Geography 2152F/G Lecture Notes - Tunguska Event, Eiffel Tower, Infrasound

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svprxme12

13 Jan 2022

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Western University

Department

Geography

Course

Geography 2152F/G

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Infrasound: sound waves too low to hear. Deep base tones = huge amounts of energy, below human hearing. Clues - travel for a long time. low frequency soundwaves circled the world a few times from this blast. The stations with sensitive sensors that detected this were larger waves than ever seen before. Nasa: early warning want to find the asteroids. Tracking of known asteroids and finding new ones. Deploy more effective technology (infrared telescope in space: would orbit around the sun and allow us to detect earlier with more accuracy). Scan areas in space invisible from earth to survey sky of objects on collision courses.

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14.1. BIO (a) Music. When a person sings, his or her vocal cords vibrate in a repetitive pattern that has the same frequency as the note that is sung. If someone sings the note B flat, which has a frequency of 466 Hz, how much time does it take the person's vocal cords to vibrate through one complete cycle, and what is the angular frequency of the cords? (b) Hearing. When sound waves strike the eardrum, this membrane vibrates with the same frequency as the sound. The highest pitch that young humans can hear has a period of 50.0 us. What are the frequency and angu- lar frequency of the vibrating eardrum for this sound? (c) Vision. When light having vibrations with angular frequency ranging from 2.7 X 10" rad/s to 4.7 x 101 rad/s strikes the retina of the eye, it stimulates the receptor cells there and is perceived as vis- ible light. What are the limits of the period and frequency of this light? (d) Ultrasound. High-frequency sound waves (ultrasound) are used to probe the interior of the body, much as x rays do. To detect small objects such as tumors, a frequency of around 5.0 MHz is used. What are the period and angular frequency of the molecu- lar vibrations caused by this pulse of sound?

I have written my answers in for the one i may of understood!Any help would be great even explanation on how to dothe parts....PLEASE HELP THANK YOU!!!!!!!!!

B. One can purchase so-called Ceramic speakers which haveavibrating ceramic instead

of a coil-driven cone to produce sound waves. These arecapableof producing

frequencies well above the range of human hearing and, infactare used for sonar and

ultrasound applications. The disks used have aconductivecoating applied to either side

of the disk and the ceramic material reacts to anappliedvoltage by contracting or

expanding by an amount proportional to the voltage.Thesedevices are capacitive rather

than inductive.

1. Write the expression for the impedance of such a speakerinterms of the resistance

and capacitance.

2. Find an expression for the frequency Ï at whichtheresistance equals the reactance of

the ceramic speaker, in terms of R and C.

3. With R = 8Î© and C = .25Î¼F, calculate thefrequency Ï, withunits, that will give R =

XC .

4. Using Ïo for the frequency you calculated in 3,calculatethe total impedance, Z, for

the following frequencies and plot the results on the logplotprovided.

Table

Ï/ Ïo 10-4 10-3 10-2 10-1 1 10 102 103 104

6. Locate your answer for part (2) on the plot. What featureofthe plot corresponds to

that answer? [4 points]

7. Describe how to quickly sketch this log-log plot for anRCcircuit with only one

calculation, based on your answer to (6). [5 points]

9. Using Ïo for the frequency you calculated in 3,calculatethe total impedance, Z, of the

LR circuit for the following frequencies and plot theresultson the log plot provided.

Table

Ï/ Ïo 10-4 10-3 10-2 10-1 1 10 102 103 104

) Ion Rocket Engine. A special type of rocket engine useselectricity for propulsion: the ion engine. A soft metal, such ascesium, is vaporized and then electrified (ionized) with highvoltage. These cesium ions are the accelerated by strong electricfields to produce a current of atoms at high velocity. Outside theengine, the ions are then recombined with electrons to restoreelectrical neutrality.

A particular ion engine has an exhaust velocity of 20,000 m/sec.The mass flow (dm/dt) is just 1 milligram per second.

a) What is the thrust produced by this engine?

b) The engine propels a 200 kg spacecraft. What velocity change(delta-v) is achievable by running the engine continuously for onesolid year? (For simplicity, assume a constant mass for the system.One year = 31.56 million seconds.)
---------------------------
) Potential Energy. How much work is required to lift one metricton (1000 kg) of water to an altitude of 1000 meters? (The Sun isdoing this all this time to the Earthâs weather.)
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q) Kinetic Energy 1. A car has a mass of 1200 kg. How much kineticenergy does it have when traveling at a speed of 30 m/sec?

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Kinetic Energy 2. The Space Shuttle orbits the Earth at a speed ofsome 7750 meters per second (which is about 260 times that of atypical highway driving speed). With a typical payload, the Shuttlehas a mass of 120,000 kg.

a) What is the kinetic energy of the Shuttle in orbit?
b) The Shuttle reaches orbit in some 500 seconds. At what rate ofwork (power) did the rocket engines perform on the Shuttle to placethe craft and its payload into orbit? Compare this to the maximumpower output of a typical nuclear electric generatingstation.
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Solar Power. In space, outside the atmosphere, some 1360 Watts ofradiant power pass through every square meter (at normalincidence).

a) What total amount of power does the Earth intercept from theSun? (The projected area of the Earth is ?RE2, where RE is theradius of the Earth, 6.38 million meters.)

b) Compare this figure to the total amount of power produced by allof human civilization, currently some 40 trillion (1012) Watts.What conclusions about solar power can you draw from thiscomparison?

q

-) Angular Momentum. Assuming a uniform distribution of mass insidethe Earth, calculate:

a) the Earthâs moment of inertia, I;
b) its angular momentum, L = omega(omega=2pi/T) the angularmomentum of the Moon in its orbit around the Earth (L = mvr).Compare these two values. (The sidereal period of the Moon is 27.3days; its mass is 1/81 of that of the Earth; its average orbitalradius is 383,000 km.)

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Q0 Water Pressure. Calculate the value of the water pressure at theChallenger Deep, the deepest known place on the surface of theEarth. The currently accepted depth of the water there is 10,911meters. (This is deep enough to cover Mount Everest, and still havemore than one mile of water above the peak. On January 23, 1960,Swiss explorer Jacques Piccard and US Navy Lieutenant Don Walshbecame the first, and so far, the only people ever to visit thisremote place, descending in the Italian-built bathyscaphTrieste.)

q-8
Mass of Earthâs Atmosphere. The pressure of the Earthâs atmosphereat sea level is 101,300 Pascals (Newtons per square meter.) Thismeans that every square meter of Earthâs surface supports a weightof 101,300 Newtons. From this, determine the mass of Earthâsatmosphere. What fraction of the Earthâs total mass is this?

Geography 2152F/G Lecture Notes - Tunguska Event, Eiffel Tower, Infrasound

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