(Pi) Chapter 9: Periodic Motion, Waves And Sound

Front 1

What is conductivity theory?

Back 1

This theory states that a material's ability to conduct electricity depends on the number of electrolytes that are present in the material. This means that the number of charged particle present in a material will directly influence a materials ability to conduct electricty.

Front 2

Simple Harmonic Motion

Back 2

In this type of motion, a restorative force acts on an object constantly bring that object back to its equilibrium position. The magnitude of the force acting on the object will be directly proportional the displacement of the object.

Front 3

What are two systems that exhibit simple harmonic motion

Back 3

Springs and pendulums

Front 4

The force in a system that displays simple harmonic motion acts in what way

Back 4

The force in simple harmonic motion is directly proportional to displacement of the object.

Front 5

Hooke's Law

Back 5

This law is given by the equation F = -kx. This equation tells us that the force exerted by a spring on an object depends on the spring constant (k) multiplied by the displacement of the spring (x) from it equilibrium point

Front 6

What does the negative sign on the spring constant tell us?

Back 6

The negative sign tells when the spring is moved beyond the point of equilibrium, the force exerted by the spring will oppose the direction of the displace -- will be in the opposite direction of the displacement

Front 7

Definition of frequency

Back 7

The definition of frequency is the rate at which an object completes a cycle

Front 8

Unit for frequency

Back 8

Hertz (Hz)

Front 9

Definition of angular frequency

Back 9

Angular frequency is the rate at which an object completes a path of a certain arc of a circle

Front 10

Angular frequency of an object moving by way of a spring

Back 10

Angular frequency of an object is given by the equation √(k)/(m).

Front 11

If one spring is stretched out to a greater extent than another, what will be the difference in terms of velocity and acceleration.

Back 11

The velocity and acceleration will be greater with the spring that was stretched out to a greater extent. However, the FREQUENCY will be same for both springs. The only factors that will affect frequency of spring is the spring constant (k) and the mass (m) attached to spring.

Front 12

Potential Energy and Kinetic Energy of a spring

Back 12

A spring has a potential energy that is given by U = (1/2)kx^2 where (x) is the displacement and (k) is the spring constant. For a conservative system, the total potential energy and kinetic energy will be conserved an equal a constant.

Front 13

What are the two factors that will affect the angular frequency of mass on a spring?

Back 13

The value of the spring constant and the mass of the object.

Front 14

Force on a object being swung on a pendulum.

Back 14

The force is given by F = - mg sin (x). Sin (x) is the angle between the vertical line of the point of attachment downward and the arm of the pendulum. Again, the sin is negative to show the the force is in opposition to the displacement.

Front 15

Angular Frequency of object attached to pendulum.

Back 15

When an object is swung from a pendulum, the angular frequency is given by √(g)/(L). This means that only gravity (g) and the length of the arm (L) can affect the angular frequency.

Front 16

What are the two factors that can affect the angular frequency of an object on a pendulum

Back 16

The only two factors that can affect the angular frequency of an object on a pendulum are the gravity and the length of the pendulum arm.

Front 17

Potential Energy of a Pendulum

Back 17

The potential energy of the pendulum is given my U = mgh. A pendulum can also be seen as a conservative system which means that the potential energy and the kinetic energy will be conserved and equal to a constant.

Front 18

Transverse waves

Back 18

A transverse wave is a wave whereby a particle sitting on the crest of the wave will not move in the direction of the wave motion. This means that the motion of a wave will not move a particle in a transverse wave.

Front 19

Longitudinal Wave

Back 19

In a longitudinal wave, a particle sitting on the crest of the wave will move in a perpendicular motion to the direction of the wave. In other words, the wave will push particle in the direction that the wave is traveling in.

Front 20

What is the product of frequency and wavelength?

Back 20

Velocity = (frequency) x (wavelength). This means that if you have the frequency and wavelength of a wave, you can find the velocity of the wave.

Front 21

If velocity is kept constant, how is the relationship between frequency and wavelength?

Back 21

Frequency and wavelength are inverses of each other if the velocity is constant. This means that as the wave length goes up the velocity goes down.

Front 22

Relationship between period and frequency

Back 22

F = 1/T

Front 23

Phase difference

Back 23

The extent to which one wave is out of phase with another. One wave might have a crest that is higher than another or below that crest of another

Front 24

Principle of Superposition

Back 24

This principle states that if you have two wave that are in phase, they combine in such a way that the amplitudes will combine. However, if the waves are out of phase, then the amplitude will be the difference of the amplitudes of the waves. One way to think about this is the positive and negative. If the waves are the same sign, they add. If the waves are of difference signs, they subtract.

Front 25

Incident wave vs reflected wave

Back 25

When a wave travels down a medium to a fixed point, at that fixed point the wave will be reflected and inverted. The initial wave is called the incident wave and the new wave is called the reflected wave.

Front 26

Nodes

Back 26

Points in a wave where this is no energy or movement

Front 27

Anti Nodes

Back 27

Points in a wave where there is maximum energy and maximum amplitude

Front 28

Natural Frequency

Back 28

The frequency at which an object will vibrate when the object is disturbed

Front 29

How are the vibrations of an object that creates a rich tone related to each other?

Back 29

These object are vibrating at frequencies that are whole number ratios of each other.

Front 30

What is happening to object that is resonating?

Back 30

The natural frequency of the object is equivalent to forced frequency of the object.

Front 31

What kind of wave is a sound wave?

Back 31

Longitudinal wave

Front 32

Can sound travel through a vacuum

Back 32

No

Front 33

Speed at which sound travels

Back 33

The speed at which sound travels is square root of the density of the material through which the sound is traveling

Front 34

Speed of sound in air

Back 34

331 m/s

Front 35

Audible Waves

Back 35

Waves that human beings can pick up are within the 20-20,000 Hz range. Infrasonic waves are below that range while ultrasonic is above that range

Front 36

Particle density and the movement of sound waves

Back 36

As the sound waves move through a medium, the medium experiences regions of compression and decompression due to energy of the sound wave

Front 37

Intensity of the sound wave

Back 37

The intensity of the sound wave can be measured by I = P/A: Intensity = Pressure / Area

Front 38

How is sound produced?

Back 38

Sound is produced through the mechanical disturbances of particles in a medium

Front 39

Notes on Logs

Back 39

If you have a log to a certain power, then you can take that power and just pull it in front of that log

Front 40

Pitch

Back 40

Our perception of the frequency of sound

Front 41

Beat

Back 41

When there are two wave in the audible region that add constructively or destructively then the change in the amplitude will be perceived as a beat.

Front 42

Doppler effect

Back 42

If a source of sound is moving toward you then you will perceive the sound as having a higher frequency and if it is moving away from you you will perceive it as having a lower frequency