Main site of science textbooks
Crowdfunding site for the free
online science textbooks project

Science fundamentals
Dr. Jay Maron

Units
One-second ticks

The fundamental units are the meter, second, kilogram, and Coulomb. They were originally defined in 1793 as the "Standard International" (SI) units, or "MKS" units.

```
Quantity   Unit       Definition

Length     Meter      The Earth's circumference is 40 million meters
Time       Second     There are 86400 seconds in one Earth day
Mass       Kilogram   The mass of a cube of water 10 cm on a side is 1 kilogram
Charge     Coulomb    The force between two charges of one Coulomb each and
separated by 1 meter is 9 billion Newtons

```
1 kg of water
1 kg of air
```Density of water  =1000   kg/meter$3$  = 1      g/cm$3$
Density of air    =   1.2 kg/meter$3$  =  .0012 g/cm$3$
```

Derived units

The fundamental units are length, mass, time, and charge, and all other units are derived from these.

```
Quanity                        Composition            Units

Length           = X                                  meters
Mass             = M                                  kg
Time             = T                                  seconds
Charge           = C                                  Coulomb
Speed            = V = X/T     Length / Time          meters/second
Momentum         = Q = M V     Mass   * Speed         kg meters/second
Acceleration     = A = V/T     Speed  / Time          meters/second2
Force            = F = M A     Mass   * Acceleration  Newtons =  kg meters/second2
Energy           = E = F X     Force  * Distance      Joules  =  kg meters2/second2
Power            = P = E/T     Energy / Time          Watts   =  kg meters2/second3
Area             = S = X2      Length$2$                meters$2$
Volume           = Υ = X3      Length$3$                meters$3$
Density          = ρ = M/Υ     Mass   / Volume        kg / meters2
Pressure         = Φ = F/S     Force  / Area          Pascals =  Newtons/meter$2$  =  Joules/meter$3$
Angular momentum = L = M V X   Momentum*Length        kg meters$2$/second
Torque           = Γ = F X     Force  * Length        kg meters$2$/second$2$
Frequency        = f = 1/T     1      / Time          Hertz   =  1/second
```

Unit conversions
```Meter        =   39.37  inches
=   1.0936 yards
=   3.281  feet
=   1/1609 miles
Mile         =   1609   meters
=   1760   yards   (exact)
Yard         =   3      feet    (exact)
=   .9144  meters
Foot         =   12     inches  (exact)
=   .3048  meters
Inch         =   25.4   mm      (exact)
Minute       =   60     seconds
Hour         =   60     minutes
Day          =   24     hours
Year         =   365.25 days
Ton          =   1000   kg         (exact)
Kilogram     =   1000   grams      (exact)
=   2.205  pounds     (pounds interpreted as mass)
Newton       =   .2248  pounds     (For Earth gravity at the surface)
(pounds interpreted as force)
Pound        =   16     ounces     (exact)  (interpreted as mass)
=   .4535  kg
4.448  Newtons    (interpreted as force)
Ounce        =   28.35  grams      (interpreted as mass)
Meter/second =   2.24   miles/hour
Km/hour      =   .6214  miles/hour
Miles/hour   =   1.609  km/hour
Pascal       =   .0001450 pounds/inch2   (pounds interpreted as force)
Pound/inch2  =   6895   Pascals
Bar          =   101325 Pascals    (Atmosphere pressure at sea level)
=   14.50  pounds/inch2     (pounds interpreted as force)
Earth gravity=   9.807  meters/second2
=   32.2   feet/second2
Standard sheet of paper  =  11 x 8.5 inches  =  27.94 x 21.59 cm
```

Magnitudes

Distance

Larger Picture
```                    Meters       Earth      Earth        Light travel
(AU)
Nucleus                2⋅10$-15$
Atom                   2⋅10$-10$
Green light            5.5⋅10$-7$
Neuron                    .00002
Dime thickness            .00135
Dime diameter             .0178
Quarter diameter          .024
Tennis ball diameter      .067
Soccer ball diameter      .22
Average person           1.78
Central Park width     800
Mount Everest         8848
Moon distance     3.844⋅108         60.3         .00257      1.5 seconds
Sun radius        6.957⋅108        109           .00474      2.3 seconds
Earth orbit       1.496⋅1011     23481          1.0          8   minutes
Jupiter orbit                                  5.2         40   minutes
Neptune orbit                                 30.1          3   days
Light year        9.461⋅1015                63241            1   year
Alpha Centauri                                              4.4 years      Nearest star
Galaxy thickness                                         1000   years
Galaxy center                                           27200   years
Galaxy diameter                                        100000   years
Andromeda distance                                       2.54   million years
Virgo cluster distance                                     54   million years
Size of universe                                           14   billion years
```
A photon traveling from the Earth to the moon

