Introduction to Sound and Waves
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Questions and Answers

What is the amplitude of a vibrating object?

  • The average position during vibration
  • The minimum distance from the rest position
  • The distance at which the object stops vibrating
  • The maximum distance from the rest position (correct)

Two oscillating objects are said to be in phase if they:

  • Vibrate at different frequencies
  • Have the same period and travel in the same direction (correct)
  • Pass through their rest position at different times
  • Have opposite directions

What is the period of the spring if it vibrates 15 times in 12 seconds?

  • 2.4 seconds
  • 12 seconds
  • 1.25 seconds (correct)
  • 0.8 seconds

If an object has an amplitude of 1.2 m from its vertical rest position, how far will it travel in 3 complete cycles?

<p>14.4 m (D)</p> Signup and view all the answers

What happens when two oscillating objects have the same frequency but opposite directions?

<p>They are completely out of phase (C)</p> Signup and view all the answers

How is frequency defined in the context of a vibrating spring?

<p>The number of vibrations that occur in one second (D)</p> Signup and view all the answers

In the vibrating spring example, what was the frequency of the vibrations calculated?

<p>1.25 Hz (D)</p> Signup and view all the answers

What is the period of a pulse that beats 25 times in 15 seconds?

<p>0.6 s (D)</p> Signup and view all the answers

What is the frequency of a woman shoveling snow at a rate of 15 shovelsful per minute?

<p>0.5 Hz (A)</p> Signup and view all the answers

If an oscillating object has a frequency of 2 Hz, what is its period?

<p>0.5 seconds (A)</p> Signup and view all the answers

If a child on a swing completes 20 cycles in 25 seconds, what is the frequency of the swing?

<p>0.8 Hz (D)</p> Signup and view all the answers

Calculate the frequency of a tuning fork that vibrates 2.4 x 10^4 times in 1.0 minute.

<p>240 Hz (D)</p> Signup and view all the answers

What is the frequency of a violin string that vibrates 88 times in 0.20 seconds?

<p>440 Hz (D)</p> Signup and view all the answers

What is the period of a motor turning at 2450 rpm (revolutions per minute)?

<p>0.024 s (D)</p> Signup and view all the answers

How long does it take for the moon to complete one orbit around the earth if it orbits six times in 163.8 days?

<p>27.3 days (D)</p> Signup and view all the answers

What is the frequency of a physics ticker-tape timer that produces 3600 dots in 1.0 minute?

<p>60 Hz (C)</p> Signup and view all the answers

What does a 10 dB increase in sound intensity correspond to?

<p>A ten-fold increase (C)</p> Signup and view all the answers

At how many decibels is sound intensity considered painful to the human ear?

<p>130 dB (A)</p> Signup and view all the answers

If normal breathing has an intensity of 10 dB, what would the intensity be if it were 100 times louder?

<p>30 dB (A)</p> Signup and view all the answers

What is the threshold for hearing in decibels?

<p>0 dB (D)</p> Signup and view all the answers

Which of the following describes the relationship between decibels and intensity?

<p>A change of 10 dB results in a ten-fold increase in intensity (C)</p> Signup and view all the answers

How much more intense is a trumpet at 110 dB compared to a bell at 70 dB?

<p>1000 times more intense (C)</p> Signup and view all the answers

What is the typical safe range for sound intensity measured in decibels?

<p>85 dB (D)</p> Signup and view all the answers

What is the more common unit for measuring sound intensity?

<p>Decibels (dB) (A)</p> Signup and view all the answers

What is the term used for an object traveling at the speed of sound?

<p>Sonic (C)</p> Signup and view all the answers

What is the Mach number of an object flying at a speed of 1800 km/h where the speed of sound is 1060 km/h?

<p>1.7 (C)</p> Signup and view all the answers

What phenomenon occurs when an object travels through the sound barrier?

<p>Sonic boom (D)</p> Signup and view all the answers

What is the effect of an object traveling slower than the speed of sound?

<p>Is classified as subsonic (B)</p> Signup and view all the answers

Which speed indication is given to an object traveling faster than Mach 1?

<p>Supersonic (B)</p> Signup and view all the answers

At what altitude is the speed of sound given to be 1060 km/h in the example provided?

<p>10 km (C)</p> Signup and view all the answers

What is the typical effect produced by the sound wavefronts piling up in front of a plane traveling at the speed of sound?

<p>Sound barrier (B)</p> Signup and view all the answers

What do you hear when a train approaches at a frequency of 442 Hz and moves towards you?

