# 0.4 1.5 physical quantities and units  (Page 4/17)

 Page 4 / 17

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:

$80\overline{)\text{m}}×\frac{\text{1 km}}{1000\overline{)\text{m}}}=0\text{.080 km.}$

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.

Click [link] for a more complete list of conversion factors.

Approximate values of length, mass, and time
Lengths in meters Masses in kilograms (more precise values in parentheses) Times in seconds (more precise values in parentheses)
${\text{10}}^{-\text{18}}$ Present experimental limit to smallest observable detail ${\text{10}}^{-\text{30}}$ Mass of an electron ${\text{10}}^{-\text{23}}$ Time for light to cross a proton
${\text{10}}^{-\text{15}}$ Diameter of a proton ${\text{10}}^{-\text{27}}$ Mass of a hydrogen atom ${\text{10}}^{-\text{22}}$ Mean life of an extremely unstable nucleus
${\text{10}}^{-\text{14}}$ Diameter of a uranium nucleus ${\text{10}}^{-\text{15}}$ Mass of a bacterium ${\text{10}}^{-\text{15}}$ Time for one oscillation of visible light
${\text{10}}^{-\text{10}}$ Diameter of a hydrogen atom ${\text{10}}^{-5}$ Mass of a mosquito ${\text{10}}^{-\text{13}}$ Time for one vibration of an atom in a solid
${\text{10}}^{-8}$ Thickness of membranes in cells of living organisms ${\text{10}}^{-2}$ Mass of a hummingbird ${\text{10}}^{-8}$ Time for one oscillation of an FM radio wave
${\text{10}}^{-6}$ Wavelength of visible light $\text{1}$ Mass of a liter of water (about a quart) ${\text{10}}^{-3}$ Duration of a nerve impulse
${\text{10}}^{-3}$ Size of a grain of sand ${\text{10}}^{2}$ Mass of a person $\text{1}$ Time for one heartbeat
$\text{1}$ Height of a 4-year-old child ${\text{10}}^{3}$ Mass of a car ${\text{10}}^{5}$ One day $\left(8\text{.}\text{64}×{\text{10}}^{4}\phantom{\rule{0.25em}{0ex}}\text{s}\right)$
${\text{10}}^{2}$ Length of a football field ${\text{10}}^{8}$ Mass of a large ship ${\text{10}}^{7}$ One year (y) $\left(3\text{.}\text{16}×{\text{10}}^{7}\phantom{\rule{0.25em}{0ex}}\text{s}\right)$
${\text{10}}^{4}$ Greatest ocean depth ${\text{10}}^{\text{12}}$ Mass of a large iceberg ${\text{10}}^{9}$ About half the life expectancy of a human
${\text{10}}^{7}$ Diameter of the Earth ${\text{10}}^{\text{15}}$ Mass of the nucleus of a comet ${\text{10}}^{\text{11}}$ Recorded history
${\text{10}}^{\text{11}}$ Distance from the Earth to the Sun ${\text{10}}^{\text{23}}$ Mass of the Moon ${\text{10}}^{\text{17}}$ Age of the Earth
${\text{10}}^{\text{16}}$ Distance traveled by light in 1 year (a light year) ${\text{10}}^{\text{25}}$ Mass of the Earth ${\text{10}}^{\text{18}}$ Age of the universe
${\text{10}}^{\text{21}}$ Diameter of the Milky Way galaxy ${\text{10}}^{\text{30}}$ Mass of the Sun
${\text{10}}^{\text{22}}$ Distance from the Earth to the nearest large galaxy (Andromeda) ${\text{10}}^{\text{42}}$ Mass of the Milky Way galaxy (current upper limit)
${\text{10}}^{\text{26}}$ Distance from the Earth to the edges of the known universe ${\text{10}}^{\text{53}}$ Mass of the known universe (current upper limit)

## Unit conversions: a short drive home

Suppose that you drive the 10.0 km from your university to home in 20.0 min. Calculate your average speed (a) in kilometers per hour (km/h) and (b) in meters per second (m/s). (Note: Average speed is distance traveled divided by time of travel.)

anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
how did you get the value of 2000N.What calculations are needed to arrive at it
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!