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Exam Study - Y9 Semester 2 > Science - Energies > Flashcards

Science - Energies Flashcards

1
Q

Waves on water are called

A

Transverse waves.

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2
Q

In a compression wave,

A

…the moving particles move backwards and forwards in the same direction as the energy transfer.

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3
Q

Compression waves are also known as?

A

Longitudinal waves.

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4
Q

The material through which the waves travel is called?

A

the medium.

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5
Q

Sound is an example of?

A

A compression wave.

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6
Q

All sounds are caused by?

A

Vibrations.

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7
Q

Vibrations cause air to?

A

Compress.

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8
Q

As the ruler moves upwards.

A

A compression is creative as air particles above the ruler are pushed together.

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9
Q

Air particles below the ruler.

A

Spread out, creating a “rarefaction”

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10
Q

When the ruler moves downwards, a

A

Rare fiction is created above the ruler, while a compression is created below it. Each vibration of the ruler creates new compressions and rarefactions that replace those that are moving through the air.

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11
Q

State what frequency is.

A

Frequency of a vibration (or wave) is number of complete vibrations or waves made in 1 seconds.

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12
Q

The frequency of a sound wave is…

A

given by the number of compressions made in one seconds.

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13
Q

Frequency is measured in?

A

Hertz (Hz), a unit named after Heinrich hertz, the German physicist who, in 1887, was the first to detect radio waves.

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14
Q

1 hertz =

A

one vibration per second.

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15
Q

The note, Middle C, has a frequency of what?

A

256 Hz.

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16
Q

The frequency of a sound determines its

A

Pitch.

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17
Q

High-frequency vibrations produce

A

High pitches.

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18
Q

Low-frequency vibrations produce:

A

Low pitches.

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19
Q

In the case of transverse waves, for example, waves on the water, the wavelength is…

A

the distance between two crests, OR the distance between 2 corresponding points on neighbouring waves.

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20
Q

What is a crest?

A

The highest point of a wave.

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21
Q

In the case of a compression wave, the wavelength is…

A

…the distance between the centre of 2 neighbouring compressions, OR 2 neighbouring rarefactions.

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22
Q

Define wavelength.

A

The distance between two crests.

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23
Q

Define rarefaction.

A

Lowering the density of a wave. For example, air particles spreading out below a wave.

24
Q

What is the wavelength of the note Middle C?

A

1.3 Metres.

25
Q

What is the wavelength of sound made during normal speech?

A

0.05 - 2.5 metres.

26
Q

If the frequency (number of hertz) of a sound is increased, compressions become…

A

…closer together.

27
Q

Shorter wavelengths mean…

A

The pitch you hear is heightened.

28
Q

Lower frequencies produce longer wavelengths, and thus…

A

…lower pitched sounds.

29
Q

Define amplitude:

A

The amplitude of a wave is the maximum distance that each particle moves away from its usual resting position.

30
Q

Higher amplitudes correspond with

A

Louder sounds.

31
Q

Lower amplitudes correspond with…

A

Quieter sounds.

32
Q

What causes all sound waves?

A

The transmission of energy from one place to another.

33
Q

Describe the difference between a compression and a rarefaction.

A

Air particles are being pushed together above the wave, causing a compression.
Air particles below the wave spread out, causing a rarefaction.

If the waves move downwards, compressions and rarefactions switch places.

34
Q

What is the unit of frequency and what does it measure?

A

Hertz, and the amount of waves created per second.

35
Q

What quality of sound does a frequency measure?

A

Frequency is the number of complete waves made in 1 second.

36
Q

Is a Mexican wave, as seen among the crowds at some sporting events, a transverse wave of a compression wave?

A

It is a transverse wave, since particles in a transverse wave travel to the direction of energy transfer.

37
Q

Because sound is transmitted as a compression wave…

A

…it can only travel through a medium that contains particles that can be forced closer together or further apart.

38
Q

Sound cannot be transmittitted

A

Through a vacuum, since there’s no particles to move inwards and outwards.

39
Q

As sound travels through a medium…

A

…some of its energy is absorbed by the particles in the medium, and is not transmitted to neighbouring particles.

40
Q

Sound travels more efficiently through which sort of materials and why?

A

Elastic. Where materials like this allow particles to come back to original positions without losing much energy.

41
Q

The speed of sound in a particular medium depends on…

A

How close the particles are to each other, and how easy they are to push closer together.

42
Q

In liquids and solids, the speed is much…

A

…greater, since the particles are more close together.

43
Q

The speed of sound in air is…

A

…greater at high temperatures.

44
Q

At sea level in dry air about 0°C…

A

…speed travels at about 330 metres per second.

45
Q

At a temperature of 25°C, it is about.

A

350 metres per second.

46
Q

The speed of sound in air is…

A

…lower at high altitudes. At an altitude of 10,000 metres above sea level, it is about 310 metres per second.

47
Q

A knowledge of the speed of sound is used in

A

Sonar. (SOund Navigation And Ranging).

48
Q

Sonar is commonly used on…

A

Ships. To match the ocean floor, detect schools of fish, and locate other underwater objects such as shipwrecks and submarines. High-frequency sound is transmitted from the ship.

49
Q

By measuring the time taken for the echo to return to the ship, and using the speed of sound in the water…

A

…the distance to the floor if the I dab or to the underwater object can be calculated.

50
Q

Sonar is an example of

A

Echolocation.

51
Q

List some animals which rely on echolocation.

A

Bats, whales, porpoises, dolphins. They each send out high-frequency sounds. The echo is detected and the animal’s brain processes the information to give it a “sound-image” of its surroundings.

52
Q

Echolocation is also used by engineers to

A

Locate cracks in metals, and itis used extensively in medicine (referred to as ultrasounds.)

53
Q

Ultrasound has frequencies higher than

A

humans can hear.

54
Q

Ultrasound is used in medicine to

A

Produce images of unborn babies in the womb during pregnancy, detect gallstones, destroy gallstones and kidney stones, circulation problems, treat en eye condition named called glaucoma, and cancers. The destruction and treatment of diseases is. Called named shock wave therapy. This can speed the healing of muscle damage, clean surfaces, mix paint, homogenise milk, and cut into glass and steel.

55
Q

Why are sound waves unable to travel through a vacuum?

A

There are no particles to bounce up and down.

56
Q

Suggest why the speed of sound depends on altitude and temperature.

A

If sound is produced in the air, there is little particles in the air for sound to rebound off of, since air consists of carbon dioxide, dry air, and hydrogen, which send sounds speeding at 260 - 1,300 metres per second. Sound travels faster underground, like in granite, for example, travelling at about 6,000 metres per second.

57
Q

A ‘wave’ is able to

A

Transmit energy from one place to another without moving any matter over the same distance.

Exam Study - Y9 Semester 2 (5 decks)

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