{"id":11679,"date":"2024-11-28T15:00:27","date_gmt":"2024-11-28T15:00:27","guid":{"rendered":"https:\/\/fisicaevestibular.com.br\/novo\/?page_id=11679"},"modified":"2024-12-03T14:16:02","modified_gmt":"2024-12-03T14:16:02","slug":"ondas-sonoras-en","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/ondulatoria\/acustica\/ondas-sonoras-en\/","title":{"rendered":"Sound Waves – EN"},"content":{"rendered":"

Sound Waves<\/span><\/b><\/p>\n

Acoustics<\/span><\/b><\/p>\n

Acoustics\u00a0<\/span>\"\"<\/b>Part of physics\u00a0<\/b>that studies\u00a0<\/b>sound and its various manifestations. More specifically,<\/b><\/span><\/b><\/b><\/b><\/b><\/p>\n

\"\"<\/p>\n

Physical acoustics studies the material part of the sound phenomenon,\u00a0<\/span><\/b>while\u00a0<\/span><\/b>psychoacoustics\u00a0<\/span><\/b>deals with the\u00a0<\/span><\/b>perception of the sound phenomenon by the senses.<\/span><\/b><\/p>\n

Wave physics\u00a0<\/span><\/b>is\u00a0<\/span><\/b>the part of physics\u00a0<\/span><\/b>that studies phenomena\u00a0<\/span><\/b>that present themselves\u00a0<\/span><\/b>in the form of waves\u00a0<\/span><\/b>and, as\u00a0<\/span><\/b>sound is the result of the perception of disturbances in the molecules of a medium\u00a0<\/span><\/b>in a certain space of time,\u00a0<\/span><\/b>these disturbances\u00a0<\/span><\/b>, in turn, present themselves in\u00a0<\/span><\/b>the form of waves\u00a0<\/span><\/b>as they\u00a0<\/span><\/b>propagate through the medium,\u00a0<\/span><\/b>and are\u00a0<\/span><\/b>called sound waves.<\/span><\/b><\/p>\n

Sound waves<\/span><\/b><\/p>\n

The\u00a0<\/span>pressure waves\u00a0<\/span><\/b>that characterize\u00a0<\/span><\/b>sound,\u00a0<\/span><\/b>called\u00a0<\/span><\/b>sound waves, are mechanical waves (\u00a0<\/b>they require a\u00a0<\/b>material medium to propagate)\u00a0<\/b>and longitudinal waves (\u00a0<\/b>the\u00a0<\/b>direction of vibration coincides with the direction of propagation).<\/b><\/span><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/p>\n

They do not propagate in a vacuum\u00a0<\/span><\/b>(there is no material medium for their propagation).<\/span><\/b><\/p>\n

They are\u00a0<\/span><\/b>produced by any vibratory movement\u00a0<\/span><\/b>and\u00a0<\/span><\/b>expand in space\u00a0<\/span><\/b>(three dimensions) by<\/span><\/b><\/p>\n

\"\"<\/p>\n

through\u00a0<\/span><\/b>compressions and rarefactions,\u00a0<\/span><\/b>until they reach\u00a0<\/span><\/b>our ears,\u00a0<\/span><\/b>where the\u00a0<\/span><\/b>eardrums, for<\/span><\/b><\/p>\n

\"\"<\/p>\n

resonance, are induced to vibrate at the same frequency as the source and cause us the physiological sensation of sound.<\/span><\/b><\/p>\n

The\u00a0<\/span><\/b>average range of audible frequencies\u00a0<\/span><\/b>for a\u00a0<\/span><\/b>normal human ear\u00a0<\/span><\/b>ranges from\u00a0<\/span><\/b>20Hz to 20,000Hz.<\/span><\/b><\/p>\n

Waves\u00a0<\/span><\/b>with\u00a0<\/span><\/b>frequencies lower than 20Hz are infrasound and higher than 20,000Hz are ultrasound.<\/span><\/b><\/b>\"\"<\/p>\n

