The City SchoolPrep Girls North Nazimabad

Science worksheet Class 8Topic: Sound and Hearing

Name __________________ Section________ Date___________

Q.1 Look at the diagrams of the musical instruments. The three diagrams show some ways of producing sounds.

(a) For each diagram name the part which is vibrating.(i) The vibrating part of a guitar is __________________ .(ii) The vibrating part of a drum is __________________ .(iii) The vibrating part of a recorder is _________________ .

(b) Most people can hear sounds of pitch ranging from ________ to 20,000 vibrations every second. (i) What is the name for sounds that have a pitch higher than 20,000 vibrations every second................?

Q.2 Look at the table below. It shows three keywords, their definitions and the units used for that keyword. They are not in order. Using straight lines, link the correct keyword with its definition and unit of measurement.

Q.3 Choose words from the list below to complete the following sentences. Higher, Lower, Louder, Quieter(i) A musical note with a high frequency sounds ________________ than a musical note played at a low frequency. (ii) A musical note with large amplitude sounds _____________ than a musical note with small amplitude. Q.4Nawaz has put an electric bell in an airtight glass jar.The bell and jar are

shown in the picture below. At first,Nawaz could hear the bell ringing. But when

his teacher pumped the air out of the jar, Nawaz could not hear the bell.

a) What is a vacuum?

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b) Why couldn’t Nawaz hear the bell when the air had been pumped out of the jar? __________________________________________________________________c) Explain why sound travels faster through water than through air. _________________________________________________________________________________________________________________________________________________________________________________________

Q.5(A)The diagram below shows an oscilloscope with a sound wave produced by a musical instrument Each square represents a distance of 1cm.(a) Use the above fact to state the wavelength and amplitude of the wave..................................................................................................................................................................................................................................................................... (i)(b) The diagram(ii) shows a new sound produced by the same musical instrument.State how this new sound compares to the one produced in question 1....................................................................................................................................................................................................................................................................(c) The diagram (iii) shows another new sound produced by the same musical instrument. (ii) State how this new sound compares to the one produced in the first diagram.....................................................................................................................................(d) On the first diagram draw what you would see on the oscilloscope if the musical instrument played a quieter note that has twice the pitch. (iii)

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(B) The diagram shows a guitar. (i) Describe how the guitar produces sounds................................................................................................................................................................................................................................................................................................(ii) Describe how the guitar can be made to produce louder sounds.....................................................................................................................................................

(iii) State two ways that the guitar can be made to produce higher pitch sounds...............................................................................................................................................................................................................................................................................................................................................

Q.6 A Company operates a quarry near local housing. People living near this quarry complained about the high noise levels. The company then built an earth barrier to reduce the noise levels that reached the houses. This is shown in the diagram below. (i) State what is meant by noise.______________________________________________________________________________

(ii) Why is it important to reduce noise?

........................................................................................................................................................................ (iii) Describe how the barrier reduced noise levels at the houses.____________________________________________________________________________________________

Q.7 Which diagram below shows the pattern that would be seen on the oscilloscope;A high pitch soft sound------------------------A low pith loud sound------------------------A low pitch soft sound-----------------------A high pitch loud sound-----------------------

Q.8Measure wavelength and amplitude of the following patterns in diagram B.

Q.9 (i) Which one is a high frequency wave and why?______________________________________________________________________________________________(ii)Define wave length._____________________________________________________________________________________________

Q.10Why do old people listen loud low pitch sound?________________________________________________________________________________________________Q.11 What is echo?________________________________________________________________________________________________Q.12Label the given human ear diagram.

13.A wave travels along a stretched spring. Fig. shows the appearance of the spring at one instant

(a) (i) On Fig. label one compression.(ii) Describe what is meant by a compression.

(iii) Sound waves also contain compressions and rarefactions. Give one other similarity between the motion of particles in a sound wave and the motion of coils in the stretched spring.(iv) Measure the wavelength of the wave.

2. (a) Fig. 2 shows the position of layers of air, at one moment, as a sound wave of constant frequency passes through the air. Compressions are labeled C. Rarefactions are labeled R.

(i)State how Fig. 2 would change if1. the sound had a higher frequency,2. the sound were louder.

(ii)On Fig 2., draw a line marked with arrows at each end to show the wavelength of the sound.

14. Fig. 3 shows a loudspeaker cone oscillating to produce sound wavesState the effect on the loudness and pitch of the sound from the loudspeaker when(i) the amplitude increases but the frequency of the sound stays the same,I. loudnessII. Pitch(ii) the amplitude stays the same but the frequency increases.I. loudnessII. Pitch15. A disused railway line has a length of 300 m. A man puts his ear against one end of therail and another man hits the other end with a metal hammer, as shown in Fig.

a) (i) State an approximate value for the speed of sound in air.(iii) Sound travels at 5000 m / s in steel. Calculate the time it takes for the sound to travel along the rail.(b) The man with his ear to the railway line actually hears two sounds from the hammer, separated by a short interval. Explain why he hears two sounds.

16. The interval between the lightning flash being seen and the thunder being heard is 3.6 s.The speed of sound in air is 340 m/s.(i) Calculate the distance between the thunderstorm and the observer.(ii) Explain why the speed of light is not taken into account in this calculation.

17.The diagram shows a ship using an Echo locator (SONAR) to find a shoal of fish. The pulsed wave is transmitted from the ship, which is then reflected off the top of the shoal and is then picked up by the receiver. (c) The time taken to receive the echo is 0.2s after transmission. Calculate how deep the ship has to lower its fishing nets to catch the top of the shoal.

