Q2. Three Pupils Watched a Firework Display

KS3 8L Phx EQ 39marks

Q2. Three pupils watched a firework display.

(a) A man lit the fireworks. He wore ear defenders.

Why should he wear ear defenders when he is close to loud fireworks?

...... 1 mark

(b) A rocket exploded making a loud sound and a bright flash.Peter, Sabrina and Jan were standing at different distances from the rocket.

When the rocket exploded, Jan heard the quietest sound.Why did Jan hear the quietest sound?

...... 1 mark

What does this tell you about the speed of light and the speed of sound?

...... 1 mark

(d) Complete the sentences below using words from the list.

chemical electrical heat light sound

(i) Jan, Sabrina and Peter could see the rocket explode because it

gave out ...... energy.

1 mark

(ii) They could hear the rocket explode because it gave out

...... energy.

1 mark

(e) When the rocket stopped burning it fell to the ground.What force caused it to fall to the ground?

...... 1 mark

(c) Ultrasound is used for pre-natal scanning. This is much safer than using X-rays. However, doctors were only sure it was safe after experiments on mice.

Explain whether or not you think that these experiments were justified.

......

...... 2 marks

Q6. The diagram shows part of an ear.

Sound waves enter the ear and make the ear drum vibrate.

(a) The pitch of the sound is increased. What difference will this make to the way the ear drum vibrates?

...... 1 mark

(b) The sound is made louder. What difference will this make to the way the ear drumvibrates?

...... 1 mark

(a) An early type of echo sounder for a boat produces a sound of frequency 2000 Hz.

(i) The wavelength of this sound in water is 0.75 m. What is the speed of the sound in water? Give the unit.

...... 1 mark

(ii) This sound is heard by the operator as a brief ‘ping’. The speed of sound in air is 330 m/s. What is the wavelength of the sound in air? Give the unit.

...... 1 mark

(iii) Modern echo sounders use higher frequencies than the early type. Complete the sentence below to describe how the wavelength produced by a modern echo sounder compares with that produced by the early type.

The wavelength produced by a modern echo sounder is

...... 1 mark

(b) The diagram shows a wave in a ‘slinky’ spring.

The frequency of the waves is 5 pulses per second and the wavelength is 80 cm.

What is the wave speed? Give the unit.

...... 1 mark

Q8. Ultrasound waves are very high frequency sound waves. They cannot be heard by humans.

(a) Ultrasound waves can be used to clean jewellery.

The jewellery is put into a container of cleaning fluid.

Complete each sentence to explain how ultrasound can clean jewellery.

The ultrasound generator makes the molecules of the cleaning fluid

...... The molecules knock particles of ......

from the surface of the jewellery.

(2)

(b) Give a medical use for ultrasound.

...... 1 mark

The diagrams show three ultrasound waves.Each wave is represented on an identical CRO screen, A, B and C.

Screen A / Screen B / Screen C

(i) How many complete waves are shown on screen B? ......

(1)

(ii)Which screen shows the waves with the highest frequency?

Screen ......

(1)

Q9. (a) Explain what an ultrasound wave is.

......

...... 2 marks

(b) Ultrasound waves can be used to clean jewellery.

One method is to put the jewellery in a bath of cleaning fluid which contains an electronic oscillator. The electronic oscillator generates ultrasound waves in the cleaning fluid.

Suggest how these waves clean the jewellery.

......

...... 2 marks

Q10. (a) A student uses a microphone to send different sounds to an oscilloscope. The diagrams show five traces, A, B, C, D and E, on the oscilloscope. All the traces are drawn to the same scale.

(i) Which three diagrams show traces with the same amplitude?

Diagrams ...... , ...... and ......

(1)

(ii) Which two diagrams show traces with the same frequency?

Diagrams ...... and ...... (1)

(b) The diagram shows the sound frequencies which some living things can hear.

(i) What is the widest range of frequencies that a human child can hear?

...... 1 mark

(ii) Why can some dog whistles be heard by dogs but not by humans?

...... 1 mark

(c) An ultrasound scan can be used to make a picture of a baby in its mother’s womb. An ultrasound transmitter and detector are placed above the mother’s womb. Ultrasound goes into the body of the mother and into the body of the baby.

Use the correct words from the box to complete the sentences.

detectorreflectionrefractionsoundsubstancetransmitter

(i) When the ultrasound crosses from one ...... to another,

some ultrasound becomes an echo caused by ......

(ii) This information is collected by the ultrasound ......

and made into a picture on a screen.

(3)

Q11.Table 1 shows the hearing ranges for some different species of animal.

Table 1

Species of animal / Approximate hearing rangein Hz
Bat / 20–120 000
Cat / 45–64 000
Chicken / 125–2000
Porpoise / 75–150 000

(a) Use the data in Table 1 to answer the questions.

