A vitamin pill covers all micronutrients. The macronutrients are:
Requirement Centrum g/day g Protein 50 0 Potassium 3.5 .08 Calcium 1.0 .2 Phosphorus 1.0 .02 Magnesium .35 .05Foods with high macronutrient density. Numbers in parts per thousand.
Phosphorus Potassium Calcium Magnesium Protein Sunflower seed 6.6 6.4 .8 3.3 179 Cheddar 5.1 1.0 7.2 .28 283 Peanut 3.8 7.1 .9 1.7 267 Beef 3.0 2.4 .12 .19 247 Turkey 2.1 3.0 .1 .21 293 Egg 1.9 1.3 .53 .12 120 Milk .9 1.4 1.1 .10 33 Potato .7 5.4 .15 .28 13 Rice .7 .8 .11 .23 52 Avocado .5 4.8 .1 .29 13The ultimate macronutrient food is sunflower seeds. The cheapest source of macronutrients is cheese and peanuts.
We calculate the price for food for 1 year. We assume 2600 calories/day.
Energy Price Efficiency Cal/kg $/kg Cal/$ Rice (dry) 3330 2.86 1160 Peanut 6000 6.60 910 Sunflower seed 5710 10.00 571 Chicken 2762 5.00 550 Milk 422 .80 530 Mountain Dew 440 1.00 440 Turkey 2429 6.00 404 Cheddar 4040 10.00 404 Beef 3380 9.00 375 Watermellon 300 .83 361 Egg 1400 4.00 350 Potato 930 2.84 327 Mozarella 2780 8.80 315 Palm oil 7353 24.00 306 Corn 860 4.40 195 Apple 579 5.00 115 Cucumber 154 2.00 77 Tomato 249 4.41 56 Lettuce 95 5.57 17 Cherry tomato 176 11.76 14Rice is the cheapest source of calories and peanuts are the cheapest source of macronutrients. You can feed a person for 2.5 $/day with rice, peanuts, and a vitamin pill.
The best insulator is air, which is why fluffy low-density materials like pillows and down coats are good insulators. The properties of a good coat are:
*) Thick. Insulation quality is proportional to thickness.
*) Low density Insulation quality is inversely proportional to density.
*) Full length.
The quality of thermal insulation is given by:
Material thickness = X Material thermal conductivity = C Insulation quality = Q = X/C
A layer of fluffy liner is far more insulating than a leather layer. Fluffy liner has a thermal conductivity not much larger than air.
Thickness Thermal Insulation Mass/Area conductivity quality mm Watts/K/meter Kelvin/meter2/Watt kg/meter2 Leather layer 1 .5 2 1 Fluffy liner 5 .025 200 .1
If you have a stout coat then most of your heat is lost through your legs. The next step is to use fluffy airtight snowpants.
Some common thermal conductivities are:
Watts/Kelvin/meter Steel 45 Granite 2.5 Glass .8 Water .6 Brick .5 Plastic .5 Plexiglass .2 Wood .1 Plastic foam .03 Air .025
The head generates heavy power and is easy to keep warm. One has to protect this heat with a hat. When resting,
Power Surface area Heat flux Watts meters2 Watts/meter2 Head 20 .13 160 Body 100 3 33
Insulation thickness = X meters Thermal conductivity = C Watts/Kelvin/meter Insulation quality = Q = X/C Kelvin meter2/Watt Temperature differential = T Kelvin Heat flux = F = CT/X = T/Q Watts/meter2
A heater can be built with a battery and a resistor. Example values:
Voltage = V = I R = 5 Volts Phone charging battery Resistance = R = 10 Ohms Current = I = .5 Amperes Power = P = V I = V2/R = 2.5 Watts
Large "power resistors" should be used. The larger the power, the larger the resistor has to be.
Resistors have a maximum power rating. If you use this power, the resistor won't melt but it will melt your coat. To make it coat safe, use 1/8 of the maximum power. In the above example where the resistor dissipates 2.5 Watts, a resistor rated at 20 Watts maximum should be used.
A USB wire can connect the battery to the resistor. A USB cable has 4 wires:
Red Positive voltage Black Zero voltage (ground) White Positive data Green Negaive data
The red and black wires carry power and the white and green wires carry data. Strip the red and black wires and connect them to the resistor. The USB end connects to the battery.
If multiple resistors are used then they should be connected in parallel.
