Angular Motion

Question 1

Definition of angular motion

Answer 1

When a body/part of a body moves in a circular path about an axis of rotation

Question 2

What is the axis of rotation called in a joint?

Answer 2

Fulcrum

Question 3

What are the 3 things you can say to describe angular motion?

Answer 3

Whether it’s whole/part of a body
Whether it’s a whole circle/part of a circle
The axis of rotation (normally a joint)

Question 4

How is angular motion created?

Answer 4

When a forces line of application passes outside the centre of mass of a body’s mass. This is termed an eccentric force/torque

Question 5

What is the definition of torque?

Answer 5

A turning or rotational force

Question 6

What is the resultant motion made from an eccentric force?

Answer 6

Angular motion/spin

Question 7

Definition of longitudinal axis of rotation?

Answer 7

Runs vertically through the centre of mass of a body from the top to bottom (head to toes)

Question 8

Definition of transverse axis of rotation?

Answer 8

Runs horizontally through the centre of mass of a body from side to side (left to right)`

Question 9

Definition of frontal axis of rotation?

Answer 9

Runs horizontally through the centre of mass of a body from front to back (through belly button)

Question 10

Example of longitudinal axis of rotation?

Answer 10

Dancer performing a pirouette

Question 11

Example of transverse axis of rotation?

Answer 11

Gymnast performing a front/back somersault

Question 12

Example of frontal axis of rotation?

Answer 12

Gymnast performing a cartwheel

Question 13

Definition of an axis of rotation?

Answer 13

An imaginary line that passes through the centre of mass about which the body/limb rotates

Question 14

What plane/axis of rotation does flexion/extension occur in?

Answer 14

Plane - sagittal

Axis of rotation - Transverse

Question 15

What plane/axis of rotation does abduction/adduction occur in?

Answer 15

Plane - Frontal

Axis of rotation - Frontal

Question 16

What plane/axis of rotation does rotation occur in?

Answer 16

Plane - Transverse

Axis of rotation - Longitudinal

Question 17

Definition of angular velocity?

Answer 17

Rate of change in angular displacement/rotation

Question 18

Calculation for angular velocity?

Answer 18

Angular displacement / Time

Question 19

Units of measurement for angular velocity?

Answer 19

Rad / s

Question 20

Definition for moment of inertia?

Answer 20

Resistance of a rotating body to change its state of angular motion

Question 21

Calculation for moment of inertia

Answer 21

MI = Sum of mass X r squared

r squared = distribution of mass from the axis of rotation squared

Question 22

Units of measurement for moment of inertia

Answer 22

kgm squared

Question 23

Definition of angular momentum

Answer 23

The quantity/amount of angular motion possessed by a rotating body

Question 24

Calculation for angular momentum

Answer 24

Moment of inertia X Angular velocity

Question 25

Units of measurement for angular momentum

Answer 25

kgm squared rad/s

Question 26

Definition of radian

Answer 26

A measure of the angle through which a body rotates | Degrees/180 X pi

Question 27

What are the 2 factors that affect the moment of inertia?

Answer 27

Mass of the body | Weight in relation to your axis of rotation

Question 28

How does a mass of a body affect the moment of inertia?

Answer 28

The larger the mass of a body the greater the MI (can't change during performance)

Question 29

Why do athletes doing sports requiring high levels of rotation normally have a lower mass?

Answer 29

Decreases moment of inertia (the resistance of a body to start rotating) so increases angular rotation

Question 30

How does the weight in relation to your axis of rotation affect the moment of inertia?

Answer 30

The further away the mass from the axis of rotation, the greater the moment of inertia so lower angular velocity. Can be changed during performance and therefore, more significant during performance.

Question 31

What is the parabolic curve for a diver?

Answer 31

Flight path of the centre of mass (can't be changed during flight)

Question 32

When is angular motion generated?

Answer 32

When the centre of mass passes outside the base of support. A force is applied outside the centre of mass, termed an eccentric force creates angular momentum.

Question 33

What is the analogue that goes with angular momentum relating it to N1?

Answer 33

A rotating body will continue to rotate around it's axis of rotation with constant angular momentum unless acted upon by an eccentric force.

Question 34

What is the analogue that goes with angular momentum relating it to N2?

Answer 34

The rate of change in angular momentum of a body is directly proportional to the size of the eccentric force and occurs in the same direction as the eccentric force is applied

Question 35

What is always constant angular velocity, moment of inertia or angular momentum?

Answer 35

Angular momentum