AppendixDUnits of Measure¶ permalink
Unit | Stands For | Definition | Roughly |
m | meter | the distance light travels in \(\sfrac{1}{299792458}\) of a second |
half the height of a typical doorway |
mm | millimeter | exactly \(\sfrac{1}{1000}\) of a meter |
the thickness of a credit card |
cm | centimeter | exactly \(\sfrac{1}{100}\) of a meter |
the width of your pinky finger |
km | kilometer | exactly \(1000\) meters |
in parts of Portland where the city blocks are square, about \(12.5\) blocks |
in | inch | exactly \(0.0254\) meters |
diameter of a bottle cap |
ft | foot | exactly \(12\) inches |
the exterior length of an average adult male's shoe |
mi | mile | exactly \(5280\) feet |
in parts of Portland where the city blocks are square, about \(20\) blocks |
Unit | Stands For | Definition | Roughly |
cm2 | square centimeter | the area of a square whose sides are each one centimeter |
a little less than the circular area of a new pencil eraser |
in2 | square inch | the area of a square whose sides are each one inch |
the area of a photograph on an ID card |
Unit | Stands For | Definition | Roughly |
cm3 | cubic centimeter | the volume of a cube whose sides are each one centimeter |
the volume of a blueberry |
L | liter | exactly \(1000\) cubic centimeters |
a bottle of wine is \(\sfrac{3}{4}\) of a liter |
mL | milliliter | exactly \(1\) cubic centimeter; \(\sfrac{1}{1000}\) of a liter |
the volume of a blueberry |
in3 | cubic inch | the volume of a cube whose sides are each one inch |
the volume of an shelled whole walnut |
gal | liter | exactly \(231\) cubic inches |
the volume of the larger type of plastic milk containers sold in supermarkets |
Unit | Stands For | Definition | Roughly |
s | second | the duration of \(9192631770\) periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom |
the time it takes you to say the phrase “differential calculus” |
min | minute | exactly \(60\) seconds |
how long it takes to microwave a full dinner plate from the refrigerator |
h | hour | exactly \(3600\) seconds; exactly \(60\) minutes |
the length of one episode of a premium cable television show |
Unit | Stands For | Definition | Roughly |
mph | mile per hour | exactly one mile per hour |
a typical walking speed is about three miles per hour |
Unit | Stands For | Definition | Roughly |
kg | kilogram | the mass of a certain cylindrical object made of a platinum-iridium alloy called the International Prototype of the Kilogram, which is stored in Sèvres, France |
the mass of a \(500\)-page paperback book |
mg | milligram | exactly \(\sfrac{1}{1000000}\) of a kilogram |
the mass of a small snowflake |
Unit | Stands For | Definition | Roughly |
rad | radian | the angle subtended at the center of a circle by an arc that is equal in length to the radius of the circle |
a little less than the angles on an equilateral triangle |
° | degree | the angle subtended at the center of a circle by an arc whose length is \(\sfrac{1}{360}\) the circumference of the circle |
a very small angle; if you could look directly at the bottom of the sun, and then moved your eyes to look at the top of the sun, you would have moved your eyes about half of one degree |
Unit | Stands For | Definition | Roughly |
N | newton | the force needed to accelerate one kilogram from rest up to a speed of one meter per second with one second of time |
if you hold an apple in the palm of your hand, it applies about two newtons of force |
Unit | Stands For | Definition | Roughly |
kW | kilowatt | the power to transfer one thousand joules of energy in one second (one joule is the amount of energy used when one newton of force pushes an object one meter) |
the power used by a nicer microwave oven |