Typical costs are:
$ Battery 10 5 Volts, 10 Amphours Resistor 2 10 Ohms, 20 Watt maximum USB wire 2 Solder 2 For connecting wiresWires can be connected with solder. A lighter can melt solder and so you don't need a soldering iron.
The larger the power dissipated by the resistor, the larger the resistor has to be. Values for commercial power resistors:
Power Length Width Depth Mass Power/Area Watts mm mm mm g Watts/cm2 5 22 10 10 5 .46 Ceramic 10 48 10 10 11 .47 Ceramic 20 62 12 12 19 .61 Ceramic 50 48 15 15 23 1.9 Aluminum 100 60 16 16 2.9 Aluminum
Voltage = V Volts Current = I Amperes Time = T seconds Charge = C = I T Amp seconds Power = P = V I Watts Energy = E = P T = C V Joules
Commerical batteries from Amazon:
Brand Price Charge Voltage Energy Current Power AC $ Amphour Volts Watthour Amps Watts Expertpower 11 10 5 50 3 15 No Expertpower 16 20 5 80 5 25 No Qualcomm 28 10 12 120 1.5 18 No Talent 50 8 12 96 6 72 No Libower 60 15 24 360 2.5 60 No 100percent 30 11 5 55 Yes AC: 120 Volt AC
Numbers are usually expressed in hours rather than seconds. For example,
Energy = 1 Watt hour = 3600 Watt seconds = 3600 Joules
Hydroponics is the technique of growing plants in water rather than soil, where the water is fertilized with nutrients. Hydroponics can yield 100 times as much food as soil-based agriculture, and a person can be sustained with only 200 square meters of hydroponics.
Hydroponics is easy. One can buy a system that takes care of everything and one need only supply the system with water and fertilizer. One can further improve yield with greenhouses, lighting, and mirrors.
A "grow kit" takes care of supplying the plants with water. One need only supply the kit with water and fertilizer. Fertilizer comes in powder form and dissolves in the water. Kits cost $2 per plant site.
Putting a greenhouse around the kit amplifies the yield by allowing one to control temperature and humidity. A greenhouse also allows plants to be grown during the winter.
Mirrors can amplify the sunlight reaching the planet, and mirror film is cheap.
Lights can improve the growth rate and make it possible to grow plants 24 hours.
A hydroponics system can be ordered online from places such as Amazon and Wallmart, and examples of costs are:
$ Amazon link Grow kit, 11 sites 25 * Grow kit, 90 sites 160 * Fertilizer, 10 kg 13 * LED grow light, 1000 Watts 140 * Mirror film, 400 square feet 24 * Greenhouse 120 *
1 kg of nutrient powder is mixed with ton of water. The composition of a typical nutrient solution is
Parts per million Potassium 160 Nitrogen 150 Calcium 100 Phosphorus 40 Sulfur 40 Magnesium 30 Iron 2 Manganese .5 Zinc .3 Boron .2 Copper .1 Molybdenum .075Source
Yield Yield Energy kCal/m2/yr kg/m2/yr Cal/kg Potato 48 52 923 Onion 20 50 400 Tomato cherry 17.2 98 176 Blueberry 13.8 24 573 Cucumber 12.6 82 154 Tomato 12.4 50 249 Lettuce 7.0 74 95
Hydroponics offers gains over field agriculture in many categories. The following table shows the amplification for each category in terms of hydroponic yield over field yield. The total amplification is the product of the amplification from each category.
Plant density 8 In terms of plants/meter2 Crops per year 4 Crop variety 2 Temperature contro l 2 LED lighting 2 Carbon dioxide enhancement 1.5
Soil mass yield = 1 grams/meter2/day Data Hydroponic mass yield = 100 grams/meter2/day Data Typical food energy density =1000 Calorie/kg (Potato = 930 Cal/kg) Hydroponic calorie yield = 100 Calorie/meter2/day Calorie requirement per day =2600 Calorie/day Hydroponic area/person = 26 meters2 (Area required to sustain one person) Hydroponic yield/growsite = 4 kg Electricity cost = 30 MJoules/$ Minimum water flow rate = .5 Litre/minute Optimal water flow rate = 1 Litre/minute Maximum water flow rate = 2 Litre/minute Maximum pipe length = 10 meters (If longer, nitrogen becomes depleted) Grow kit cost = 2 $/growsite Largest kit size = 72 growsites Nutrient solution cost = 13 $/kg (solid form) Water requirement = 500 kg of water per kg of solid nutrient fertilizer LED lamp cost = 7 Watts/$ Mirror film cost = 1.5 meter2/$ Transparent acrylic sheets = 32 $/meter2 Greenhouse cost (sturdy) =.016 meters3/$ (Plexiglass. Survives high wind) Greenhouse cost (unsturdy) =.18 meters3/$ (Plastic. Cannot survive high wind) O2 solubility in H2O, 10 C =11.2 mg/Litre O2 solubility in H2O, 20 C = 9.1 mg/Litre O2 solubility in H2O, 30 C = 7.2 mg/Litre O2 density in the atmosphere= 280 mg/LitreThe water pipes should exclude light to prevent algae growth.
