sound (topic 6)

Question 1

the accepted value for the speed of sound in air is 340 m/s, describe one way the student could improve the accuracy of their results without changing the equipment used (2)

Answer 1

• increase the range of distances measured
• repeat experiment several times and calculate average time

Question 2

explain why the student used data logging equipment instead of a handheld stopwatch (2)

Answer 2

• the times recorded are very small
• human reaction time would be a signifiant proportion of the final measurement
• stopwatch would result in inaccurate time measurements due to human reaction time

Question 3

state one use of ultrasound

Answer 3

• sonar
• echo location
• dog whistle

Question 4

state one use of infrasound

Answer 4

• studying the earths structure
• detecting seismic activity
• detecting meteorites

Question 5

describe how the vibrating fork causes a sound wave to travel through the air (2)

Answer 5

• air vibrates
• in the same direction as wave travel

Question 6

state the frequency range of human hearing

Answer 6

20 Hz - 20 kHz (20,000)

Question 7

describe a similarity and a difference between sound waves and visible light (2)

Answer 7

• both transfer energy from one point to another
• sound waves are longitudinal and light is transverse

Question 8

describe how ultrasound is used to determine the depth of the sea (4)

Answer 8

• ultrasound is emitted from the boat and travels towards the sea bed
• ultrasound reflects off the sea bed and is detected by the boat
• the time between emission and detection is recorded
• distance travelled by ultrasound = speed x time
• depth = distance travelled by ultrasound ÷ 2

Question 9

the speed of ultrasound in water is 1.5 km/s, calculate the current depth of water under the boat, 26ms

Answer 9