<p>492 Hz (D)</p> Signup and view all the answers

What would the time be for a 200 m dash if measured from the sound of the starter's pistol?

<p>20.5 s (D)</p> Signup and view all the answers

How long does it take for sound to travel 1.4 km through air at 30 degrees Celsius?

<p>4 sec (D)</p> Signup and view all the answers

What is the time taken for sound to travel 600 m in steel?

<p>0.12 s (C)</p> Signup and view all the answers

Which factor does NOT affect the intensity of sound received by a human ear?

<p>Frequency of the sound (C)</p> Signup and view all the answers

How long does the fan hear the crack of the bat after the batter hits the ball, given the distance to the fan?

<p>0.29 s (B)</p> Signup and view all the answers

What is the relationship of sound waves as they propagate from the source?

<p>Spherical wave fronts (D)</p> Signup and view all the answers

What defines sound intensity in a more formal manner?

<p>Amount of power produced per unit area (B)</p> Signup and view all the answers

At 0 degrees Celsius, how much longer does sound take to travel 600 m in air compared to steel?

<p>1.68 s longer (A)</p> Signup and view all the answers

What does the Greek letter lambda (λ) represent in wave physics?

<p>Wavelength (D)</p> Signup and view all the answers

In the process of drawing a transverse wave, what does the amplitude represent?

<p>The height of the wave from the rest position (B)</p> Signup and view all the answers

What is the wavelength of a wave if two complete wavelengths measure 4.0 cm each?

<p>2.0 cm (D)</p> Signup and view all the answers

Which of the following best describes the Universal Wave Equation?

<p>It shows the relationship between energy, medium, wavelength, and frequency. (D)</p> Signup and view all the answers

How does a single oscillation of a wave source relate to wave formation?

<p>It creates a single crest or trough. (D)</p> Signup and view all the answers

What characterizes a periodic wave?

<p>It has repeating patterns in its structure. (C)</p> Signup and view all the answers

Which of the following statements is true concerning longitudinal waves?

<p>They consist of compressions and rarefactions. (A)</p> Signup and view all the answers

What is the amplitude of a transverse wave given that the wave has a height of 0.5 cm?

<p>0.5 cm (D)</p> Signup and view all the answers

Flashcards

Amplitude

The maximum distance that a vibrating object moves away from its resting position.

In Phase

Two oscillating objects are in phase if they have the same period and pass through their rest position at the same time.

Out of Phase

Two oscillating objects are out of phase if they have opposite directions, even if they have the same period and pass through their rest position at the same time.

Period

The time it takes for one complete cycle of vibration.

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Frequency

The number of complete cycles of vibration per second.

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Stroboscope

A device that produces flashes of light at regular intervals. It's used to study the motion of objects that move too quickly to be seen with the naked eye.

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Periodic Motion

The motion of an object that repeats itself at regular intervals.

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Wave

A disturbance that travels through a medium or space, transferring energy without transporting matter.

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Energy Transfer

The transfer of energy from one object to another without the transfer of matter.

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Power

The rate at which work is done or energy is transferred.

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Wavelength (λ)

The distance between two successive identical points on a wave, such as two crests or two troughs.

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Frequency (f)

The number of complete cycles of a wave that occur in one second.

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Wave Source

The source of the energy that creates a wave. It's what causes the initial disturbance.

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One Complete Oscillation

A complete cycle represents one full oscillation, which consists of a crest and a trough for a transverse wave.

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Transverse Wave

A wave that travels perpendicular to the direction of the energy transfer.

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Longitudinal Wave

A wave that travels parallel to the direction of the energy transfer.

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The Universal Wave Equation

The Universal Wave Equation relates the wave's velocity (v), frequency (f), and wavelength (λ): v = fλ.

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Sound Intensity

The amount of sound energy that hits a given point in space; formally defined as the amount of power produced per unit area (W/m^2).

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Factors affecting sound intensity

The intensity of sound received by a human ear depends on how powerful the sound source is and the distance from the source.

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Spherical Wave Fronts

Sound waves spread out from a source in spherical wave fronts, meaning they travel outward in all directions.

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Sound Intensity decrease with distance

As sound waves travel outward from a source, the surface area over which their energy is spread increases rapidly. This is why sound intensity decreases as you move further away from the source.

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Loudness

The loudness of a sound is determined by the sound intensity it produces.

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Power of the source

The energy a sound source produces.

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Distance from the source

How far a sound wave travels from the source to your ear.

