1. Home
  2. College physics
  3. Introduction: the nature of
  4. Physical quantities and units

1.2 Physical quantities and units  (Page 4/18)

<< Chapter < Page
  College physics     Page 4 / 18
Chapter >> Page >
Metric prefixes for powers of 10 and their symbols
Prefix Symbol Value See Appendix A for a discussion of powers of 10. Example (some are approximate)
exa E 10 18 size 12{"10" rSup { size 8{"18"} } } {} exameter Em 10 18  m size 12{"10" rSup { size 8{"18"} } " m"} {} distance light travels in a century
peta P 10 15 size 12{"10" rSup { size 8{"15"} } } {} petasecond Ps 10 15  s size 12{"10" rSup { size 8{"15"} } " s"} {} 30 million years
tera T 10 12 size 12{"10" rSup { size 8{"12"} } } {} terawatt TW 10 12  W size 12{"10" rSup { size 8{"12"} } `W} {} powerful laser output
giga G 10 9 size 12{"10" rSup { size 8{9} } } {} gigahertz GHz 10 9  Hz size 12{"10" rSup { size 8{9} } `"Hz"} {} a microwave frequency
mega M 10 6 size 12{"10" rSup { size 8{6} } } {} megacurie MCi 10 6  Ci size 12{"10" rSup { size 8{6} } `"Ci"} {} high radioactivity
kilo k 10 3 size 12{"10" rSup { size 8{3} } } {} kilometer km 10 3  m size 12{"10" rSup { size 8{3} } " m"} {} about 6/10 mile
hecto h 10 2 size 12{"10" rSup { size 8{2} } } {} hectoliter hL 10 2  L size 12{"10" rSup { size 8{2} } " L"} {} 26 gallons
deka da 10 1 size 12{"10" rSup { size 8{1} } } {} dekagram dag 10 1  g size 12{"10" rSup { size 8{1} } `g} {} teaspoon of butter
— — 10 0 size 12{"10" rSup { size 8{0} } } {} (=1)
deci d 10 − 1 size 12{"10" rSup { size 8{ - 1} } } {} deciliter dL 10 − 1  L size 12{"10" rSup { size 8{ - 1} } `L} {} less than half a soda
centi c 10 − 2 size 12{"10" rSup { size 8{ - 2} } } {} centimeter cm 10 − 2  m size 12{"10" rSup { size 8{ - 2} } `m} {} fingertip thickness
milli m 10 − 3 size 12{"10" rSup { size 8{ - 3} } } {} millimeter mm 10 − 3  m size 12{"10" rSup { size 8{ - 3} } `m} {} flea at its shoulders
micro µ 10 − 6 size 12{"10" rSup { size 8{ - 6} } } {} micrometer µm 10 − 6  m size 12{"10" rSup { size 8{ - 6} } `m} {} detail in microscope
nano n 10 − 9 size 12{"10" rSup { size 8{ - 9} } } {} nanogram ng 10 − 9  g size 12{"10" rSup { size 8{ - 9} } `g} {} small speck of dust
pico p 10 − 12 size 12{"10" rSup { size 8{ - "12"} } } {} picofarad pF 10 − 12  F size 12{"10" rSup { size 8{ - "12"} } F} {} small capacitor in radio
femto f 10 − 15 size 12{"10" rSup { size 8{ - "15"} } } {} femtometer fm 10 − 15  m size 12{"10" rSup { size 8{ - "15"} } `m} {} size of a proton
atto a 10 − 18 size 12{"10" rSup { size 8{ - "18"} } } {} attosecond as 10 − 18  s size 12{"10" rSup { size 8{ - "18"} } `s} {} time light crosses an atom

Known ranges of length, mass, and time

The vastness of the universe and the breadth over which physics applies are illustrated by the wide range of examples of known lengths, masses, and times in [link] . Examination of this table will give you some feeling for the range of possible topics and numerical values. (See [link] and [link] .)

