Unit 6 - Oscillations and Mechanical Waves

Question 1

Example of simple harmonic motion

Answer 1

Masses on springs and pendulum systems

Question 2

What is the one major things that systems in simple harmonic motion have

Answer 2

Resotring force

Question 3

What is a restoring force

Answer 3

A force that wants to return the system to eqbm (opposing what you want to do to it)

Question 4

In a simple harmonic oscilator the resotring force is proportional to

Answer 4

Proportional to the ammount of displacment in the system

Question 5

What is the equation connecting the force exerted by a spring, the spring constant and displacement

Answer 5

Fs = -kx

Question 6

Force is proportional to …. but not ….

Answer 6

Acceleration but not velocity

Question 7

Max displacement AKA

Answer 7

Displacement

Question 8

Period (T) is

Answer 8

The time taken for an entire cycle to occur

Question 9

Cos starts at

Answer 9

MAX amplitude (1)

Question 10

Sin starts at

Answer 10

Minimunim amplitude (0)

Question 11

x(t) = (2)

Answer 11

A cos (wt) or A sin (wt)

Question 12

What is w

Answer 12

2pi / T

Question 13

x(t) = (in terms of time period)

Answer 13

A cos ((2pi/T) t)

OR

A sin ((2pi/T) t)

Question 14

What is the effect of a change in amplitude on the peirod in a spring system

Answer 14

There is no effect

Question 15

T (for a spring)

Answer 15

2pi X root of (m/K)

m = mass
k = spring constant

Question 16

90 deg –> RAD

Answer 16

pi/2 rad

Question 17

2 pi rad –> DEG

Answer 17

360 deg

Question 18

What is the effect of adding a phase constant inside of the sine term

Answer 18

Shift the graph to the left in the negative x direction

Question 19

What is the effect of subtracting a phase constant inside of the sine term

Answer 19

Shifts the graph to the right

Question 20

What is the effect of changing the mass on a pendulum in terms of a pendulum

Answer 20

No effect on time period

Question 21

T (for a pendulum)

Answer 21

2pi x root (L/g)

L = length 
g = gravitational acceleration

Question 22

Define a mechanical wave

Answer 22

Distrubance through space which usually transfers energy

Question 23

What is a longitudinal wave

Answer 23

Waves where the direction of disturbance is in the same direction as the wave is travelling

Question 24

What is a tranverse wave

Answer 24

A wave where direction of energy transfer is perpendicular to the direction of energy transfer

Question 25

What is a wave pulse

Answer 25

Single period of a wave

Question 26

What is amplitude

Answer 26

From the resting point to the peak of the wave

Question 27

What is the period of a wave

Answer 27

TIme taken for a complete wave cycle to occur

Question 28

What is frequency

Answer 28

The number of cycles that occur per second

Question 29

Equation for frequency

Answer 29

f = 1/T

Question 30

Wavelength is

Answer 30

the distance travelled after one period

Question 31

Velocity -

Answer 31

Wavelenght/period Wavelength X frequency

Question 32

Sound travles as

Answer 32

A wave

Question 33

What is the only way to alter the speed of sound

Answer 33

Change tge prperties of the medium that it is travelling through

Question 34

What is the equation for the velocity of a sound wave through a given medium

Answer 34

V = ROOT (B/P)

Question 35

What is B

Answer 35

Bulk moduls

Question 36

An increased __________ almost always overides an_____________

Answer 36

Bulk moduulus //// Increase in density

Question 37

What type of air does sound travel faster through - why?

Answer 37

Faster through hotter air since hotter air is less dense

Question 38

Facts about ultrasound

Answer 38

20000 Hz Reflected when it reaches a change in medium Reflection detected by a transducer which calcuates time between initiation and return Distance is calculated to produce a 3D image

Question 39

How can you produce a CLEAER image from ultrasound

Answer 39

Higher freq and shorter wavelength so there is less diffraction

Question 40

What is the Doppler ffect

Answer 40

The apparent change in the freuqency of a wave based on relative motioon between the source of the wave and the observer

Question 41

What happens if the source of the wave is travelling at the same speed as the observer

Answer 41

Sonic boom - all waves arise at once

Question 42

What be observed if you move towards the source

Answer 42

Higher freq since more wave crests reach per second

Question 43

What would be observed if you move away from the source

Answer 43

Lower freqeuncy since fewer wave crests reach per second

Question 44

Fobs =

Answer 44

Fs . ((Vw+Vobs)/Vw)

Question 45

Where does wave interference occur

Answer 45

Where waves overlap in the same region

Question 46

Superposition says that

Answer 46

You can find he total wave by addiing together the contributing waves

Question 47

Constructvie interference

Answer 47

Forms a much bigger wave | When two waves are in phase or are spaced a distance apart that is an integer number of the wave lengths

Question 48

Destructive interfence

Answer 48

Forms a much smaller wave | When two waves are out of phase or a spaced at a distance which is not an integer multiple of the wavelengths

Question 49

In standing waves ANTINODES are NODES are

Answer 49

Antinodes points with most motion Nodes points with least motion

Question 50

In standing waves wavlength =

Answer 50

2L/N ``` L = length N = nodes ```

Question 51

What is the equation for wavelngth in a tube where one end is open

Answer 51

4L/N

Question 52

Beat frequency is where

Answer 52

Waves have different frequencies

Question 53

What is the equation of Beat freuqnecy

Answer 53

FB = modulus of F1-F2