Linear Kinematics 1

Question 1

How is Kinematic data collected

Answer 1

• Motion analysis systems (passive or active marker system)

- Accelerometers

Question 2

How active and passive marker systems work

Answer 2

Active - emit infrared light back to the capture system

Passive - markers are reflective and place on the body

Question 3

Sampling frequency video speeds (FPS)

Answer 3

Normal – 50,100Hz
High speed - 120,230,500,1000Hz

Pick the most suitable for the movement to capture the right about of information

Question 4

Digitisation explained (Qualitive –> quantitative)

Answer 4

• Gives selected points numerical values allowing joint displacements & anatomical landmarks to be determined
• allows for subsequent velocity/acceleration calculations

Question 5

Digitisation graphs key points

Answer 5

• Plot data onto graph for clarity
• Use reference system eg X,Y coordinates
• Add scale to give real units for analysis
• Calculate distance/speed changes

Question 6

4 main variables used to describe linear motion

Answer 6

• Position (location in space to a reference)
• Distance (length of path travelled, scalar,)
• Displacement (distance between start & finish, vector)
• Velocity/acceleration (rate of change in position & direction, vector)

Question 7

Time (temporal) analysis

Answer 7

• eg time of 100m sprint, ‘swing’ time in running, ground contact time
• combined with digitisation for analysis

Question 8

Speed equation

Answer 8

Speed = distance / time

Question 9

Velocity equation

Answer 9

Velocity = displacement (change) / time (change)

Question 10

Acceleration equation

Answer 10

Acceleration = velocity (change) / time (change)

Question 11

What negative acceleration and velocity values means

Answer 11

negative velocity = moving in opposite direction to previous frame/movement
negative acceleration = decelerating