The most efficient plant for converting sunlight to food energy is sugar cane, which has an efficiency of 7%. If LED lights are used to grow food for 1 person then the electrical power required is:
LED light efficiency = Ql = .2 Sugar cane efficinecy = Qc = .07 Plant efficiency = Qp = .5 Efficiency relative to sugar cane Total efficiency = Q = QlQcQp = .007 Human power = P = 120 Watts LED power = p = P/Q =17000 Watts Electric energy/dollar = c = 40 MJoules/$ Electricity cost for 1 year= C =12750 $
Arizona solar intensity, peak =1000 Watts/meter2 (Noon in mid-summer) Arizona solar intensity, ave. = 250 Watts/meter2 (Averaged over day and night) Manhattan solar intensity, ave.= 155 Watts/meter2 Electricity cost per Joule = 36 MJoules/$ Energy in one day =13.4 MJoules/day/meter2 Cost for one day = .37 $/day/meter2
A greenhouse can be cooled by evaporating water.
Melting energy of water at 0 Celsius = 334 kJ/kg Vaporization energy of water at 100 Celsius = 2257 kJ/kg Energy to raise water from 0 to 30 Celsius = 126 kJ/kg Total energy for melting ice = 2717 kJ/kg
1 Calorie = 4184 Joules Daily requirement for men = 2600 Calories Daily requirement for women = 2000 Calories
Prefabricated homes can be made from shipping containers, which are abundant, cheap, and easily delivered.
$ Length Width Height Mass ft ft ft kg 10-foot shipping container 1000 10 8 8.5 1300 20-foot shipping container 1200 20 8 8.5 2200 40-foot shipping container 1500 40 8 8.5 3800 Typical mobile home 90 18
Not all benches are created equal. Care must be taken in designing a bench that is comfortable.
The higher the back of the bench, the better. Best of all is if the bench can
support the back of your head.
Benches with curvature are more comfortable than flat benches.
There should be space underneath the bench for your feet.
There should be a canopy for rain, with side walls to shield against wind.
There should be benches in the sun for cold weather and benches in the shade for hot weather.
Benches should have arm rests.
Electric vehicles outperform gasoline vehicles in all regards except range, and if you splurge on the battery you can have the range (and ludicrous power). Electric vehicles are more powerful, quieter, simpler, more flexible, and cheaper than gasoline vehicles, and you can put an electric motor on anything, even a rollerblade. Electric power is ideal for compact and cheap city vehicles.
To give a sense for the strength of human and electric power,
kiloWatts Human unstrenuous cycling .1 Human strenuous cycling .3 Human sprint cycling 1 Typical electric bike 1 Monster electric bike 6 Typical car 100Electric power opens the way for light cheap city vehicles. Electric power easily has the speed and range for city driving.
To give a sense for the relationship between power and top speed,
Power Speed Speed kWatt m/s mph Bike .12 7 17 Human unstrenuous cycling Bike .25 9 21 Human strenuous cycling Bike 1 15 33 Human sprint cycling Bike 2 19 42 Bike 4 24 53 Trike 1 12 26 Trike 4 19 42 Trike 16 30 67 Car 16 26 58 Minimum power for cities Car 32 33 73 Minimum power for highways Car 64 41 92 Minimum power for freeways Car 128 52 116 Typical car Car 512 82 184 Sports car
Typical values for a 16 kWatt car battery are:
Energy/Mass = e = E/M = .8 MJoules/kg Power/Mass = p = P/M = 1.2 kWatts/kg Energy/Cost = c = E/C = .01 MJoules/$ Power/Cost = d = P/C = .012 kWatts/$ Energy/Power = D = E/P = .67 MJoules/kWatt Mass = M = = 13 kg Energy = E = = 11 MJoules Power = P = = 16 kWatts Cost = C = = 1330 $
Air drag determines a vehicle's top speed, energy use, and minimum battery power. A 16 kWatt car with a minimalist battery has a range of 30 km when driving at a speed of 20 meters/second.