<\/b>Infrasonic\u00a0<\/span><\/b>and\u00a0<\/span><\/b>ultrasonic waves are not audible to the human ear, but there are\u00a0<\/span><\/b>animals\u00a0<\/b><\/span>(\u00a0<\/span><\/b>moles and elephants, for example) that\u00a0<\/span><\/b>can capture infrasounds,\u00a0<\/span><\/b>being able to hear the\u00a0<\/span><\/b>waves from earthquakes\u00a0<\/span><\/b>(a few Hz).<\/span><\/b><\/p>\n

Ultrasounds\u00a0<\/span><\/b>can be heard\u00a0<\/b><\/span>by\u00a0<\/span><\/b>certain animals such as bats\u00a0<\/b>(up to 160,000 Hz)\u00a0<\/b>, dogs and<\/b><\/span><\/b><\/b><\/b><\/b><\/p>\n

\"\"<\/p>\n

cat\u00a0<\/span><\/b>(up to 40,000 Hz) and also\u00a0<\/span><\/b>used in medicine (echocardiography, obstetric ultrasound, etc.).<\/span><\/b><\/p>\n

Speed \u200b\u200bof sound<\/span><\/b><\/p>\n

Most\u00a0<\/span><\/b>sounds\u00a0<\/span><\/b>reach the\u00a0<\/span><\/b>ear transmitted\u00a0<\/span><\/b>through\u00a0<\/span><\/b>air\u00a0<\/span><\/b>(transmission medium), which,\u00a0<\/span><\/b>the denser it is, the better the transmitter,\u00a0<\/span><\/b>as\u00a0<\/span><\/b>the molecules are closer together, transmitting energy better\u00a0<\/span><\/b>from\u00a0<\/span><\/b>one to the other.<\/span><\/b><\/p>\n

For this\u00a0<\/span><\/b>reason,\u00a0<\/span><\/b>the\u00a0<\/span><\/b>speed of sound in solids\u00a0<\/span><\/b>is\u00a0<\/span><\/b>greater than in liquids,\u00a0<\/span><\/b>which in turn is\u00a0<\/span><\/b>greater than in gases. \u00a0<\/span><\/b>\u00a0\u00a0<\/b>\"\"<\/p>\n

The\u00a0<\/span><\/b>speed of\u00a0<\/span><\/b>sound propagation\u00a0<\/span><\/b>in a given medium depends on the temperature\u00a0<\/span><\/b>at which\u00a0<\/span><\/b>that medium is found.<\/span><\/b><\/p>\n

Thus, there is\u00a0<\/span><\/b>an\u00a0<\/span><\/b>increase\u00a0<\/span><\/b>in the speed of sound propagation in a given medium\u00a0<\/span><\/b>when\u00a0<\/span><\/b>its temperature\u00a0<\/span><\/b>increases\u00a0<\/span><\/b>(\u00a0<\/span><\/b>greater agitation of the particles).<\/span><\/b><\/p>\n

This occurs in the\u00a0<\/span><\/b>temperature range close\u00a0<\/span><\/b>to room temperature.<\/span><\/b><\/p>\n

See in the table that, for example, the\u00a0<\/span><\/b>speed of sound in air at 0\u00a0<\/span><\/b>\u00b0<\/span><\/b><\/sup>\u00a0C (331 m\/s) is lower than that in air at 15\u00a0<\/span><\/b>\u00b0<\/span><\/b><\/sup>\u00a0C (340 m\/s).<\/span><\/b><\/p>\n

Comparison between the speed of sound and the speed of light<\/span><\/b><\/p>\n

\"\"<\/p>\n

Fundamental wave equation for a sound wave<\/span><\/b><\/p>\n

\"\"<\/p>\n

Due to its\u00a0<\/span><\/b>longitudinal nature\u00a0<\/span><\/b>, sound\u00a0<\/span><\/b>cannot be polarized,\u00a0<\/span><\/b>but as with\u00a0<\/span><\/b>any sound wave,\u00a0<\/span><\/b>other phenomena\u00a0<\/b>can occur\u00a0 , such as\u00a0<\/b>diffraction, reflection, refraction, interference and the Doppler effect.<\/b><\/span><\/b><\/b><\/b><\/b><\/p>\n

