration definition
Is the rate of change of angular velocity, how quickly a body changes angular position. Measured in degrees/seconds^2
Projectile definition
An airborne body that is only affected by the forces of gravity and air resistance
Components of a flight path
Vertical
Horizontal
The vertical component of projectile motion
Influenced by gravity and height of release
Vertical speed if an object decreases as it goes up and increases as it goes down.
If an object is released and stopped at the same height the speed will be the same
The horizontal component of projectile motion
Influenced by air resistance and horizontal velocity
Without air resistance, an object would travel at the same velocity horizontally continuously
Factors affecting the path of a projectile
Angle of release
Speed of release
Height of release
What factors impact flight time?
Initial vertical velocity
Height of release
Angle of release definition
Is the angle at which the object is projected into the air
Types of trajectory in angle of release
Vertical - at an angle of 90 degrees, goes straight up and down
Oblique trajectory - an angle between 0 and 95 degrees, causes a parabolic curve.
Horizontal trajectory - at an angle < 0 degrees, creates a downhill line
What is the best angle of release to get the furthest distance?
45 degrees
Speed of release definition
The speed at which an object is thrown, kicked or propelled into the air
The vertical component of speed of release
Impacts height of projectile and flight time of projectile
The horizontal component of speed of release
Impacts distance travelled
Height of release definition
Is the difference between the height that a projectile is released and the height at which is stops
Correct angle of release for the relative projection height
Height of release = 0, the best angle is 45 degrees and will get the furthest throw
Height of release > 0, the best angle <45 degrees
Height of release < 0, the best angle is >45 degrees.
Examples of correct release angles for sports
Long jump - 15-27 degrees
High jump - 40-48 degrees
Shot put - 36-37 degrees
