Waves And Oscillation

Question 1

Define waves (3)

Answer 1

-an oscillation that propagates from one place to another
-they oscillate at well defined speeds determined by the property of the material
-they carry energy

Question 2

State 2 types of waves (2)

Answer 2

-Longitudinal
-transverse

Question 3

Define transverse waves (2)

Answer 3

-a wave in which particles oscillate perpendicular to the direction of the wave travel
-they show crest and troughs

Question 4

State examples of transverse waves (2)

Answer 4

-light
-electromagnetic waves

Question 5

Define longitudinal waves (2)

Answer 5

-a wave in which particles oscillate parallel to the direction of wave and energy transfer
-they show areas of compression and rarefaction

Question 6

What does compression mean (1)

Answer 6

-areas of increased pressure and density

Question 7

What does rarefaction mean (1)

Answer 7

-areas of decreased pressure

Question 8

State examples of longitudinal waves (2)

Answer 8

-sound waves
-ultrasound waves

Question 9

Why are longitudinal and transverse waves also called as harmonic waves (2)

Answer 9

-because they’re waves where the pattern of disturbance repeats regularly

Question 10

What are the key features of harmonic waves (3)

Answer 10

-equal spacing
-regular pattern
-well defined frequency

Question 11

How is energy transmitted through longitudinal waves (3)

Answer 11

-particles in the medium vibrate as they are given energy
-the compression causes the nearby particles to also vibrate with more energy
-this produces a compression further along the medium

Question 12

Define wavelength (2)

Answer 12

-distance over which a wave repeats
-length of one whole cycle

Question 13

Define frequency (1)

Answer 13

-number of vibration per unit time passing a given point

Question 14

Define period (1)

Answer 14

-the time taken for a whole cycle to complete

Question 15

Define amplitude (1)

Answer 15

-maximum displacement of a wave from its stationary point

Question 16

State the formula of frequency (2)

Answer 16

F = 1/ period

F = speed of wave / wavelength

Question 17

State the formula for speed of wave (1)

Answer 17

Speed of wave = distance / time

Question 18

What is the speed of sound in air under normal ATM and temperature (1)

Answer 18

V = 343m/s

Question 19

How is speed determined in solids (1)

Answer 19

-the stiffer the material, the faster the sound wave is

(Sometimes to calculate speed of sound you may have to use Kinematics equations)

Question 20

You drop a stone from rest into a well that is 7.35m deep. How long does it take before you hear a splash (3)

Answer 20

Distance = UT + 1/2at^2
7.35 = 0xt + 1/2x9.81xt2
T= 1.22

Distance = velocity x time
7.35/343
T = 0.0214s

T = T1 + T2
0.0214 + 1.22
=1.24s

Question 21

How is the pitch of sound determined (1)

Answer 21

By frequency

Question 22

What is the range of pitch humans can hear (1)

Answer 22

20Hz - 20,000Hz

Question 23

Define ultrasonic (1)

Answer 23

Sounds with the frequencies above the human hearing range

Question 24

Define infrasonic (1)

Answer 24

Sounds with frequencies below the human hearing range

Question 25

What are the medical application of ultrasonic (1)

Answer 25

-used to image a fetus in the womb by sending burst of ultrasound into the body and measuring the time delay of echos

Question 26

How is the loudness of sound determined and define it (2)

Answer 26

-By Intensity
-which is by the amount of energy that passes through a given area in a given time

Question 27

State the formula for intensity of sound (2)

Answer 27

Intensity = energy/ (area x time)

Intensity = power/area

Question 28

Why does the intensity of sound decreases as we move away from the sound
And state a formula for intensity with respect to distance (2)

Answer 28

-energy emerged per time by the source spreads out over a large area

Intensity with distance = power/ (4 x pie x distance^2)
SI unit = w/m^2

OR

Intensity2 = (distance1 / distance2)^2 x intensity1. [this formula is used when have to find another intensity]

Question 29

How is the speed of a wave determined (1)

Answer 29

-by the properties of the medium through which it propagates

Speed = distance/time

Question 30

What are the characteristics that determine the speed of a wave (2)

Answer 30

-tension in the string
-mass of the string

Question 31

Why is tension required to form a wave ? (2)

Answer 31

-it provides the restoring force necessary to establish and sustain a wave motion
-if the tension is increases the string becomes less slack so waves will travel though the string more rapidly

Question 32

How does mass affect the motion of wave (2)

Answer 32

-the heavier a rope or string, the slower the speed of wave on it
-because a heavy string responds slowly to a given disturbance due to its inertia

Question 33

State the equation of mass per length (1)

Answer 33

Mass per length = mass / length

Question 34

State the equation of speed of wave on a string (1)

Answer 34

Speed = square root ( force / mass per length )

Question 35

A rope of length L and mass M hangs from a ceiling. If the bottom of the rope is given a gentle wiggle, a wave will travel to the top of the rope. As the wave travels upwards does it’s speed increase, decrease or stay the same (4)

Answer 35

Increases
-because mass per length is same top to bottom
-tension is zero at the bottom and increases to MG ti the top
-tension increases with height so does speed

Question 36

Define periodic motion (1)

Answer 36

A motion that repeats itself over time