Speed

Cheetah
Needletail
Concorde
F-16 Falcon

F-15 Eagle
F-35 Lightning
F-22 Raptor
SR-71 Blackbird

```            meters/second   Mach

Walk                 1.5
Running sprint      10
Cycling sprint      20
Cheetah             30             Fastest land animal
70 miles/hour       31
Baseball pitch      45             100 miles/hour
Human neuron       100
Sound at altitude  295             Speed of sound at altitude 10 km to 20 km
747 airplane       266      .9
Sound at sea level 340     1.0     At sea level and 15 degrees Celsius
F-35 Lightning     475     1.6     Stealth fighter
F-16 Falcon        590     2.0
Concorde           606     2.05
F-22 Raptor        670     2.3     Stealth fighter
F-15 Eagle         740     2.5
SR-71 Blackbird    980     3.3
Orbit speed       7800    26.4     Minimum speed to orbit the Earth
Escape speed     11200    38.0     Minimum speed to escape the Earth's gravity
Ion rocket      100000             Fastest spacecraft we can build
Fission rocket     107
Fusion rocket      107
Light            3⋅108  1020000
```
Aircraft typical fly at altitude 10 km to 20 km, where the speed of sound is 295 m/s. Mach 1 for aircraft is defined using this speed.

Mass

```                       kg         Earth      Solar
masses     masses
Electron          9.109⋅10-31
Proton            1.673⋅10-27
Neutron           1.675⋅10-27
1 ounce                    .0283
Tennis ball                .058
Soccer ball                .44
1 pound                    .454
Typical human            67
Sumo wrestler           230
Ton                    1000
Honda Civic            1200
Elephant               5000
Argentinosaurus       70000                                   Largest dinosaur
Blue whale           200000
Moon               7.35⋅1022         .0123
Mars               6.42⋅1023         .107
Earth              5.92⋅1024        1
Jupiter            1.90⋅1027      318           .00096
Sun                1.99⋅1030   330000          1.0
White dwarf max     2.9⋅1030                   1.44
Milky Way black hole7.4⋅1036                   4.2 million
Milky Way           2.5⋅1042                   1.2 trillion
Andromeda           2.5⋅1042                   1.2 trillion
M87 galaxy                                   10   trillion
Virgo galaxy cluster                       1200   trillion
```

Coins

```            Mass  Diameter  Height  Density  Price/kg  Copper    Nickel     Zinc    Manganese
g       mm       mm     g/cm3     \$/kg   fraction  fraction  fraction  fraction

Penny        2.5     19.05   1.52    5.77       4.0     .025               .975
Nickel       5.000   21.21   1.95    7.26      10.0     .75      .25
Dime         2.268   17.91   1.35    4.62      44.1     .9167    .0833
Quarter      5.670   24.26   1.75    6.29      44.1     .9167    .0833
Half dollar 11.340   30.61   2.15    7.90      44.1     .9167    .0833
Dollar       8.100   26.5    2.00    7.53     123.5     .885     .02       .06      .035
Dollar bill  1.0              .11     .88    1000
```
The above objects are all to scale. The dimensions of a dollar bill are 155.956 mm * 66.294 mm * .11 mm.
For a coin,
```Mass     =  M
Diameter =  D
Height   =  H
Volume   =  Vol  =  π H D2 / 4
Density  =  M / Vol
```
The density of metals is:
```          Density   Price    Year of
g/cm3    \$/kg    discovery

Air          .0012
Water       1.0
Magnesium   1.74       2.8     1808
Aluminum    2.70       1.7     1827
Titanium    4.51      10       1910
Zinc        7.14       2.0     1300
Manganese   7.21       2.3     1774
Iron        7.9         .3    -1200
Nickel      8.91      15       1751
Copper      8.96       6      -5000
Silver     10.49     640    Ancient
Tungsten   19.25      50       1783
Gold       19.30   43000    Ancient
Platinum   21.45   37000       1735
Osmium     22.59   12000       1803   Densest element
```
Gold was the densest element known until the discovery of tungsten in 1783 and was hence valuable as an uncounterfeitable currency. Silver can be counterfeited with lead because lead is more dense and cheaper than silver.

