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1.2 Physical quantities and units  (Page 5/18)

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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)
10 − 18 Present experimental limit to smallest observable detail 10 − 30 size 12{"10" rSup { size 8{ - "30"} } } {} Mass of an electron 9 . 11 × 10 − 31  kg size 12{9 "." "11" times "10" rSup { size 8{ - "31"} } `"kg"} {} 10 − 23 size 12{"10" rSup { size 8{ - "23"} } } {} Time for light to cross a proton
10 − 15 size 12{"10" rSup { size 8{ - "15"} } } {} Diameter of a proton 10 − 27 size 12{"10" rSup { size 8{ - "27"} } } {} Mass of a hydrogen atom 1 . 67 × 10 − 27  kg size 12{1 "." "67" times "10" rSup { size 8{ - "27"} } `"kg"} {} 10 − 22 size 12{"10" rSup { size 8{ - "22"} } } {} Mean life of an extremely unstable nucleus
10 − 14 size 12{"10" rSup { size 8{ - "14"} } } {} Diameter of a uranium nucleus 10 − 15 size 12{"10" rSup { size 8{ - "15"} } } {} Mass of a bacterium 10 − 15 size 12{"10" rSup { size 8{ - "15"} } } {} Time for one oscillation of visible light
10 − 10 size 12{"10" rSup { size 8{ - "10"} } } {} Diameter of a hydrogen atom 10 − 5 size 12{"10" rSup { size 8{ - 5} } } {} Mass of a mosquito 10 − 13 size 12{"10" rSup { size 8{ - "13"} } } {} Time for one vibration of an atom in a solid
10 − 8 size 12{"10" rSup { size 8{ - 8} } } {} Thickness of membranes in cells of living organisms 10 − 2 size 12{"10" rSup { size 8{ - 2} } } {} Mass of a hummingbird 10 − 8 size 12{"10" rSup { size 8{ - 8} } } {} Time for one oscillation of an FM radio wave
10 − 6 size 12{"10" rSup { size 8{ - 6} } } {} Wavelength of visible light 1 size 12{"1"} {} Mass of a liter of water (about a quart) 10 − 3 size 12{"10" rSup { size 8{ - 3} } } {} Duration of a nerve impulse
10 − 3 size 12{"10" rSup { size 8{ - 3} } } {} Size of a grain of sand 10 2 size 12{"10" rSup { size 8{2} } } {} Mass of a person 1 size 12{"1"} {} Time for one heartbeat
1 size 12{"1"} {} Height of a 4-year-old child 10 3 size 12{"10" rSup { size 8{3} } } {} Mass of a car 10 5 size 12{"10" rSup { size 8{5} } } {} One day 8 . 64 × 10 4 s size 12{8 "." "64" times "10" rSup { size 8{4} } `s} {}
10 2 size 12{"10" rSup { size 8{2} } } {} Length of a football field 10 8 size 12{"10" rSup { size 8{8} } } {} Mass of a large ship 10 7 size 12{"10" rSup { size 8{7} } } {} One year (y) 3 . 16 × 10 7 s size 12{3 "." "16" times "10" rSup { size 8{7} } `s} {}
10 4 size 12{"10" rSup { size 8{4} } } {} Greatest ocean depth 10 12 size 12{"10" rSup { size 8{"12"} } } {} Mass of a large iceberg 10 9 size 12{"10" rSup { size 8{9} } } {} About half the life expectancy of a human
10 7 size 12{"10" rSup { size 8{7} } } {} Diameter of the Earth 10 15 size 12{"10" rSup { size 8{"15"} } } {} Mass of the nucleus of a comet 10 11 size 12{"10" rSup { size 8{"11"} } } {} Recorded history
10 11 size 12{"10" rSup { size 8{"11"} } } {} Distance from the Earth to the Sun 10 23 size 12{"10" rSup { size 8{"23"} } } {} Mass of the Moon 7 . 35 × 10 22  kg size 12{7 "." "35" times "10" rSup { size 8{"22"} } `"kg"} {} 10 17 size 12{"10" rSup { size 8{"17"} } } {} Age of the Earth
10 16 size 12{"10" rSup { size 8{"16"} } } {} Distance traveled by light in 1 year (a light year) 10 25 size 12{"10" rSup { size 8{"25"} } } {} Mass of the Earth 5 . 97 × 10 24  kg size 12{5 "." "97" times "10" rSup { size 8{"24"} } `"kg"} {} 10 18 size 12{"10" rSup { size 8{"18"} } } {} Age of the universe
10 21 size 12{"10" rSup { size 8{"21"} } } {} Diameter of the Milky Way galaxy 10 30 size 12{"10" rSup { size 8{"30"} } } {} Mass of the Sun 1 . 99 × 10 30  kg size 12{1 "." "99" times "10" rSup { size 8{"30"} } `"kg"} {}
10 22 size 12{"10" rSup { size 8{"22"} } } {} Distance from the Earth to the nearest large galaxy (Andromeda) 10 42 size 12{"10" rSup { size 8{"42"} } } {} Mass of the Milky Way galaxy (current upper limit)
10 26 size 12{"10" rSup { size 8{"26"} } } {} Distance from the Earth to the edges of the known universe 10 53 size 12{"10" rSup { size 8{"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.)

