A - Angular motion :)

Question 1

What is angular rotation?

Answer 1

Refers to rotation and involves movement around an axis
*Occurs when a force is applied outside the centre of mass = eccentric force

Question 2

What is a torque?

Answer 2

*The rotational consequence of a force
*Applying force further away from axis of rotation increases the torque

Question 3

How do you calculate torque?

Answer 3

Moment of force/torque (Nm) = force (N) x perpendicular distance from fulcrum (m)

Question 4

Describe Newtons first law of angular motion
e.g?

Answer 4

*Law of inertia
A rotating body will continue to turn about its axis of rotation with constant angular momentum unless an external rotational force (torque) is exerted upon it
e.g figure skater continues to spin until hit ice and the torque exerted from the ice changes their state of angular momentum

Question 5

Describe Newtons second law of angular motion
e.g?

Answer 5

*Law of acceleration
The rate of change of angular momentum of a body is proportional to the torque causing it and the change that takes place in the direction in which the torque acts
e.g diver leaning forward from a board creates more angular momentum than standing straight

Question 6

Describe Newtons third law of angular motion

Answer 6

*Law of action/reaction
When a force (torque) is applied by one body to another, the second body will exert an equal and opposite force (torque) on the other body
e.g long jumper brings legs upwards causing a reaction

Question 7

Define angular displacement

Answer 7

The smallest change in angle between the start and finish point of a rotation
(radians)

Question 8

Define angular velocity

Answer 8

The rotational speed to the rotational speed of an object and the axis about which the object is rotating
The rate of change of angular displacement
(radians)

Question 9

How is angular velocity calculated?

Answer 9

Angular velocity (rad/s) = angular displacement (rad)
/
time (s)

Question 10

Define angular acceleration

Answer 10

The rate of change of angular velocity

Question 11

How is angular acceleration calculated?

Answer 11

Angular acceleration (rad/s2) = change in angular velocity (rad/s)
/
time (s)

Question 12

Define moment of inertia

Answer 12

The resistance to change in motion so moment of inertia is the resistance of a body to angular motion
Depends on mass and distribution of mass around axis of rotation

Question 13

How does mass affect moment of inertia?

Answer 13

Greater mass = greater resistance to change = greater moment of inertia

Question 14

How does distribution of mass from the axis of rotation affect moment of inertia?

Answer 14

Mass distributed further = greater moment of inertia

Question 15

Describe how a tucked somersault affects the moment of inertia

Answer 15

*Smaller moment of inertia
*Distribution of body mass is closer to axis of rotation
*Rotate quicker (quicker angular velocity)

Question 16

Describe how a straight somersault affects the moment of inertia

Answer 16

*Larger moment of inertia
*Distribution of body mass is further away from axis of rotation
*Rotate slower (slower angular velocity)

Question 17

Define angular momentum

Answer 17

The quantity of rotation a body possesses or spin

Question 18

How is angular momentum calculated?

Answer 18

Angular momentum = moment of inertia x angular velocity

Question 19

Describe the conservation of angular momentum
e.g?

Answer 19

*Stays constant in fight unless an external torque acts upon it
*Moment of inertia and angular velocity are inversly proportional
*AM cannot be changed during flight
*Need to create as much torque as possible in preparation
e.g ice skater (ice = friction free), arms in spin = smaller moment of inertia, increases angular velocity
arms out at end of spin = larger moment of inertia, decreases angular velocity