Introduction to Kinematics

Question 1

What is kinematics?

Answer 1

The study of the description of motion without regard to the motion causes.

Question 2

What are the four variables of kinematics?

Answer 2

Linear displacement
Linear velocity
Linear acceleration
Angular displacement

Question 3

What is linear displacement?

Answer 3

Straight line distance from start to finish.

Question 4

What is the symbol for linear displacement?

Answer 4

s

Question 5

What is the unit for linear displacement?

Answer 5

m

Question 6

What is linear velocity?

Answer 6

Rate of change of displacement with respect to the change in time

Question 7

What is the symbol for linear velocity?

Answer 7

v

Question 8

What is the unit for linear velocity?

Answer 8

m/s

Question 9

What is linear acceleration?

Answer 9

Rate of change of velocity with respect to the change in time

Question 10

What is the symbol for linear acceleration?

Answer 10

a

Question 11

What is the unit for linear acceleration?

Answer 11

m/s²

Question 12

What is angular displacement?

Answer 12

Angular distance from start to finish

Question 13

What is the symbol for angular displacement?

Answer 13

° or θ

Question 14

What is the unit for angular displacement?

Answer 14

Degree radias

Question 15

What is distance?

Answer 15

A scalar quantity, so only contains magnitude which is length of path travelled by an object measured in metres

Question 16

What is displacement?

Answer 16

A vector which contains both magnitude and a direction measured in metres.

Question 17

What is an example of distance measured?

Answer 17

Total distance travelled by a footballer in a match, this monitors workload

Question 18

What is an example of displacement measured?

Answer 18

Long jump - horizontal distance jumped

Question 19

What is speed?

Answer 19

A scalar quantity, so only contains magnitude, measured in m/s

Question 20

What is velocity?

Answer 20

A vector, so contains a magnitude and a direction, measured in m/s

Question 21

What is the equation for velocity?

Answer 21

Change in displacement / change in time

Question 22

What is acceleration?

Answer 22

A vector, so contains a magnitude and a direction, measured in m/s²

Question 23

Give an example of angular kinematics.

Answer 23

Release angle shot put, optimum around 37°

Question 24

What is motion capture?

Answer 24

The process of recording the movement of people or objects and is a method to obtain kinematic data.

Question 25

What devices allow us to detect different phases of movement?

Answer 25

Optical systems
Accelerometers
Cameras

Question 26

What devices allow us to detect segment and joint positions?

Answer 26

Accelerometers
Electrogoniometers

Question 27

What are different types of motion capture?

Answer 27

Optical systems
2D video
Goniometer
Wearables
3D motion analysis

Question 28

What do optical systems measure?

Answer 28

Spatiotemporal variables

Question 29

What are the pros of optical systems?

Answer 29

Easy to use and set up
Give results instantly - performance profiling and monitoring
No interference to athlete

Question 30

What are the cons of optical systems?

Answer 30

Only spatiotemporal variables
Only suitable for gait, running and jumping

Question 31

What are the pros of 2D video?

Answer 31

Easy to use and set up
Cheap
No interference to athlete, can use in competition with organiser permission

Question 32

What are the cons of 2D video?

Answer 32

Need to manually digitise, time consuming and less accurate
Only 2D = one plane of movement

Question 33

What are the pros of a goniometer?

Answer 33

Simple output - joint angle
Easy to use and set up
Relatively cheap
Minimal interference to athlete

Question 34

What are the cons of a goniometer?

Answer 34

Joint angles only
Not linked to other equipment

Question 35

What are wearables?

Answer 35

Activity and workload monitoring, in-field data collection and during daily living

Question 36

What are the pros of wearables?

Answer 36

Easy to use and set up
Relatively cheap
Very little interference to athlete

Question 37

What are the cons of wearables?

Answer 37

Typically simple metrics, distance travelled, time in workload zones (speed), jump heights, accelerations

Question 38

What is a marker based 3D motion capture?

Answer 38

Requires a minimum of 2 cameras to track a marker in 3D

Question 39

What are the pros of a marker based 3D motion capture?

Answer 39

Gold standard - very accurate
3D data
Automated tracking and trajectories. for some applications produce automated reports
Can be integrated with other equipment (force plates, EMG)

Question 40

What are the cons of a marker based 3D motion capture?

Answer 40

Generally lab only
Time consuming to set up equipment and participant
Expensive £100,000
Limited capture volume

Question 41

What are the pros of a markerless IMU 3D motion capture?

Answer 41

3D data
Easy to use, attach IMU’s to participant
Can be integrated with other equipment (force plates, EMG)
Larger capture volume if good wifi signal

Question 42

What are the cons of a markerless IMU 3D motion capture?

Answer 42

Use algorithms to calculate joint angles and angular velocities from accelerometer, goniometer and magnetometer data in IMUs - based on normal kinematics
Can suffer interference from electrical cables/motors and metal
Expensive £100,000
Can suffer drift in longer trials
Can’t use in competitions

Question 43

What are the pros of a markerless 3D motion capture video?

Answer 43

3D data
No interference to the athlete, no markers
Can be integrated with other equipment (force plates, EMG) with certain systems

Question 44

What are the cons of a markerless 3D motion capture video?

Answer 44

Use algorithims to fit skeleton to video image, trained on a normal population
Expensive, software £30,000 + cameras
Limited capture volume