(i) Which species of animal can hear the highest frequency?

...... 1 mark

(ii)Which species of animal has the smallest frequency range?

...... 1 mark

(b) (i) What is the average hearing range for healthy young humans?

...... 1 mark

(ii)Human hearing is sensitive to a range of loudness. The units of loudness are decibels (dB).

Table 2 shows the loudness of some sounds.

Table 2

Sound / Loudness in dB
Busy road traffic / 70
Disco (at the front) / 110
Normal talking / 60
Personal stereo (loud) / 100
Vacuum cleaner / 80
Whisper / 20

Sounds up to 80 dB cause no damage to hearing, no matter how long you listen to the sound. They are described as ‘safe sounds’.

Which sounds in Table 2 are considered ‘safe’?

......

...... 2 mark

The maximum time that does not cause damage to hearing is shown in Table 3.

Table 3

Sound loudness in dB / Time limit for exposure
Up to 80 / No limit
85 / 8 hours
90 / 4 hours
95 / 2 hours
100 / 1 hour
105 / 30 minutes
110 / 15 minutes
115 / 7.5 minutes
120 / 3.75 minutes

(i) Describe the pattern shown in Table 3 for increasing loudness from 85 dB.

......

(2)

(ii)Use data from Table 2 and Table 3 to give the maximum time you should listen to a loud personal stereo each day.

...... 1 mark

Mark Scheme

M2. (a) any one from

• loud sounds can damage hearing

accept ‘they could damage his hearing’

• to protect his ears

accept ‘loud sounds can damage the ear’

• loud sounds can burst the eardrum

accept ‘it could make him deaf’accept ‘they are very loud’

‘they are loud’ is insufficient as‘loud’ is given in the question

1 (L3)

(b) any one from

• the further the sound travels the quieter it gets

accept ‘the sound or energy spreads out’

• she was furthest away

accept ‘she was further away’ or ‘she was far away’accept ‘some of the sound is absorbed’

1 (L3)

• the speed of light is greater than the speed of sound

accept ‘sound travels more slowly’

• light travels faster than sound

accept ‘light travels faster’ accept ‘light gets there before sound’

1 (L4)

(d) (i) • light

1 (L3)

(ii) • sound

1 (L3)

(e) gravity

accept ‘weight’

1 (L4)

M6. (a) makes it vibrate with a higher frequency

accept ‘it has a higher frequency’or ‘it vibrates more quickly’donot accept ‘it vibrates more’

1 (L7)

(b) the ear drum vibrates with a greater amplitude

accept ‘it has a greater amplitude’or ‘larger vibrations’donot accept ‘it vibrates more’

1 (L7)

accept ‘they damage the nerve endings

or cochlea or the bones in the ear or ear drum’donot accept ‘they damage the ear’

M8. (a) vibrate

allow move more (vigorously) but not just move

dirt / muck / grit / rust / dust etc.

do not accept bacteria

(b) any one medical use eg

ignore incorrect biological detail

•scanning unborn babies

•destroying (kidney) stones

(c)(i) 2

(ii)C

[5]

M9. (a) sound / mechanical / longitudinal (wave )

any one from:

•above 20 000 hertz / 20kHz

•above (human) audible range

•cannot be heard by humans

(b) either

particles / molecules / fluid vibrate(s) (1)

(and) knock particles of dirt off the jewellery (1)

by the process of cavitation (1)

accept ‘formation and collapse of tiny bubbles’

which breaks up / releases dirt from the surface (1)

(c)either both pro

or both con

or one of each

either

two appropriate points gain 1 mark each

one appropriate point (and) appropriate qualification / amplification

examples

other mammals (sufficiently) similar to humans (1)

so results appropriate (1)

unethical to experiment on humans (1)

so it is better to experiment on mice (1)

knowledge / techniques will benefit humans (1)

and also other animals (1)

experiments were justified because ultrasound has proved useful (1)

[6]

M10. (a) (i)A, C and D

any order but all three required and no others

(ii)D and E

either order but both required and no others

(b) (i) 20000 (Hz) to 20 (Hz)

accept ‘19980 (Hz)’

or vice-versa

(ii) frequency (of dog whistle) too high (for humans to hear) / frequencyabove 20000 Hz

accept ‘it is ultrasound’

accept ‘sound from the whistle is ultrasonic’

reflection

correct order essential

(ii) detector

[7]

M11.(a) (i)porpoise

apply list principle

(ii)chicken

apply list principle

(b) (i) 20–20,000

allow (15–20) – (18 000–20 000)

(ii)busy road traffic

normal talking

whisper

any 2 or 3 correct for 2 marks, 1 correct for 1 mark

ignore vacuum cleaner

otherwise deduct 1 mark for each incorrect answer

for 1 mark accept as the loudness increases the time limit decreases

(ii)1 hour

[8]

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