P12 - Sound

Question 1

speed of sound and temp

Answer 1

varies with temp

Question 2

speed of sound

Answer 2

340 m/s @ 15.c

Question 3

sound and a vacuum

Answer 3

cannot travel through a vacuum

Question 4

compressions and rarefactions

Answer 4

as the object vibrates
-pulls/pushes repeatedly on air

Question 5

sound and ear

Answer 5

as the object vibrates
-pulls/pushes repeatedly on air
-wave reaches ear
-makes eardrums vibrate
-send signals to brain

Question 6

why is sound longitudinal

Answer 6

-air vibrates along direction of energy transfer

Question 7

how to investigate waves methods

Answer 7

-ripple tank for water waves
-stretched string for waves in a solid
-signal generator/loudspeaker for sound waves

Question 8

echo

Answer 8

reflection of sound that can be heard
-smooth hard surfaces (bare walls)

Question 9

time delay

Answer 9

time taken for sound to travel to wall + back

Question 10

speed of echo

Answer 10

-distance to wall and back/time delay

Question 11

why can sound not travel through a vacuum

Answer 11

no matter for vibrations to work on

Question 12

increasing loudness =

Answer 12

increasing amplitude (taller wave)

Question 13

pitch increases =

Answer 13

frequency increases

Question 14

hearing range for humans

Answer 14

20 Hz to 20KHz

Question 15

why do humans have a limited hearing range

Answer 15

-conversion of sound waves to vibrations only happens over a limited frequency range

Question 16

how do vibrations travel through a solid

Answer 16

-sound entering a solid is converted into vibration
-able to travel through

Question 17

speed of sound changes as

Answer 17

-mediums vary

Question 18

changes when sound moves from 1 medium to another

Answer 18

no change in frequency
-change in speed/wavelength

Question 19

echo sounding purposes

Answer 19

-pulses of high frequency sound waves are sent to detect object in deep water
-measures water depth below ship

Question 20

echo sounding works by

Answer 20

-pulses are reflected by object
- detected by receiver at same height as transmitter
-time is measured

Question 21

formula for depth of water by echo sounding

Answer 21

0.5 x speed x time

Question 22

ultrasound waves

Answer 22

above frequency humans can detect
-above 20kHz

Question 23

uses for ultrasound waves

Answer 23

-prenatal scans
-images of organs
-

Question 24

scanning with ultrasound method

Answer 24

-transducer placed on body surface and displays on screen

Question 25

transducer

Answer 25

produces and detects pulses /ultrasound waves

Question 26

how do ultrasounds work

Answer 26

-waves are partially reflected from diff tissue boundaries in its path
-waves are returned to transducer as a sequence of reflected waves arriving at diff times
-forms image on a screen

Question 27

pros of ultrasound use

Answer 27

used to scan organs/ soft tissues (unlike x rays)
-non ionising = harmless

Question 28

non ionising

Answer 28

not enough energy to remove an electron to ionise an atom

Question 29

Industrial imaging and ultrasounds purpose

Answer 29

-flaws in metal castings can be detected

Question 30

Industrial imaging and ultrasounds method

Answer 30

-transducer sends waves into block
-ultrasound waves are partly reflected + detected
-displayed on screen

Question 31

ultrasound formula for distance travelled by wave

Answer 31

speed of ultrasound waves x time taken