A magnified image of tiny phytoplankton swimming among the crystal of ice.[
Tiny phytoplankton swims among crystals of ice in the Antarctic Sea. They range from a few micrometers to as much as 2 millimeters in length. (credit: Prof. Gordon T. Taylor, Stony Brook University; NOAA Corps Collections)
A view of Abell Galaxy with some bright stars and some hot gases.
Galaxies collide 2.4 billion light years away from Earth. The tremendous range of observable phenomena in nature challenges the imagination. (credit: NASA/CXC/UVic./A. Mahdavi et al. Optical/lensing: CFHT/UVic./H. Hoekstra et al.)

Unit conversion and dimensional analysis

It is often necessary to convert from one type of unit to another. For example, if you are reading a European cookbook, some quantities may be expressed in units of liters and you need to convert them to cups. Or, perhaps you are reading walking directions from one location to another and you are interested in how many miles you will be walking. In this case, you will need to convert units of feet to miles.

Let us consider a simple example of how to convert units. Let us say that we want to convert 80 meters (m) to kilometers (km).

The first thing to do is to list the units that you have and the units that you want to convert to. In this case, we have units in meters and we want to convert to kilometers .

Next, we need to determine a conversion factor    relating meters to kilometers. A conversion factor is a ratio expressing how many of one unit are equal to another unit. For example, there are 12 inches in 1 foot, 100 centimeters in 1 meter, 60 seconds in 1 minute, and so on. In this case, we know that there are 1,000 meters in 1 kilometer.

Now we can set up our unit conversion. We will write the units that we have and then multiply them by the conversion factor so that the units cancel out, as shown:

80 m × 1 km 1000 m = 0 .080 km. size 12{"80"" m" times { {"1 km"} over {"1000 m"} } =0 "." "080"`"km"} {}

Note that the unwanted m unit cancels, leaving only the desired km unit. You can use this method to convert between any types of unit.

Questions & Answers

material that allows electric current to pass through
Deng Reply
material which don't allow electric current is called
Deng
insulators
Covenant
how to study physic and understand
Ewa Reply
what is conservative force with examples
Moses
what is work
Fredrick Reply
the transfer of energy by a force that causes an object to be displaced; the product of the component of the force in the direction of the displacement and the magnitude of the displacement
AI-Robot
why is it from light to gravity
Esther Reply
difference between model and theory
Esther
Is the ship moving at a constant velocity?
Kamogelo Reply
The full note of modern physics
aluet Reply
introduction to applications of nuclear physics
aluet Reply
the explanation is not in full details
Moses Reply
I need more explanation or all about kinematics
Moses
yes
zephaniah
I need more explanation or all about nuclear physics
aluet
Show that the equal masses particles emarge from collision at right angle by making explicit used of fact that momentum is a vector quantity
Muhammad Reply
yh
Isaac
A wave is described by the function D(x,t)=(1.6cm) sin[(1.2cm^-1(x+6.8cm/st] what are:a.Amplitude b. wavelength c. wave number d. frequency e. period f. velocity of speed.
Majok Reply
what is frontier of physics
Somto Reply
A body is projected upward at an angle 45° 18minutes with the horizontal with an initial speed of 40km per second. In hoe many seconds will the body reach the ground then how far from the point of projection will it strike. At what angle will the horizontal will strike
Gufraan Reply
Suppose hydrogen and oxygen are diffusing through air. A small amount of each is released simultaneously. How much time passes before the hydrogen is 1.00 s ahead of the oxygen? Such differences in arrival times are used as an analytical tool in gas chromatography.
Ezekiel Reply
please explain
Samuel
what's the definition of physics
Mobolaji Reply
what is physics
Nangun Reply
the science concerned with describing the interactions of energy, matter, space, and time; it is especially interested in what fundamental mechanisms underlie every phenomenon
AI-Robot
<< Chapter < Page Page > Chapter >>
Practice Key Terms 12

Read also:

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now
Start Quiz
Learn




Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'College physics' conversation and receive update notifications?

Ask