Angular motion

Question 1

What is rotation?

Answer 1

Movement around a fixed point/axis.

Question 2

what is angular motion?

Answer 2

Movement of a body or part of a body in a circular path about an axis of rotation.

Question 3

How is angular motion created?

Answer 3

An eccentric force, one applied outside the COM.

Question 4

What are the 3 axis of rotation?

Answer 4

1.) Transverse
2.) Sagittal
3.) Longitudinal

Question 5

What is torque?

Answer 5

The moment of force causing an object to turn about it’s axis of rotation.

Question 6

What 2 things is torque dependent on?

Answer 6

1.) The greater the size of the force the greater the torque.
2.) Application of the same force further away from the axis will increase torque.

Question 7

How can we calculate the Moment of force/torque (Nm)?

Answer 7

Moment of force / toque (Nm) = Force (N) X Perpendicular distance from the fulcrum (M)

Question 8

What 2 arms can torque have?

Answer 8

1.) Resistant
2.) Effort

Question 9

When is equilibrium achieved?

Answer 9

When the resistance arm is equal to the effort arm.

Question 10

What is the formula for angular momentum?

Answer 10

Angular momentum = Moment of inertia x angular velocity.

Question 11

What is the moment of inertia?

Answer 11

Moment of inertia is the resistance of a body to change it’s state of angular motion or rotation.

Question 12

What is Newton’s first law of angular motion?

Answer 12

Every body continues in its state of rest or will turn about its axis of rotation unless compelled to change that state by an external rotational force (torque) acting upon it.

Question 13

What factors affect Moment of inertia

Answer 13

-Mass
-Distribution of mass from axis

Question 14

What is the formula for Moment of inertia?

Answer 14

MI = Mass x Distribution of mass from axis

Question 15

When moment of inertia is …… Angular velocity is …..

Answer 15

-low
-high

visa versa.

Question 16

What is Newton’s second law of angular motion?

Answer 16

he rate of change of angular momentum (acceleration) of a body is proportional to the force (torque) causing it and the change that takes place in the direction which the force (torque) acts.

Question 17

What is Newton’s third law of angular motion?

Answer 17

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.”

Question 18

What is angular displacement (rad)?

Answer 18

This is the smallest change in angle between the starting and finishing point.

Question 19

1 Radian =

Answer 19

57.3 degrees.

Question 20

What is angular velocity (rad/s)?

Answer 20

The rotational speed of an object and the axis about which the object is rotating.

Question 21

What is the formula for angular velocity (rad/s)?

Answer 21

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

Question 22

What is angular acceleration (ras/s2)?

Answer 22

Angular acceleration is the rate of change of angular velocity.

Question 23

What is the formula for angular acceleration (rad/s2)?

Answer 23

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

Question 24

How does mass effect the Moment of inertia?

Answer 24

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

Question 25

How does the distribution of mass from the axis of rotation effect the Moment of inertia?

Answer 25

Closer the mass to the axis of rotation, the smaller the inertia. Thus, the easier it is to rotate.

Question 26

What is the formula for angular momentum?

Answer 26

Angular momentum =
angular velocity X moment of inertia

Question 27

Explain the conservation of angular momentum?

Answer 27

-If the mass moves closer to the axis of rotation (tuck) moment of inertia decreases & angular velocity increases BECAUSE angular momentum is conserved.

-If the mass moves away from the axis of rotation the moment of inertia increases & angular velocity decreases BECAUSE angular momentum is conserved.