Angular Motion

Question 1

What is angular motion?

Answer 1

Rotation. It involves movement around a fixed point or axis. E.g somersault

Question 2

When does angular motion occur?

Answer 2

When a force is applied outside of the centre of mass. An off centre f9rce is refered to as an eccentric force

Question 3

What is the transverse axis?

Answer 3

Runs side to side of the body. E.g a somersault

Question 4

What is the saggital axis?

Answer 4

Runs back to front. E.g cartwheel

Question 5

What is the longitudinal axis?

Answer 5

Runs top to bottom. E.g a spin in ice skating

Question 6

What is torque?

Answer 6

A turning force that causes an object to turn a out its axis of rotation.

Question 7

How cab torque be increased

Answer 7

Increase the size of the force
Apply the same force further form the COM.

Question 8

What is the calculation of moment of force?

Answer 8

Force x perpendicular distance from the fulcrum (metres)

Question 9

What is angular displacement?

Answer 9

The smallest change in angle between the starting and finishing point. This is measured in degrees and radians.

Question 10

What is a radian?

Answer 10

1 radian = 57.3 degrees

Question 11

What is angular velocity?

Answer 11

The rotational speed of an object and the axis about which the object is rotating. This is a vector due to the reference of direction. It is the rate of change of angular displacement

Question 12

How do you calculate angular velocity (rad/s)

Answer 12

Angular displacement (rad) ÷ time taken (s)

Question 13

What is angular acceleration?

Answer 13

The rate of change of angular velocity.
Angular acceleration (rad/s²) = change in angular velocity ÷ time taken (s)

Question 14

What is the moment of inertia?

Answer 14

Resistance if the body to angular motion

Question 15

What does the moment of inertia depend on

Answer 15

Mass
Distribution of mass

Question 16

How does the mass affect moment of inertia?

Answer 16

Greater mass means greater resistance to change and therefore greater moment of inertia

Question 17

How does the distribution of mass affect moment of inertia?

Answer 17

If its closer to the axis of rotation then its easier to turn because moment of inertia is low.

Question 18

What is angular momentum?

Answer 18

The quantity of rotation a body possesses. This depends on angular velocity and moment of inertia. These 2 are inversely proportionally.

Question 19

How do you work out angular momentum?

Answer 19

Moment of inertia x angular velocity

Question 20

Explain how angular momentum is a conserved quantity

Answer 20

It remains constant unless an external torque force acts upon it. This means changing distribution of mass can change torque as most angular motion occurs in the air or on ice when there is little to no friction, so doesn’t affect angular momentum.

Question 21

What is angular momentum measured in?

Answer 21

Kgm²/s

Question 22

What is angular velocity measured in?

Answer 22

Rads/s

Question 23

What is moment of inertia measured in?

Answer 23

Kgm²

Question 24

How can you apply newton’s first law to angular motion?

Answer 24

“A rotating body will continue to turn about its axis of rotation with constant angular motion unless and external rotational force is exerted upon it”.
E.g an ice skater spinning in the air will spin until they land kn the ice where torque is exerted from the ice on their skates which changes their state of angular momentum

Question 25

How can you apply newton's second law to angular motion?

Answer 25

"The rate of change of angular momentum of an body is proportional to the force causing it and the change that takes place in the direction in which the force acts". More torque is more rotation

Question 26

How can newton's third law be applied to angular momentum?

Answer 26

"When a force is applied to a body the second body will exerted and equal and opposite force on the other body". E.g as a goalkeeper tips the ball over the bar, they throw their arms up which causes the lower part of their body to go back