Air density = D = 1.22 kg/meter3 Air drag coef. = K = .75 meters2 Car speed = V = 20 meters/second Air drag force = F = K D V2 =366 Newtons Air drag power = P = K D V3 = 7.3 kWatts Battery energy = E = 11 MJoules Distance traveled = X = E/F = 30 km
The goal is to minimize the energy cost per person. For an N-person vehicle,
People = N Distance traveled = X Air drag force = F Energy = E = F X Energy efficiency = Q = E/(NX) = F/NThe energy efficiency is equal to the air drag force divided by the number of passengers. Example values for various vehicles:
Speed Power Force Force/prsn People Range Drag area m/s kWatt Newton Newton km m2 Skate 10 .18 18 18 1 5 .3 Kick scooter 10 .18 18 18 1 5 .3 Bike 15 .82 55 55 1 8 .4 Car, small, city speed 20 4.9 244 244 1 10 1 Car, large, freeway speed 30 33 1100 1100 1 15 2 Bus, freeway speed 30 99 3290 46 72 15 6 Train car, freeway speed 30 99 3290 27 120 15 6 Airbus A380 251 251000 1000000 1840 544 10000 160 1 Horsepower = 746 WattsA full bus is 5 times more efficient than a compact car, but buses are rarely full and usually slow.
Buses and trains are substantially more efficient than planes and should be favored over short flights.
Trains are not substantially more efficient than buses and they are far less flexible.
Electric bikes are easy to make. All you have to do is replace a conventional wheel with an electric wheel and attach a battery pack. Electric wheels come in kits and you can make the battery pack yourself. Example configurations for various motor powers:
Power Max Range Motor Battery Battery speed cost cost energy kWatt mph miles $ $ MJoule .75 30 10 160 40 .5 1.5 35 20 240 60 1.2 3 45 40 570 100 1.8 6 55 80 1150 200 3.6The bikes have one electric wheel and one conventional wheel except for 6 kWatt bike, which has 2 electric wheels with 3 kWatt each.
Electric wheel prices are from Amazon.com.
Speed Power License mph kWatt required? Connecticut 30 1.5 Yes California 28 .75 No Massachusetts 25 .75 Yes Oregon 20 1.0 No Washington 20 1.0 No Pennsylvania 20 .75 No Delaware 20 .75 No Maryland 20 .5 No DC 20 ? No
A typical solar farm costs 5 $/Watt and produces 30 MWatts/km2, and America's electricity requirement can be satisfied by a farm that is 5% the size of Arizona. The largest farms are:
GWatts km2 MWatts/km2 B$ $/Watt California Solar Star .58 13 45 California Topaz .55 25 22 2.5 4.5 Thin film CdTe California Desert Sunlight .55 16 34 Thin film CdTe China Longyangxia Dam .32 9 36 California Cal. Valley Solar Ranch .29 8 36 1.6 5.5 Silicon crystal Arizona Agua Caliente Solar Project .29 10 29 1.8 6.2 Thin film CdTe Solar power capacity (GWatts) World 139 Germany 38.2 China 28.2 Japan 23.3 Italy 18.5 USA 18.3 France 5.7 Spain 5.4 UK 5.1 Australia 4.1
American solar farms tend to be in California or Arizona where sunlight is abundant. We calculate the payback time for a typical 1 meter2 solar cell in Arizona.
Solar cell efficiency = e = .20 Converting solar to electric energy Arizona solar intensity, peak = Ipeak = 1000 Watts Noon in mid-summer Arizona solar intensity, ave. = Iave = 250 Watts Averaged over day and night Solar cell peak power = Ppeak = e Ipeak= 200 Watts Solar cell average power = Pave = e Iave = 50 Watts Solar cell operation time = T = 2.3 years Payback time Solar cell energy generated = E = Pave T = 3622 MJoules Electricity cost per Joule = Qelec =2.8⋅10-8 $/Joule = .10 $/kWh Value of electricity generated= Celec = E Qelec= 100 $ Solar cell cost = Ccell = 100 $ Solar cell cost per peak Watt = Qcell =Ccell/Ppeak= .50 $/WattSetting the cost of the solar cell equal to the value of the energy generated,
Ccell = Celec = e Iave T Qelec Payback time = T = Ccell / (e Iave Qelec) = 2.3 yearsA solar farm in Arizona large enough to supply all of America's electricity is a square 120 km on a side, which is 5% of the area of Arizona.