Sound reflection<\/span><\/b><\/p>\n

\"\"<\/p>\n

<\/b>Sound reflection\u00a0<\/span><\/b>is\u00a0<\/b><\/span>a\u00a0<\/span><\/b>phenomenon\u00a0<\/span><\/b>that occurs when\u00a0<\/span><\/b>sound\u00a0<\/span><\/b>that\u00a0<\/span><\/b>was propagating in a medium,<\/span><\/b><\/p>\n

hits a\u00a0<\/span><\/b>reflective surface and returns to the source medium.<\/span><\/b><\/p>\n

This\u00a0<\/span><\/b>phenomenon gives rise to echo and reverberation.<\/span><\/b><\/p>\n

Echo<\/span><\/b><\/p>\n

Echo\u00a0<\/span><\/b>is a\u00a0<\/b>phenomenon in which we can clearly hear a sound reflected by reflective obstacles, one or more times in succession\u00a0<\/b><\/span>.<\/span><\/b><\/b><\/b>\"\"<\/p>\n

Our ear\u00a0<\/span><\/b>can only\u00a0<\/span><\/b>distinguish two successive sounds\u00a0<\/span><\/b>in a time interval\u00a0<\/span><\/b>equal to or greater than 0.10 seconds.<\/span><\/b><\/p>\n

Since the\u00a0<\/span><\/b>speed of sound in air is 340 m\/s,\u00a0<\/span><\/b>we have that\u00a0<\/span><\/b>V = \u0394S\/\u0394t\u00a0\u00a0<\/span>\"\"<\/b>\u00a0 340=\u0394S\/0.1\u00a0\u00a0<\/span>\"\"\u00a0<\/b>\u0394S=34m\u00a0<\/span><\/b>(round trip).<\/b><\/span><\/b><\/b><\/p>\n

Thus,\u00a0<\/span><\/b>a person\u00a0<\/span><\/b>can hear the echo of their own voice\u00a0<\/span><\/b>if they are at least\u00a0<\/span><\/b>17m away from the reflective obstacle.<\/span><\/b><\/p>\n

Reverberation<\/span><\/b><\/p>\n

\"\"<\/p>\n

Reverberation\u00a0\u00a0<\/span>\"\"<\/b>occurs when direct and reflected sound overlap and arrive at the ear together\u00a0<\/b>,<\/b><\/span><\/b><\/b><\/b><\/p>\n

which occurs when the\u00a0<\/span><\/b>reflecting surface is less\u00a0<\/span><\/b>than 17m from the emitting source.<\/span><\/b><\/b><\/p>\n

Sounds\u00a0<\/span><\/b>decrease or increase\u00a0<\/span><\/b>in intensity and become indistinct,\u00a0<\/b>as\u00a0<\/b>many reflections reach\u00a0<\/b>the listener and he or she\u00a0<\/b>cannot distinguish one from the other.<\/b><\/span><\/b><\/b><\/b><\/b><\/b><\/b><\/p>\n

Sonar<\/span><\/b><\/p>\n

Sonar\u00a0<\/span><\/b>is a\u00a0<\/b>device that emits ultrasounds,\u00a0<\/b>which\u00a0<\/b>reach objects, are reflected and capture the echoes, allowing them to be located by measuring the time between the emission and reception of the sound, knowing the speed of propagation of sound in water.<\/b><\/span>\u00a0\"\"<\/b><\/b><\/b><\/b>\"\"<\/p>\n

Widely used in\u00a0<\/span><\/b>navigation guidance, providing the profile of the seabed and locating schools of fish.<\/span><\/b><\/p>\n

To obtain\u00a0<\/span><\/b>images of the external and internal parts of any object\u00a0<\/span><\/b>(ships, submarines, etc.)\u00a0<\/span><\/b>immersed in the seabed, sound must be used through the ultrasound sent by the sonar.\u00a0\u00a0<\/span>\"\"<\/b>\u00a0 The\u00a0<\/span><\/b>sound can pass through the surface of the sediments, penetrating them, and be able to<\/span><\/b><\/p>\n

define the geometry of the internal layers through the echoes,\u00a0<\/span><\/b>which arrive at\u00a0<\/span><\/b>different times at the receiver on the surface,\u00a0<\/span><\/b>thus obtaining a\u00a0<\/span><\/b>3D figure of the sunken element.<\/span><\/b>\"\"<\/p>\n