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Mach number

The speed of an object relative to the speed of sound.

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Subsonic speed

The speed of an object that is slower than the speed of sound.

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Supersonic speed

The speed of an object that is faster than the speed of sound.

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Sound barrier

The barrier that forms when an object travels at the speed of sound, caused by the buildup of sound wavefronts.

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Noise cone

The cone-shaped region of compressed air that forms behind an object traveling at supersonic speeds.

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Sonic boom

The loud boom heard by observers when an object breaks the sound barrier.

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Doppler effect

A change in the frequency of a wave due to the relative motion of the source and the observer.

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Doppler effect: approaching source

The increase in frequency of a wave when the source is moving towards the observer.

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What is the threshold for hearing?

The threshold of human hearing. It's the sound intensity limit that a typical person with normal hearing can detect, it is roughly the sound level of a quiet whisper.

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What is the decibel scale?

A logarithmic scale that measures sound intensity. Each 10 decibel increment represents a tenfold increase in sound intensity.

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What is frequency?

The rate at which a sound wave vibrates. It's the number of cycles of vibration per second.

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What is loudness?

The perceived loudness of a sound. It's related to the amplitude of the sound wave, but also subjective, depending on the listener.

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What is wavelength?

The distance between two consecutive crests or troughs of a sound wave.

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What is sound intensity?

The amount of energy a sound wave carries. It's related to both the amplitude and frequency of the wave.

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What is pitch?

The subjective perception of frequency. Higher frequencies correspond to higher pitches, and lower frequencies correspond to lower pitches.

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What is loudness?

The perception of a sound's strength or power level. It's primarily determined by the intensity or amplitude of the sound wave.

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Study Notes

Introduction to Sound and Waves

  • Sound is a form of energy produced by vibrations.
  • Sound needs a medium (solid, liquid, or gas) to travel.
  • Sound travels fastest in solids, slower in liquids, and slowest in gases.

Wave Motion

  • A wave is a disturbance that transfers energy through a medium.
  • Transverse waves cause the medium to move perpendicular to the direction of the wave (e.g., water waves, light waves)
  • Longitudinal waves cause the medium to move parallel to the direction of the wave. (e.g., sound waves)

Measurements of Vibrations/Oscillations

  • Frequency is the number of cycles per second. (Measured in Hertz)
  • Period is the time taken to complete one full cycle.
  • Amplitude is the maximum displacement from the equilibrium or rest position.

The Universal Wave Equation

  • The speed of a wave (v) is equal to the product of its frequency (f) and wavelength (λ).
    • v = fλ

The Speed of Sound

  • The speed of sound varies depending on the medium and temperature.
  • Sound travels faster in warmer temperatures.
  • The speed of sound in air is approximately 343 m/s at 20°C.

The Intensity of Sound

  • Sound intensity (I) is the power per unit area.
  • The intensity of a sound decreases with distance from the source, following an inverse square law.

Reflection of Sound Waves

  • The angle of incidence equals the angle of reflection.
  • Echoes are reflections of sound waves.

The Doppler Effect

  • The Doppler effect is the apparent change in the frequency of a sound wave due to the relative motion between the source and the observer.
  • The frequency appears higher when the source is approaching and lower when the source is moving away.

Resonance in Air Columns

  • Resonance occurs when an object vibrates at its natural frequency.
  • For closed and open-ended columns, length of the column and the frequency of the sound wave determine if resonance will occur or not.
  • Certain frequencies can cause resonance in the column

Interference of Waves

  • Constructive interference occurs when waves combine to create a larger amplitude.
  • Destructive interference occurs when waves combine to create a smaller amplitude or even cancel each other out.

Beat Frequency

  • Beats are the periodic variations in the intensity produced when two sound waves with slightly different frequencies interfere.
  • Beat frequency can be calculated using the formula: fbeat = |f1 - f2|

Music & Musical Scales

  • Musical notes (tones) with simple integer ratios of frequencies produce consonant sounds.
  • An octave is a doubling or halving of the fundamental frequency.

Modes of Vibration

  • The fundamental mode is the simplest pattern of vibration.
  • Higher modes (harmonics, overtones) are more complicated patterns.

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IB Sound & Waves Booklet 2.1 - FILLED PDF

Description

This quiz covers the fundamental concepts of sound and wave motion. You will learn about the properties of sound, types of waves, and important measurements such as frequency, period, and amplitude. Dive into the universal wave equation and understand the factors affecting the speed of sound.

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