U.S. total power = 3000 GWatts U.S. electric power = 500 GWatts U.S. solar power = 21 GWatts U.S. power/person = 9400 Watts U.S. population = 320 million Solar farm power per area = 35 MWatts/km2 (Typical solar farm) Solar farm area = 14300 km2 Arizona area =295234 km2 Solar farm side length = 120 km (Assume a square)
The types of solar cells are:
Technology Efficiency $/Watt Market frac Key element Element cost ($/kWatt) Thin film Ga As .29 Gallium Crystalline Si (mono) .25 .50 .36 Silver 48 Crystalline Si (poly) .20 .50 .55 Silver 100 Thin film Cu In Ga Se .20 .02 Indium Thin film Cd Te .16 .051 Tellurium 5 Thin film Amorphous Si .11 .02 - Multi junction .41 Gallium World record .44 Energy cost of silicon crystal= 39.6 MJ/kg Electricity cost = 36 MJ/$ Silicon crystal cost = 1.1 $/kg Monocrystal silicon = 6.0 kg/kWatt Monocrystal silicon cost = 6.6 $/kWatt Crystal silicon thickness = .18 mm Thin film (CdTe) tellurium = .093 kg/kWatt = 4.6 $/kWatt Silicon-monocrystal silver = .05 kg/kWatt = 48 $/kWatt = 100 $/kg = .0096kg/m2 Silicon-polycrystal silver = .10 kg/kWatt = 100 $/kWatt = 1000 $/kg = .020 kg/m2 Price of silver = 264 $/kg
A solar cell system requires an inverter to convert DC to AC power. For a 1 meter2 cell,
Solar cell efficiency = e Peak power = Ppeak = e Ipeak = 200 Watts Cost of inverter per peak Watt = Qinv = .15 $/Watt Cost of inverter = Cinv = Qinv Ppeak = 15 $ Cost of solar cell = Ccell = 100 $ Total system cost = Ctotal = 200 $The the inverter costs less than the solar cell.
We give thanks to Broadway Presbyterian Church, Starbucks, and Morning 2 Midnight.
The properties of the best commercial lithium ion batteries are:
Energy/Mass = .8 Joule/kg Power/Mass = 1200 Watt/kg Energy/$ = .01 MJoule/kg Density = 3.5 gram/cm3 Recharges =1000 Shelf life = 1.0 year Voltage = 3.7 VoltEnergy/Mass and Power/Mass are an engineering tradeoff. One can be increased at the expense of the other.
Energies and powers are for lithium batteries, which have a voltage of 3.7 Volts. The "ID #" is often used instead of cell size.
Cell Energy Power Current Mass Diameter Length Charge Price ID # size kJoule Watt Ampere gram mm mm AmpHour $ D 107 220 60 138 32 67 8.0 13 32650 C 67 220 60 92 26 50 5.0 8 26650, 25500 B 58 160 45 72 22 60 4.5 5 21700, 20700 A 47 110 30 49 18 50 3.5 3 18650 AA 9 22 6 15 14 53 .70 1 14500 AAA 4.7 11 3 7.6 10 44 .35 .5 10440 AAAA 2.3 6 1.5 3.8 8 42 .17 .25 75400
A single battery is a "cell" and a set of cells is a "pack". Packs are used to multiply the energy and power of cells.
Battery packs are notorous for catching fire, but cell technology has reached the point where it's now possible to make safe battery packs, and the design is simple enough so that anyone can construct their own packs.
Cells can be combined in series and/or parallel. Connecting in series multiples voltage, and voltage is helpful for achieving high power in a motor.
Connecting in series is easier than in parallel. If it's possible to achieve the required power without parallelization then one should do so, and this is usually possible with modern cells.
Series packs have the advantage that the cells can easily be extracted and charged individually, and cells can be interchanged between packs. One can also construct a set of series packs and swap them in like gun clips.
High power electric bikes use a voltage of 72 Volts. If we use one series array of C cells then a pack provides 4440 Watts and 1.2 MJoules. Any electric device requiring less than this much power can be powered by a series pack.