The price of the metal in a penny is

```Metal price  =  Penny mass * (Copper fraction * Copper price/kg + Zinc fraction * Zinc price/kg)
=  .0025 kg   * (     .025              6 \$/kg           .975           2 \$/kg    )
=  .0052 \$
```
For a penny made of pure copper the price of the metal is 1.5 cents. A penny made of gold, silver, or zinc has a value of:
```       Price/Mass   Price
\$/kg        \$

Zinc        2        .005
Copper      6        .015
Silver    640       1.6
Gold    43000     108
```

Balls

Ball sizes are in scale with each other and court sizes are in scale with each other.
Ball sizes are magnified by 10 with respect to court sizes.
The distance from the back of the court to the ball is the characteristic distance the ball travels before losing half its speed to air drag.

```             Ball    Ball   Court   Court    Ball
diameter  Mass   length  width   density
(mm)    (g)     (m)     (m)    (g/cm3)

Ping pong      40      2.7    2.74    1.525   .081
Squash         40     24      9.75    6.4     .716
Golf           43     46                     1.10
Badminton      54      5.1   13.4     5.18    .062
Racquetball    57     40     12.22    6.10    .413
Billiards      59    163      2.84    1.42   1.52
Tennis         67     58     23.77    8.23    .368
Baseball       74.5  146                      .675  Pitcher-batter dist. = 19.4 m
Hockey puck    76    163     61      26      1.44   25 mm thick
Whiffle        76     45                      .196
Football      178    420     91.44   48.76    .142
Rugby         191    435    100      70       .119
Bowling       217   7260     18.29    1.05   1.36
Soccer        220    432    105      68       .078
Basketball    239    624     28      15       .087
Cannonball    220  14000                     7.9    For an iron cannonball
```

Density
```                  grams/cm2

Air on Mars         .00002
Air at Everest      .0004       10 km altitude
Air at Denver       .001        1 Mile altitude
Air at sea level    .00127
Ice                 .92
Water              1.0
Rock               2.5

Magnesium          1.7
Aluminum           2.7
Titanium           4.5
Iron               7.9
Silver            10.5
Gold              19.3
Tungsten          19.3
Osmium            22.6           Densest element

Earth              5.52
Moon               3.35
Mars               3.95
Europa             3.103
Ganymede           1.94
Callisto           1.83
Titan              1.88

Balsa               .12
Corkwood            .21
Cedar               .32
Pine                .37
Spruce, red         .41
Oak, red            .66
Hickory             .81
Bamboo              .85
Oak, live           .98
Ironwood           1.1
Lignum Vitae       1.26
```

Kilograms and pounds

For a 1 kg mass, Newton's law is:

```Mass                       =  M          = 1   kg
Gravitational acceleration =  g          = 9.8 m/s2
Gravitational force        =  F  =  M g  = 9.8 Newtons  =  2.203 pounds
```
The pound is a unit of force. 1 pound = 4.448 Newtons. In Earth gravity a mass of .454 kg produces a force of 1 pound.
```Mass                       =  M          =  .454 kg
Gravitational acceleration =  g          = 9.8   m/s2
Gravitational force        =  F  =  M g  = 4.448 Newtons  =  1 pound
```

Acceleration
```                    Meters/second2
Ceres gravity            .27
Europa gravity          1.31
Titan gravity           1.35
Moon gravity            1.62
Mars gravity            3.8
Venus gravity           8.87
Earth gravity           9.8
Bugatti Veyron         15.2  0 to 100 km/h in 2.4 seconds
Red out                30    Max long-term acceleration in the direction of blood rushing to your head
Blackout               50    Max long-term acceleration while sitting
Formula-1 car          50    High-speed breaking and cornering with a downforce wing
Blackout with g suit   90    Max long-term acceleration while sitting with a g-suit
Max long-term (front) 120    Max long-term acceleration while lying on one's front
Max long-term (back)  170    Max long-term acceleration while lying on one's back
Max short-term        500    Max short-term acceleration
Bullet             310000    9x19 Parabellum handgun, average acceleration along the barrel
```

