Conservation of Angular Momentum

Question 1

What is Angular Motion?

Answer 1

Movement of body part/pbject around an axis of rotation

Axis of rotation can be real or imaginary

Question 2

What is Angular distance?

Answer 2

How far something has travelled aorund an axis (measured in degrees)

Question 3

What is angular displacement?

Answer 3

Difference between initial and final angular position of object (degrees)

Question 4

What is Angular speed?

Answer 4

The angular distance travelled by time taken (degrees per second)

Question 5

What is Angular velocity

Important!

Answer 5

The rate of change of angular displacement over time (degrees per second)

Question 6

What is Angular Momentum

Answer 6

The amount of angular motion possessed by a body

Question 7

What is formula for Angular Momentum?

Answer 7

Angular Momentum = Moment of Inertia x Angular velocity

Question 8

What is Moment of Inertia?

Answer 8

A measure of an object’s resistance to change in its rate of rotation

Question 9

How is Moment of Inertia calculated?

Answer 9

MOI = Mass x Radius^2

Question 10

What happens to angular momentum when an object is in flight?

Answer 10

Angular momentum is conserved when the body is in flight

Question 11

Describe the relationship between Moment of Inertia and Angular velocity

Answer 11

Inversely proportional relationship

If one goes up, other goes down

Question 12

How can Moment of Inertia be increased?

Answer 12

Bringing mass of body/object away from axis of rotation (increase radius)

Question 13

How can Moment of Inertia be decreased?

Answer 13

Bringing mass of body/object closer from axis of rotation (decrease radius)

Question 14

Bringing mass of body closer to axis of rotation leads to what?

Answer 14

1. Smaller radius
2. Thus, less Moment of Inertia
3. Thus, increased angular velocity

Question 15

Bringing mass of body away from axis of rotation leads to what?

Answer 15

1. Larger radius
2. Thus, higher Moment of Inertia
3. Thus, decreased angular velocity

Question 16

How would your general answer for a Conservation of Angular Momentum question look like?

Answer 16

• Define angular momentum and state it is conserved when in flight
• Give formula for Angular Momentum
• Give formula for Moment of Inertia
• State the inversely proportional relationship between MOI and angular velocity
• Describe which on is decreasing and hence which one is increasing
• Describe how this is benefit with link back

Question 17

Why would a gymnist tuck in their knees to perform flips?

Answer 17

• Brings mass closer to axis of rotation
• Thus decreases radius
• Thus decreases moment of inertia
• Thus, angular velocity increases
• Hence, can do more flips in a given time for higher score

Question 18

Describe why a diver would extend body when entering water

Answer 18

• Bring mass away from axis of rotation
• Thus increase radius
• Increase Moment of Inertia
• Thus, decrease angular velocity
• Hence, can enter water safely, in correct position, and make less of a splash for more points

Question 19

Why is swimming/kicking with bent limbs beneficial?

Answer 19

• Mass closer to axis of rotation
• Thus, smaller radius,
• Thus, smaller Moment of Inertia
• Thus, greater angular velocity
• Thus, faster rotations for swimming, or faster kick