Light is not convenient,\u00a0<\/span><\/b>since it is\u00a0<\/span><\/b>attenuated\u00a0<\/span><\/b>(reflected or absorbed) in the\u00a0<\/span><\/b>first initial layers of sediments, not being able to penetrate them, and only the superficial shapes of the sediments would be visualized.<\/span><\/b><\/p>\n

\"\"<\/p>\n

The same happens when you\u00a0<\/span><\/b>want to study the internal parts of metals\u00a0<\/span><\/b>(material structure).<\/span><\/b><\/p>\n

Radar\u00a0<\/span><\/b><\/p>\n

Radar\u00a0<\/span><\/b>works like sonar,\u00a0<\/b>but\u00a0<\/b>instead of ultrasonic waves, it emits<\/b><\/span>\u00a0\"\"<\/b><\/b><\/b><\/b><\/p>\n

\"\"<\/p>\n

electromagnetic waves that are reflected by distant objects, thus allowing their location.<\/span><\/b><\/p>\n

Ultrasound or ultrasound\u00a0<\/span><\/b><\/p>\n

Ultrasound or ultrasound\u00a0\u00a0<\/span>\"\"<\/b>is a\u00a0<\/span><\/b>diagnostic method\u00a0<\/span><\/b>that allows\u00a0<\/span><\/b>, through echo\u00a0<\/span><\/b>, to see the\u00a0<\/span><\/b>movements produced by the<\/span><\/b>\"\"<\/p>\n

various organs within the body.<\/span><\/b><\/p>\n

When the\u00a0<\/span><\/b>ultrasound is placed, through the transducer,\u00a0<\/span><\/b>on the\u00a0<\/span><\/b>patient’s skin,\u00a0<\/span><\/b>the\u00a0<\/span><\/b>sounds\u00a0<\/span><\/b>it\u00a0<\/span><\/b>emits are reflected in the internal organs or structures and return as echoes,\u00a0<\/span><\/b>which are\u00a0<\/span><\/b>sounds\u00a0<\/span><\/b>that the\u00a0<\/span><\/b>transducer electronically modifies and transforms into images.<\/span><\/b><\/p>\n

 <\/p>\n

What you should know, information and tips<\/span><\/b><\/p>\n

\"\"\u00a0\u00a0Understand the\u00a0<\/span><\/b>above\u00a0<\/b><\/span>information\u00a0<\/span><\/b>about\u00a0<\/b>echo, reverberation, sonar, radar and ultrasound.<\/b><\/span><\/b><\/b><\/b><\/p>\n

\"\"\u00a0Sound waves\u00a0<\/span>\"\"<\/b>are\u00a0<\/span><\/b>mechanical waves\u00a0<\/span><\/b>(they require a material medium to propagate)\u00a0<\/span><\/b>that are longitudinal\u00a0<\/span><\/b>(the direction of vibration coincides with the direction of propagation).<\/span><\/b><\/p>\n

They do not propagate in a vacuum<\/span><\/b><\/p>\n

\"\"\u00a0The\u00a0<\/span><\/b>average range of audible frequencies\u00a0<\/span><\/b>for a\u00a0<\/span><\/b>normal human ear\u00a0<\/span><\/b>ranges from\u00a0<\/span><\/b>20Hz to 20,000Hz.<\/span><\/b><\/p>\n

Waves\u00a0<\/span><\/b>with\u00a0<\/span><\/b>frequencies lower than 20Hz are infrasound and higher than 20,000Hz are ultrasound.<\/span><\/b><\/b>\"\"<\/p>\n

<\/b>Infrasonic\u00a0<\/span><\/b>and\u00a0<\/span><\/b>ultrasonic waves are not audible to the human ear, but there are\u00a0<\/span><\/b>animals\u00a0<\/b><\/span>(\u00a0<\/span><\/b>moles and elephants, for example) that\u00a0<\/span><\/b>can capture infrasounds,\u00a0<\/span><\/b>being able to hear the\u00a0<\/span><\/b>waves from earthquakes\u00a0<\/span><\/b>(a few Hz).<\/span><\/b><\/p>\n