Energy

Energies in MJoules = 106 Joules

```Raise 1 kg of water by 1 Kelvin   =      .00419 =  1 Food Calorie  =  1000 calories
Sprinting person                  =      .004       (80 kg moving at 10 m/s)
Phone battery                     =      .018       (5 Watt hours)
Laptop battery                    =      .180       (50 Watt hours)
1 kg of supercapacitors           =      .04
1 kg of Lithium battery           =     1.3
1 kg of TNT                       =     4.2
1 kg of sugar                     =    20     =  5000 Food Calories
1 kg of protein                   =    20     =  5000 Food Calories
1 kg of alcohol                   =    25     =  6000 Food Calories
1 kg of fat                       =    38     = 10000 Food Calories
1 kg of gasoline                  =    48     = 13000 Food Calories
Uranium fission bomb (Little boy) =   7⋅107    = 16 kilotons of TNT
Plutonium fission bomb (Trinity)  =   8⋅107    = 20 kilotons of TNT
Uranium fission bomb (Fat man)    =   9⋅107    = 22 kilotons of TNT
Fusion bomb                       =   4⋅1010   = 10 megatons of TNT
1 kg of antimatter                =   9⋅1010   = 20 megatons of TNT
Krakatoa volcano, 1883            =   8⋅1011
World energy production in 1 year =   6⋅1014
Dinosaur-extinction asteroid      =   5⋅1017
Typical energy of a supernova     =   1⋅1038
Intense gamma ray burst           =   1⋅1041
```

Power
```                         Watts

Human cell                 10-12
Laptop computer            10
Human brain                20
Incandescent Light bulb    60
Human at rest             100
1 horsepower              746
Strenuous exercise       1000
Maximum human power      1600
World power per person   2500
Tesla S Ludicrous      397000       532 horsepower
Wind turbine               1⋅106
Blue whale               2.5⋅106
Boeing 747               1.4⋅108
Hoover Dam               2.1⋅109
U.S. power consumption   3.4⋅1012
World power consumption  1.5⋅1013
Earth geologic heat      4.4⋅1013
World photosynthesis     7.5⋅1013
Hurricane                1.0⋅1014
Earth solar power        1.7⋅1017    Total solar power falling on the Earth
```

Temperature

```                        Kelvin   Celsius   Fahrenheit

Absolute zero             0      -273.2     -459.7
Water melting point     273.2       0         32
Room temperature        294        21         70
Human body temperature  310        37         98.6
Water boiling point     373.2     100        212

Kelvin

Absolute zero             0
Helium boiling point      4.2
Hydrogen boiling point   20.3
Triton                   38
Pluto                    44
Titania                  70
Nitrogen boiling point   77.4
Oxygen boiling point     90.2
Titan                    94
Europa                  102
Hottest superconductor  135          HgBaCaCuO
Ceres                   168
Mars                    210
Water melting point     273.15
Earth average           288
Room temperature        293
Water boiling point     373.15
Venus                   740
Wood fire              1170
Copper melting point   1358
Iron melting point     1811
Bunsen burner          1830
Tungsten melting point 3683          Highest melting point among metals
Earth's core           5650          Inner-core boundary
Sun's surface          5780
Solar core             13.6 million
Helium-4 fusion         200 million
Carbon-12 fusion        230 million
```