The properties of a modern high-power cell are:
Type = "C" Voltage = 3.7 Volts Energy = 60 kJoules Power = 155 Watts Mass = 92 grams Energy/mass = 650 kJoules/kg Power/mass =1680 Watts/kg Current = 42 Amperes Manufacturer = "Basen"When the cells are connected in series the values for voltage and power are:
Cells Voltage Power Volts kWatts 1 3.7 .15 2 7.4 .30 3 11 .45 Electric kick scooter 4 15 .60 6 24 .90 Electric bike 10 36 1.5 20 72 3.0 Compact electric car 96 356 15.0 Large electric car
Electric bike motors use either 36, 48, or 72 Volts. The following table shows how to build a battery pack for each motor power.
Power Volts Cells Series Parallel Current Cell max Cell Cell Cell Cell brand kWatt Amperes Amperes Amphours $ type .75 36 10 10 1 21 30 2.0 5 A Sony VTC4 1.5 48 13 13 1 31 60 4.5 8 C Basen 3 72 20 20 1 42 60 4.5 8 C Basen 6 72 40 20 2 83 120 4.5 8 C Basen 12 72 80 20 3 167 180 4.5 8 C Basen Cells Total number of cells, equal to the number of cells connected in series times the number of cells connected in parallel. Series Number of cells connected in series. For example, 20 batteries with 3.6 volts each connected in series produces a voltage of 72 Volts. Parallel Number of cells connected in parallel. Current Current required to provide given power Cellmax Maximum current of a cell
The Gigafactory in Nevada has a production target for 2020 of:
Battery production = 200 TeraJoules/year Energy of one car = 310 MJoules (Tesla Model S) Cars supplied/year = .64 millionThe Solar City Factory produces solar panels.
Panel production = 1.0 GWatts/year Panel duty factor = .25 (Average solar intensity over peak solar intensity) Effective power production = .25 GWatts/year
Cost of electricity = 30 MJoules/$ Crop time = 3 Mseconds = 40 days Lamp power =1000 Watts Lamp energy per crop = 3 GJoules/crop Lamp energy cost per crop = 100 $/crop
The following table shows the elemental composition of a typical hydroponic nutrient solution in parts per million.
Nitrogen 600 Calcium 400 Sulfur 400 Potassium 250 Magnesium 80 Phosphorus 80 Iron 4 Boron 2 Nickel 1 Manganese .8 Zinc .5 Copper .5 Molybdenum .01Hydroponic fertilizer can be purchased in solid form for $12/kg on Amazon.com. One kg of solid fertilizer supplies 500 kg of water.
The left column is the change in decibel level provided by soundproofing.
Decibels 25 Normal speech can be understood quite easily and distinctly through wall 30 Loud speech can be understood fairly well, normal speech heard but not understood 35 Loud speech audible but not intelligible 45 Loud speech not audible 50 Very loud sounds such as musical instruments or a stereo can be faintly heard; 60 Most sounds inaudibleTable for the reduction in intensity of sound for various kinds of walls. Values in decibels.
33 Typical interior wall 46 6 inch hollow concrete masonry 50 10 inch hollow concrete masonry
Sound transmission through the wall depends on the thickness of the wall.
L = Thickness of a wall Dair = Density of air Dwall = Density of wall material P = Characteristic pressure fluctuation of a sound wave striking the wall V = Characterstic velocity fluctuation of a sound wave striking the wall T = Wave period F = Wave frequency = 1/T Vwall = Characteristic recoil velocity of a wall upon being struck by a sound wave V^2 ~ P / DairThe impulse per area delivered to the wall is
Impulse / Area ~ P T ~ Dair T V^2The impulse per area is equal to the momentum per area delivered to the wall
Dair T V^2 ~ Dwall L Vwall Vwall ~ (Dair/Dwall) V^2 / (LF)The wall recoil generates a sound wave on the other side of the wall with a characteristic fluctuation magnitude of Vwall. The decibel level is proportional to the logarithm of the velocity.
log(Vwall) = Constant - log(L) - log(F)The change in decibel level is proportional to the logarithm of the wall thickness. It's better to divide a wall into many layers rather than having one solid wall.
The change in decibel level is proportional to the logarithm of the frequency. Low-frequency waves are difficult to block.
If a sound wave strikes a wall then only a small fraction of the energy is transmitted through the wall. If an object strikes the wall then a substantial amount of energy is transmitted through the wall. Carpets are a big help for soundproofing.
Noise is often characterized with a power spectrum because the properties of soundproofing depend on frequency. It is easier to stop high-frequency noise than low-frequency noise.
The walls of an anechoic chamber absorb all sound.
The absorbers are pointy to minimize the reflection of sound.
The information rate for sound is kilobytes/second and the rate for vision is megabytes/second.