Ultrasounds\u00a0<\/span><\/b>can be heard\u00a0<\/b><\/span>by\u00a0<\/span><\/b>certain animals such as bats\u00a0<\/b>(up to 160,000 Hz)\u00a0<\/b>, dogs and<\/b><\/span><\/b><\/b><\/b><\/b><\/p>\n

\"\"<\/p>\n

cat\u00a0<\/span><\/b>(up to 40,000 Hz) and also\u00a0<\/span><\/b>used in medicine (echocardiography, obstetric ultrasound, etc.).<\/span><\/b><\/p>\n

\"\"\u00a0Comparison between the speed of sound and the speed of light<\/span><\/b><\/p>\n

\"\"<\/p>\n

\"\"\u00a0Fundamental wave equation for a sound wave<\/span><\/b><\/p>\n

\"\"<\/p>\n

\"\"\u00a0Frequency\u00a0<\/span><\/b>is a characteristic of the wave.\u00a0<\/span><\/b>If the\u00a0<\/span><\/b>source is the same, the\u00a0<\/span><\/b>frequency of the wave is the same as the\u00a0<\/span><\/b>source,\u00a0<\/b>regardless of the medium in which it is propagating.<\/b><\/span><\/b><\/b><\/b><\/p>\n

\"\"\u00a0\u00a0Echo \u00a0\u00a0<\/span>\"\"\u00a0<\/b>phenomenon in which\u00a0<\/span><\/b>we can clearly hear a sound reflected by reflective obstacles, one or more times in succession.<\/span><\/b><\/b><\/p>\n

Our\u00a0<\/span><\/b>ear can only distinguish two successive sounds in a time interval equal to or greater than 0.10 seconds.\u00a0<\/span><\/b>Thus, a\u00a0<\/span><\/b>person can hear the echo of their own voice if they are at least 17 m away from the reflecting obstacle.<\/span><\/b><\/p>\n

\"\"\u00a0Some\u00a0<\/span><\/b>interesting exercises\u00a0<\/span><\/b>so you can\u00a0<\/span><\/b>observe and understand the resolution:<\/span><\/b><\/p>\n

01-\u00a0<\/span><\/b>(UNESP-SP)\u00a0<\/b>In\u00a0<\/b>recent decades,\u00a0<\/b>cinema has produced\u00a0<\/b>countless science fiction films\u00a0<\/b>with scenes of space wars,\u00a0<\/b>such as Star Wars.<\/b><\/span><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/p>\n

\"\"<\/p>\n

\u00a0With the exception of 2001: A Space Odyssey,\u00a0<\/span><\/b>these\u00a0<\/span><\/b>scenes feature explosions with impressive bangs,\u00a0<\/span><\/b>as well as\u00a0<\/span><\/b>spectacular lighting effects,\u00a0<\/span><\/b>all\u00a0<\/span><\/b>in interplanetary space.<\/span><\/b><\/p>\n

a)\u00a0<\/span><\/b>Comparing\u00a0<\/span><\/b>Star Wars, which features sound effects and explosions,\u00a0<\/span><\/b>with\u00a0<\/span><\/b>2001: A Space Odyssey\u00a0<\/span><\/b>, which\u00a0<\/span><\/b>does not,\u00a0<\/span><\/b>which one\u00a0<\/span><\/b>is\u00a0<\/span><\/b>in accordance with the\u00a0<\/span><\/b>laws of physics? Justify.<\/span><\/b><\/p>\n

b)\u00a0<\/span><\/b>What about the\u00a0<\/span><\/b>light effects that everyone presents? Justify.<\/span><\/b><\/p>\n

Resolution:<\/span><\/b><\/p>\n

a) 2001: A Space Odyssey\u00a0<\/span><\/b>is in accordance with the laws of physics,\u00a0<\/span><\/b>as sound does not propagate in the vacuum of interplanetary space.<\/span><\/b><\/p>\n

b)\u00a0<\/span><\/b>Both\u00a0<\/span><\/b>are correct, as light propagates in a vacuum.<\/span><\/b><\/p>\n