Pressure

```                 Pressure in bars

Air on Mars              .0063
Air at Everest           .30       10  km altitude
Air at Denver            .8        1.6 km altitude
Air at sea level        1.0        15 pounds per square inch
Air on Titan            1.46
Inside a football       1.9        15 + 13 pounds per square inch
10 meters underwater    2.0
Air on Venus           92.1
Seawolf nuclear sub    50          Maximum depth of 490 meters
11 km underwater     1100          Mariana trench, deepest part of the ocean
```
1 bar = 101300 Pascals
```              Energy density
(MegaJoules/kg)

Antimatter     90 billion
Hydrogen bomb  25,000,000    theoretical maximum yield
Hydrogen bomb  21,700,000    highest achieved yield
Uranium        20,000,000    nuclear fuel
Hydrogen              143
Natural gas            53.6
Gasoline               47
Jet fuel               43
Fat                    37
Coal                   24
Carbohydrates & sugar  17
Protein                16.8
Wood                   16
Lithium-air battery     9
TNT                     4.6
Gunpowder               3
Lithium battery         1.3
Lithium-ion battery      .72
Alkaline battery         .59
Compressed air           .5        300 atmospheres
Supercapacitor           .1
Capacitor                .00036
```
The energy cost to convert water to hydrogen and oxygen is 13.16 MJ/kg. If hydrogen and oxygen are reacted to produce one kg of water, the energy produced is equivalent to a 1 kg mass moving at 5.13 km/s.

Frequency

```                        Frequency   Note
(Hertz)

Whale songs                 10
Human ear lower limit       20
Bass lowest note            41       E
Bass guitar lowest note     41       E
Cello lowest note           65       C
Bass singer lowest note     82       E
Viola & tenor lowest note  131       C
Violin & alto lowest note  196       G
Soprano lowest note        262       C
Violin D string            293       D
Violin A string            440       A
Violin E string            660       E
Human ear upper limit    20000
```

Science fundamentals

Prefixes
```
terameter   =  Tm  =  10$12$  meters
gigameter   =  Bm  =  10$9$   meters
megameter   =  Mm  =  10$6$   meters
kilometer   =  km  =  10$3$   meters
meter       =   m  =  10$0$   meters
centimeter  =  cm  =  10$-2$  meters
millimeter  =  mm  =  10$-3$  meters
micrometer  =  μm  =  10$-6$  meters
nanometer   =  nm  =  10$-9$  meters
picometer   =  pm  =  10$-12$ meters
femtometer  =  fm  =  10$-15$ meters

1 million kg       =  1 Mkg
1 million dollars  =  1 M\$
```

Scientific notation

Examples of scientific notation.

```    1   = 100  =  e0
10   = 101  =  e1
100   = 102  =  e2
123   = 1.23⋅102  =  1.23e2
0.123   = 1.23⋅10-1  = 1.23e-1

11000 * .012  =  1.1⋅104 * 1.2⋅10-2  =  1.32⋅102  =  132
```
The abbreviation "e" for "10^" comes from Fortran and is standard in all programming languages.
Precision

A measurement consists of a quantity and an estimated error. For example, you might measure the length of a room to be

```Length  =  6.35 ± .02 meters
```
"6.35" is the measurement and ".02" is the estimated error.

Care should be taken to use an appropriate number of digits. For example,

```Length  =  6.3     ± .02 meters                   Not enough digits in the measured quantity
Length  =  6.34    ± .02 meters                   Minimum number of digits to state the measured quantity
Length  =  6.342   ± .02 meters                   It is wise to to include an extra digit
Length  =  6.3421  ± .02 meters                   Too many digits.  The last digit is unnecessary.
```
The fractional error is defined as
```Fractional error  =  Error  /  Measured quanitity
=   .02   /       6.34
=       .0032
```
Rounding:
```6.3424  →  6.342
6.3425  →  6.342
6.3426  →  6.343
```
If the last digit is even then round down, and if odd then round up. This prevents bias in rounding. For example:
```6.3405  →  6.340
6.3415  →  6.342
6.3425  →  6.342
6.3435  →  6.344
6.3445  →  6.344
```

Unit conversion
```1 mile  =  1609 meters
1 hour  =  3600 seconds

1609 meters        1 hour
1 mile/hour  =  1 mile/hour  *  -----------  *  ------------  =  .447 meters/second
1 mile        3600 seconds
```

SI units

If you have data that is not in SI units, then the safest procedure is to convert everything to SI units do the calculation. You can't go wrong with this. For example, if a car moving at 70 mph travels for 2 hours, how far does it go?

```Speed of a car     =  V          =   70 mph    =    31.3 meters/second
Time traveled      =  T          =    2 hours  =    7200 seconds
Distance traveled  =  X  =  V T  =  140 miles  =  225360 meters
```
One first converts 70 mph and 2 hours to SI units, then apply X=VT to arrive at X=225360 meters, and then convert this to mph.