18.A man claps his hands on a hilltop. He hears the echo 0.7 s later. (i) If the speed of sound is 340 m/s, how far away was the surface from which the sound rebounded?The strings on a guitar have a natural frequency of vibration. When plucked they vibrate and give out a note of that frequency. (a) What would a musician call the frequency of a note? ......................................................................................................................................................................... Shortening a string changes its frequency of vibration. (i) How do musicians shorten guitar strings? .........................................................................................................................................................................) How does the frequency of the note change when the string is shortened?(c) The string’s natural frequency can be changed by changing its tension. How is the tension of a guitar string changed?19.Explain why it is dangerous to listen to loud music for long periods of time.

20.Below is a diagram of a wave (a) Name the parts of the wave labelled A, B, C and D. A:

(b) (i) The frequency of a wave is the number of cycles it completes per second. What is the unit of frequency? ................................................................................................................

21A ship sends out a pulse of sound and receives an echo back one second later. If the water is 750 m deep, what is the speed of sound in water?

22.When her friend Hazel, strikes the spoon with a pencil, Katie hears a sound like a bell. Explain the reason for this.

1. Ship's captains can use sound to find out how deep the water is. This is calledA. ? water soundingB. ? echo soundingC. ? sound depthD. ? bottom sounding2. a loud sound has aA. ? small amplitudeB. ? large amplitudeC. ? high frequencyD. ? low frequency3. ultrasound isA. ? sounds too quiet for us to hearB. ? none of theseC. ? sounds too high-pitched for us to hearD. ? sounds too low-pitched for us to hear4. a wave with a short wavelength hasA. ? a large amplitudeB. ? a small amplitudeC. ? a low frequencyD. ? a high frequency5. the three small bones in your middle ear are calledA. ? hammer, anvil, stirrupB. ? hammer, anvil, horseshoeC. ? bridle, stirrup, hammerD. ? hammer, anvil, bridle6. a sound travels 1,000m in 3 seconds. The speed of sound isA. ? 33,000 m/sB. ? 3,300 m/sC. ? 3 m/sD. ? 330 m/s7. a tighter guitar string would vibrate atA. ? a higher frequencyB. ? an infrasonic frequencyC. ? a lower frequencyD. ? the same frequency as a slack string8. sound waves in air areA. ? longitudinalB. ? amplitudeC. ? transverseD. ? waveform9. having two ears rather than one is an advantage, becauseA. ? we can tell which direction sound is coming from by which ear is loudestB. ? we can hear quiet sounds more clearlyC. ? we can use time-of-arrival-difference to tell which direction sounds are coming fromD. ? we can hear higher-pitched sounds

10. frequency is measured inA. ? decibelsB. ? voltsC. ? secondsD. ? Hertz11. sound waves occur when particlesA. ? vibrateB. ? heat upC. ? expandD. ? move12. "frequency" meansA. ? how tall the waves areB. ? how many waves per minuteC. ? radio wavesD. ? how many waves per second13. a high-pitched sound has aA. ? large amplitudeB. ? high frequencyC. ? small amplitudeD. ? low frequency14. a wave with a long wavelength hasA. ? a large amplitudeB. ? a high frequencyC. ? a low frequencyD. ? a small amplitude15. which is the correct sequence?A. ? eardrum; auditory nerve; hammer, anvil & stirrup bones; auditory nerveB. ? eardrum; cochlea; hammer, anvil & stirrup bones; auditory nerveC. ? eardrum; hammer, anvil & stirrup bones; cochlea; auditory nerveD. ? auditory nerve; cochlea; hammer, anvil & stirrup bones; eardrum16. a microphone changesA. ? light energy into electrical energyB. ? sound energy into light energyC. ? electrical energy into sound energyD. ? sound energy into electrical energy17. sound travelsA. ? slightly slower than lightB. ? at the same speed as lightC. ? much slower than lightD. ? faster than light18. where does sound travel fastest?A. ? in gasesB. ? in solidsC. ? the speed is the same in solids, liquids and gasesD. ? in liquids19. Emily claps her hands, and hears the echo from a wall 2 seconds later. (Speed of sound = 330 m/s)A. ? the wall is 300 metres awayB. ? the wall is 165 metres awayC. ? the wall is 660 metres away

D. ? the wall is 330 metres away20. the speed of sound in air is aroundA. ? 1,500 m/sB. ? 550m/sC. ? 330 m/sD. ? 1,100 m/s21. ultrasound is used byA. ? batsB. ? catsC. ? whalesD. ? elephants22. which of these is true?A. ? sound cannot travel through a vacuumB. ? sound travels faster through gases than through solidsC. ? sound cannot travel through solidsD. ? sound can travel through a vacuum23. with a longitudinal waveA. ? the vibration has a low frequencyB. ? the vibration is in the same direction as the wave travelsC. ? the vibration is at right angles to the direction the wave travelsD. ? the vibration is small24. which of these is false?A. ? sound travels slower through gases than through solidsB. ? frequency is measured in HertzC. ? sound cannot travel without a mediumD. ? sound cannot travel through liquids25. a wave with a high frequency hasA. ? a short wavelengthB. ? a low pitchC. ? a small amplitudeD. ? a long wavelength26. The usual range of human hearing is fromA. ? 20Hz to 18KHzB. ? 30Hz to 25kHzC. ? 10Hz to 13kHzD. ? 50Hz to 25kHz27. where will you hear the most echoes?A. ? an empty sports hallB. ? a crowded sports hallC. ? a bare living roomD. ? a furnished living room28. normal conversation is aroundA. ? 110 decibelsB. ? 80 decibelsC. ? 90 decibelsD. ? 50 decibels29. loudness is measured inA. ? HertzB. ? volts

C. ? VUD. ? decibels30. we can see the shape of sound waves on aA. ? VU meterB. ? Decibel meterC. ? OscilloscopeD. ? Frequency Meter