02\u00a0<\/span><\/b>\u2013\u00a0<\/span><\/b>(ITA-SP)\u00a0<\/span><\/b>A gong is struck every 0.5 seconds\u00a0<\/b><\/span>using an electromechanical process\u00a0<\/span><\/b>. A\u00a0<\/b>person\u00a0<\/b>standing\u00a0<\/b>very close to the gong sees and hears the strikes simultaneously. If they move\u00a0<\/b>a little away from the gong, they\u00a0<\/b>start to hear the sound a little after it strikes;\u00a0<\/b>however, when the\u00a0<\/b>person is 172m away from the gong, the sound and image become simultaneous again.<\/b><\/span><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/b>\"\"<\/p>\n

Determine the\u00a0<\/span><\/b>speed of sound under the conditions of the experiment.<\/span><\/b><\/p>\n

Resolution:<\/span><\/b><\/p>\n

When,\u00a0<\/span><\/b>again, sound and image are simultaneous,\u00a0<\/span><\/b>the\u00a0<\/span><\/b>person will be hearing the sound of the previous blow,\u00a0<\/span><\/b>which will be traveling the\u00a0<\/span><\/b>distance of 172 m in 0.5 s.<\/span><\/b><\/p>\n

V = \u0394S\/\u0394t\u00a0\u00a0<\/span>\"\"<\/b>\u00a0 V=172\/0.5\u00a0\u00a0<\/span>\"\"\u00a0\u00a0<\/b>V = 344 m\/s.<\/span><\/b><\/p>\n

03-\u00a0<\/span><\/b>(MACKENZIE-SP)\u00a0<\/b>A\u00a0<\/b>blacksmith strikes\u00a0<\/b>an iron blade with a sledgehammer\u00a0<\/b>, at a uniform pace, every 0.9 s.<\/b><\/span><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/p>\n

An\u00a0<\/span><\/b>observer, far from this blacksmith, sees,\u00a0<\/span><\/b>through\u00a0<\/span><\/b>binoculars,\u00a0<\/span><\/b>the\u00a0<\/span><\/b>hammer hitting the iron and hears the sound of the blows simultaneously.<\/span><\/b>\"\"<\/p>\n

The\u00a0<\/span><\/b>speed of sound\u00a0<\/span><\/b>, under local conditions, is\u00a0<\/span><\/b>330 m\/s. Calculate\u00a0<\/span><\/b>the\u00a0<\/span><\/b>shortest distance between the blacksmith and the observer.<\/span><\/b><\/p>\n

Resolution:<\/span><\/b><\/p>\n

The\u00a0<\/span><\/b>sound reaches the observer with a delay\u00a0<\/span><\/b>and\u00a0<\/span><\/b>the sound and image\u00a0<\/span><\/b>will be\u00a0<\/span><\/b>simultaneous when the delay\u00a0<\/span><\/b>is a\u00a0<\/span><\/b>multiple of the period of the hammer blows,\u00a0<\/span><\/b>that is,\u00a0<\/span><\/b>every 0.9s, 1.8s, 2.7s, etc.<\/span><\/b><\/p>\n

In this case, the\u00a0<\/span><\/b>shortest distance occurs with a delay of \u0394t = 0.9 s.<\/span><\/b><\/p>\n

V = \u0394S\/\u0394t\u00a0\u00a0<\/span>\"\"<\/b>\u00a0 330 = \u0394S\/0.9\u00a0\u00a0<\/span>\"\"\u00a0\u00a0<\/b>\u0394S = 297 m.<\/span><\/b><\/p>\n

04-\u00a0<\/span><\/b>(FUVEST-SP)\u00a0<\/b>A\u00a0<\/b>speaker\u00a0<\/b>emits a\u00a0<\/b>sound whose frequency F\u00a0<\/b>, expressed in\u00a0<\/b>Hz\u00a0<\/b>, varies as\u00a0<\/b>a function of time t in the form F(t) = 1,000 + 200t.<\/b><\/span><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/b><\/p>\n