Strategy

First we calculate the average speed using the given units. Then we can get the average speed into the desired units by picking the correct conversion factor and multiplying by it. The correct conversion factor is the one that cancels the unwanted unit and leaves the desired unit in its place.

Solution for (a)

(1) Calculate average speed. Average speed is distance traveled divided by time of travel. (Take this definition as a given for now—average speed and other motion concepts will be covered in a later module.) In equation form,

average speed = distance time . size 12{"average speed = " { {"distance"} over {"time"} } } {}

(2) Substitute the given values for distance and time.

average speed = 10 . 0  km 20 . 0  min = 0 . 500  km  min . size 12{"average speed = " { {"10" "." 0" km"} over {"20" "." 0" min"} } =0 "." "500" { {"km"} over {"min"} } } {}

(3) Convert km/min to km/h: multiply by the conversion factor that will cancel minutes and leave hours. That conversion factor is 60 min/hr size 12{"60 min/hr"}{} . Thus,

average speed = 0 . 500  km  min × 60  min 1  h = 30 . 0  km  h . size 12{"average speed = "0 "." "500" { {"km"} over {"min"} } times { {"60"" min"} over {1" h"} } ="30" "." 0 { {"km"} over {h} } } {}

Discussion for (a)

Questions & Answers

how does Neisseria cause meningitis
Nyibol Reply
what is microbiologist
Muhammad Reply
what is errata
Muhammad
is the branch of biology that deals with the study of microorganisms.
Ntefuni Reply
What is microbiology
Mercy Reply
studies of microbes
Louisiaste
when we takee the specimen which lumbar,spin,
Ziyad Reply
How bacteria create energy to survive?
Muhamad Reply
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Muhamad
they make spores
Louisiaste
what is sporadic nd endemic, epidemic
Aminu Reply
the significance of food webs for disease transmission
Abreham
food webs brings about an infection as an individual depends on number of diseased foods or carriers dully.
Mark
explain assimilatory nitrate reduction
Esinniobiwa Reply
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
Elkana
Examples of thermophilic organisms
Shu Reply
Give Examples of thermophilic organisms
Shu
advantages of normal Flora to the host
Micheal Reply
Prevent foreign microbes to the host
Abubakar
they provide healthier benefits to their hosts
ayesha
They are friends to host only when Host immune system is strong and become enemies when the host immune system is weakened . very bad relationship!
Mark
what is cell
faisal Reply
cell is the smallest unit of life
Fauziya
cell is the smallest unit of life
Akanni
ok
Innocent
cell is the structural and functional unit of life
Hasan
is the fundamental units of Life
Musa
what are emergency diseases
Micheal Reply
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life
Lubega
Heyy Lubega hussein where are u from?
_Adnan
en français
Adama
which site have a normal flora
ESTHER Reply
Many sites of the body have it Skin Nasal cavity Oral cavity Gastro intestinal tract
Safaa
skin
Asiina
skin,Oral,Nasal,GIt
Sadik
How can Commensal can Bacteria change into pathogen?
Sadik
How can Commensal Bacteria change into pathogen?
Sadik
all
Tesfaye
by fussion
Asiina
what are the advantages of normal Flora to the host
Micheal
what are the ways of control and prevention of nosocomial infection in the hospital
Micheal
what is inflammation
Shelly Reply
part of a tissue or an organ being wounded or bruised.
Wilfred
what term is used to name and classify microorganisms?
Micheal Reply
Binomial nomenclature
adeolu
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Source:  OpenStax, College physics for ap® courses. OpenStax CNX. Nov 04, 2016 Download for free at https://legacy.cnx.org/content/col11844/1.14
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