Alternatively, you can do the calculation in non-SI units but care must be taken to make sure the units are consistent.

Logarithm

The logarithm is the inverse of the exponential function.

```                              log10 0   = -∞
10-2  =  .01                  log10 .01 = -2
10-1  =  .1                   log10 .1  = -1
100   =  1                    log10  1  =  0
101   =  10                   log10 10  =  1
102   =  100                  log10100  =  2

10log10x  =  log10 10x  =  x
eln x    =  ln ex      =  x

e-1     =   .368
e0      =  1
e1      =  2.718
e2      =  7.389
e3      = 20.086
```

2D tables of numbers

Many phenomena are besty understood by constructing a 2D table of numbers. For example, suppose you're wondering how to compare the alcohol content of a 6 pack of beer, a bottle of wine, and a bottle of Scotch. The following section constructs a table to show the alcohol content.

Alcohol

A typical bottle of beer has a volume of 12 ounces, is 5% alcohol, and contains
.6 ounces of alcohol. We use this amount as a reference unit and define
.6 ounces of alcohol to be one "Bond".

```Volume of the drink           =  V
Fraction of alcohol           =  F
Volume of alcohol             =  Valc   =  F V
Volume of one beer            =  Vbeer  =  12 ounces
Fraction of alcohol in beer   =  Fbeer  =  .05
Volume of alcohol in one beer =  VBond  =  .6 ounces
One ounce                     =  29.6 mL
One "Bond" of alcohol         =    .6 ounces
One wine or Scotch bottle     =  25.4 ounces  =  750 ml

Alcohol   Volume  Alcohol  Alcohol   \$    \$/Bond
fraction   (oz)    (oz)    (Bonds)

Beer (12 oz)      .05     12       .6       1       .67   .67   Budweiser
Wine glass        .13      4.6     .6       1      8     8.0    Napa Valley
Scotch shot       .40      1.5     .6       1      8     8.0    Laphroaig
Beer pitcher      .05     64      3.2       5.3   16     3.0    Budweiser
Beer keg          .05   1984     99.2     165.3  100      .60   Budweiser
Wine bottle       .13     25.4    3.3       5.5    3      .55   Charles Shaw
Vodka bottle      .40     25.4   10.1      16.9   15      .89   Smirnoff
Scotch bottle     .40     25.4   10.1      16.9   50     3.0    Laphroaig
Distilled ethanol .95     25.4   24.1      40.2   15      .37   Everclear
```

Physical constants
```Speed of light               2.9979e8   m/s
Gravitational constant       6.6738e-11 m3/kg/s2
Planck constant              6.6261e-34 J s
Earth surface gravity        9.8067     m/s
Electric force constant      8.9876e9   N m2 / C2
Magnetic constant            4 Pi e-7   N/A2
Proton mass                  1.6726e-27 kg  =  938.272 GeV
Neutron mass                 1.6749e-27 kg  =  939.565 GeV
Electron mass                9.1094e-31 kg
Electron charge              1.6022e-19 C
Atomic mass unit             1.6605e-27 kg
Bohr radius                  5.2918e-11 m           = hbar2 / (ElectronMass*ElectronCharge2*Ke)
Boltzmann constant           1.3806e-23 J/K
Gas constant                 8.3145     J/K/mole
Stefan-Boltzmann constant    5.6704e-8  Watts/m2/K4
Wein constant                2.8978e-3  m K
Mole of Carbon-12            .012       kg          Exact
Planck length                1.6162e-35 m
Planck mass                  2.1765e-8  kg
Planck time                  5.3911e-44 s
Planck charge                1.8755e-18 C
Planck temperature           1.4168e32  K
Water heat capacity          4200       J/kg/K
Steam heat capacity          2080       J/kg/K      At 100 Celsius
Ice heat capacity            2110       J/kg/K      At -10 Celsius
Air heat capacity            1004       J/kg/K
Stefan-Boltzmann             5.67e-8    Watts/meter2/Kelvin4
= (2π5/15) Boltzmann4 / SpeedOfLight2 / PlanckConstant3
Wein                         2.898e-3   Kelvin meters
Electron spin                5.2729e-35 Joule seconds  =  PlanckConstant / (4 Pi)

Pi                           3.14159
Euler number                 2.71828
```

Main page

Support the free online science textbooks project