\"\"<\/p>\n

At a\u00a0<\/span><\/b>given moment, the speaker is emitting a sound with a frequency F\u00a0<\/span><\/b>1<\/span><\/b><\/sub>\u00a0= 1,080 Hz.<\/span><\/b><\/p>\n

At the\u00a0<\/span><\/b>same instant, a person P, standing at a distance D = 34 m from the speaker\u00a0<\/span><\/b>, is\u00a0<\/span><\/b>hearing\u00a0<\/span><\/b>a\u00a0<\/span><\/b>sound with a frequency F\u00a0<\/span><\/b>2<\/span><\/b><\/sub>\u00a0,\u00a0<\/span><\/b>approximately\u00a0<\/span><\/b>equal to how many Hz?\u00a0<\/span><\/b>(speed of sound in air = 340 m\/s)<\/span><\/b><\/p>\n

Resolution:<\/span><\/b><\/p>\n

Calculation of the\u00a0<\/span><\/b>instant at which the speaker is emitting sound with frequency F\u00a0<\/span><\/b>1<\/span><\/b><\/sub>\u00a0= 1,080 Hz<\/span>\"\"<\/b><\/p>\n

F(t) = 1000 + 200t\u00a0\u00a0<\/span>\"\"<\/b>\u00a0 1080 = 1000 + 200t\u00a0\u00a0<\/span>\"\"\u00a0\u00a0<\/b>t\u00a0<\/span><\/b>1<\/span><\/b><\/sub>\u00a0= 0.4 s.<\/span><\/b><\/p>\n

Calculation of the\u00a0<\/span><\/b>time interval that any sound with V = 340 m\/s emitted by the source takes to reach person P who is D = 34 m from the source\u00a0<\/span>\"\"V = \u0394S\/\u0394t\u00a0\u00a0<\/span>\"\"<\/b>\u00a0 340 = 34\/\u0394t\u00a0\u00a0<\/span>\"\"\u00a0\u00a0<\/b>\u0394t = 0.1s.<\/span><\/b><\/p>\n

Thus, the\u00a0<\/span><\/b>sound that is being heard by the person at instant t\u00a0<\/span><\/b>1<\/span><\/b><\/sub>\u00a0= 0.4s was emitted by the\u00a0<\/span><\/b>source at instant\u00a0<\/span><\/b>t\u00a0<\/span><\/b>o<\/span><\/b><\/sub>\u00a0= t\u00a0<\/b>1<\/b><\/sub>\u00a0\u2013 \u2206t = 0.4s \u2013 0.1s\u00a0<\/b>= 0.3s\u00a0<\/b>.<\/b><\/span><\/b><\/b><\/b><\/b><\/b><\/b><\/p>\n

The\u00a0<\/span><\/b>frequency of this sound is given by f = 1000 + 200 . 0.3\u00a0<\/span><\/b>F =\u00a0<\/b>1000 + 200. 0.3\u00a0\u00a0<\/b>F\u00a0<\/b>2<\/b><\/sub>\u00a0= 1,060 Hz.<\/b><\/span>\u00a0\"\"<\/b>\"\"\u00a0\u00a0<\/b><\/b><\/b><\/b><\/p>\n

Check out the suggested exercises!<\/span><\/a><\/h3>\n","protected":false},"excerpt":{"rendered":"

Sound Waves Acoustics Acoustics\u00a0Part of physics\u00a0that studies\u00a0sound and its various manifestations. More specifically, Physical acoustics studies the material part of the sound phenomenon,\u00a0while\u00a0psychoacoustics\u00a0deals with the\u00a0perception of the sound phenomenon by the senses. Wave physics\u00a0is\u00a0the part of physics\u00a0that studies phenomena\u00a0that present themselves\u00a0in the form of waves\u00a0and, as\u00a0sound is the result of the perception of disturbances in the molecules of a medium\u00a0in<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2325,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-11679","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/11679","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/comments?post=11679"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/11679\/revisions"}],"predecessor-version":[{"id":12068,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/11679\/revisions\/12068"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2325"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=11679"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}