Angular Motion

Question 1

Define moment of inertia

Answer 1

The spread of mass from the axis of rotation

Question 2

Define angular velocity

Answer 2

Speed of rotation

Question 3

If a performer increases moment of inertia, what happens to angular velocity?

Answer 3

Decreases

Question 4

How can an increase in moment of inertia be achieved?

Answer 4

Spreading limbs away from the body

Question 5

If a performer decreases moment of inertia, what happens to angular velocity?

Answer 5

Increases

Question 6

How can a decrease in moment of inertia be achieved?

Answer 6

Bringing limbs towards the body and the axis of rotation

Question 7

How can angular momentum be calculated?

Answer 7

Moment of inertia x Angular velocity

Question 8

What is angular momentum?

Answer 8

Angular momentum relates to how much an object is rotating.

Angular momentum can be calculated using the formula: Angular momentum = moment of inertia x angular velocity.

Question 9

What happens to angular velocity when the moment of inertia increases?

Answer 9

Angular velocity decreases because the body is increasing its resistance to motion.

This is often observed when a performer straightens their body position or moves mass away from the axis of rotation.

Question 10

Define moment of inertia.

Answer 10

Moment of inertia is a value that describes the distribution of the mass of the object.

A low moment of inertia allows for a high angular velocity.

Question 11

How is angular momentum conserved?

Answer 11

An object has a constant angular momentum when it is neither speeding up nor slowing down.

This principle is critical in understanding rotational dynamics.

Question 12

Fill in the blank: Angular momentum = _______ x angular velocity.

Answer 12

moment of inertia

Question 13

What effect does tucking the body have on moment of inertia?

Answer 13

Moment of inertia is low when the performer is tucked.

This means that the mass is close to the axis of rotation, allowing for a higher angular velocity.

Question 14

What occurs to moment of inertia when a performer straightens their body?

Answer 14

Moment of inertia increases.

This is due to the mass moving away from the axis of rotation.

Question 15

Explain the relationship between moment of inertia, angular velocity, and angular momentum.

Answer 15

Angular momentum is the product of moment of inertia and angular velocity, indicating that as moment of inertia increases, angular velocity must decrease to maintain constant angular momentum.

This relationship highlights the balance between mass distribution and rotational speed.

Question 16

What happens to the moment of inertia when a performer straightens their body into a piked position during a dive?

Answer 16

The moment of inertia increases as the mass moves away from the axis of rotation.

Question 17

What effect does the increase in moment of inertia have on angular velocity during a dive?

Answer 17

Angular velocity decreases because the body is increasing its resistance to motion.

Question 18

When a performer is in a tucked position during a dive, where is their mass relative to the axis of rotation?

Answer 18

The mass is close to the axis of rotation.

Question 19

Fill in the blank: When a diver straightens their body, the _______ increases.

Answer 19

[moment of inertia]

Question 20

True or False: A tucked position during a dive leads to a lower moment of inertia.

Answer 20

True

Question 21

What is the relationship between mass distribution and angular velocity in diving?

Answer 21

As mass moves away from the axis of rotation, angular velocity decreases.

Question 22

What is angular momentum?

Answer 22

Angular momentum refers to the quantity of rotation

It is a product of moment of inertia and angular velocity.

Question 23

What is the formula for angular momentum?

Answer 23

Angular momentum = moment of inertia x angular velocity

This formula indicates how mass distribution and rotation speed are related.

Question 24

Define moment of inertia in the context of rotation.

Answer 24

Moment of inertia is resistance to spin

It describes how mass is distributed around the axis of rotation.

Question 25

How does an athlete change their moment of inertia?

Answer 25

By distributing their mass around the axis of rotation ## Footnote This can be done by extending or tucking their limbs.

Question 26

What happens to angular velocity when moment of inertia increases?

Answer 26

Angular velocity decreases ## Footnote This is due to the conservation of angular momentum.

Question 27

What occurs when an athlete tucks their arms and legs during rotation?

Answer 27

Moment of inertia decreases, leading to increased angular velocity ## Footnote This action allows for faster rotation.

Question 28

True or False: Angular momentum can change during an athlete's performance.

Answer 28

False ## Footnote Angular momentum remains constant as long as no external torque acts on the system.

Question 29

Fill in the blank: The athlete can decrease their speed of rotation by _______.

Answer 29

taking their arms and legs further away from the axis of rotation ## Footnote This increases their moment of inertia.

Question 30

What is the relationship between moment of inertia and angular velocity?

Answer 30

They are inversely related ## Footnote An increase in moment of inertia results in a decrease in angular velocity, and vice versa.

Question 31

How does changing body shape affect an athlete's rotation speed?

Answer 31

Altering body shape can modify moment of inertia, impacting angular velocity ## Footnote This is crucial for performance in sports requiring rotation.

Question 32

What is topspin?

Answer 32

Topspin is created by applying a force above the centre of mass, causing forward rotation of the object (tennis ball) ## Footnote For example, in tennis, this is achieved by hitting a groundstroke from low to high and 'brushing' over the top of the ball.