Angular motion

Question 1

Angular motion

Answer 1

Movement around a fixed point

Question 2

Examples of angular motion

Answer 2

• Somersault (body)
• Throwing a discuss (arm)

Question 3

Torque (moment)

Answer 3

• The rotational consequence of a force
• Turning force

Question 4

What happens to the torque of you increase the size of the force

Answer 4

Increases torque

Question 5

What happens to the torque if the same force is applied further away from the axis of rotation

Answer 5

Increases torque

Question 6

How to calculate the moment if force or torque

Answer 6

Moment of force or torque (N/M) =
Force (N) x Perpendicular distance from fulcrum (M)

Question 7

Newton’s first law to angular motion

Answer 7

A rotating body will continue to tur about its axis of rotation with constant angular momentum unless an external rotational force (torque) is exerted upon it

Question 8

Sporting example of Newton’s first law to angular motion

Answer 8

Ice skater spinning in the air. They will continue to spin until they land on the ice when an external force is exerted from the ice on the skates

Question 9

Newton’s second law to angular motion

Answer 9

The rate of change of angular momentum of a body is proportional to the force causing it and the change that takes place in the direction which the force acts

Question 10

Sporting example of Newton’s second law to angular motion

Answer 10

Ice skater
The greater the torque exerted, the faster the rotation will be

Question 11

Newton’s third law to angular motion

Answer 11

When a force is applied by one body to another, the second body will exert an equal and opposite force on the other body

Question 12

Sporting example of Newton’s third law to angular motion

Answer 12

Goalkeeper tips ball over the bar, they throw their arms up which causes the lower part of their legs to go back (reaction force)

Question 13

Angular displacement

Answer 13

The smallest change in angle between the start and finish point of rotation

Question 14

How is angular displacement measured

Answer 14

Is measured in degrees and radians

Question 15

How many degrees is 1 radian

Answer 15

57.3 degrees

Question 16

Radians

Answer 16

The unit of measurement for angles

Question 17

Angular velocity

Answer 17

The rate of change of angular displacement

Question 18

How to measure angular velocity

Answer 18

Angular velocity (rad/s) = Angular displacement (rad) / Time taken (s)

Question 19

Angular acceleration

Answer 19

The rate of change of angular velocity

Question 20

How to measure angular acceleration

Answer 20

Angular acceleration (rad/s2) = Chng in angular velocity (rad/s) / Time taken (s)

Question 21

Moment of inertia

Answer 21

Resistance of a body to angular motion

Question 22

What 2 things does moment of inertia depend on

Answer 22

1) Mass of the body
2) Distribution of mass around the axis

Question 23

Mass of the body/object influence on the moment of inertia

Answer 23

The greater the mass, the greater the resistance to change and therefore the greater moment of inertia

Question 24

Distribution of mass from the axis of rotation influence on the moment of inertia

Answer 24

The closer the mass is to the axis of rotation, the easier it is to turn, because the moment of inertia is low.

Question 25

Apply the distribution of mass from the axis of rotation influence on the moment of inertia for a diver performing a somersault

Answer 25

Open somersault has a higher moment of inertia than a tucked somersault because n the straight leg position, the distribution of the divers mass is further away from the axis of rotation

Question 26

Angular momentum

Answer 26

The quantity of rotation a body possesses

Question 27

How to calculate angular momentum

Answer 27

Angular momentum =
Moment of inertia x Angular velocity

Question 28

Apply the conservation of angular momentum to a figure skater at the start of theri spin

Answer 28

Arms/legs stretched out
|
Increase distance from axis of rotation
|
Large moment of inertia
|
Large angular momentum
|
Slow rotation (spin slower)

Question 29

Apply the conservation of angular momentum to a figure skater wen they increase angular velocity during the spin

Answer 29

Arms/legs brought in
|
Decrease distance from axis of rotation
|
Smaller moment of inertia
|
Smaller angular momentum
|
Fast rotation (spin quicker)