Systems

Units on SI and ISO standards handbook 2.1979

Units based on the foot, pound and others; definitions and conversion factors, further abbreviations. examples

Quantity

Name of unit

Internal symbol

Time

t

Second

Minute

Hour

day

s

min

h

d

Time: T; year(s): yr(s);

day(s): dy(dys); hour(s): hr(s);

minute(s): min(s)='

second(s): sec(s)="; e.g. 4'30"

Length

l

Metre

nautical mile

M

n mile

inch: 1 in=25.4 mm (abbr.: i, in(s))

foot: 1 ft =12 in =0.3048 m e.g. 13'3" = 13 ft 3 in

yard: 1 yd=3 ft=36 in=0.9144 m mile: 1

mile=5280 ft= 1609.344 m (abbr.: m, ml(s))

Area

A

square metre

m²

square inch: in² (sq in)

square foot: ft² (sq ft)

square yard: yd² (sq yd)

square mile: mile² (sq ml) 1 acre =4840 yd²

Volume

V

cubic metre litre

m³

cubic inch: in^cu.in)

cubic foot: ft³ (cu.ft)

cubic yard: yd³ (cu.yd)

UK: gallon: 1 gal =277.42 in3 = 4.54609 dm³ pint: 8pt=1 gal;

fluid ounce: 160 fl oz=1 gal bushel: 1

bushel =8 gal

US: gallon: 1 gal =231 in³ =0.832674 gal (UK) =3.78541 dm³ liquid pint: 8

liq pt=1 gal;

fluid ounce: 128 fl oz=1 gal

barrel: 1 barrel =42 gal (for petroleum) bushel: 1 bu= 2150.42 cu.in;

dry pint: 64 dry pt=1 bu

dry barrel: 1 bbl=7056 тэ= 115.627 dm³ (dry)

Velocity

u,w

v,c

metre per second

kilometre per hour knot

m/s

km/h kn

foot per second: 1 ft/s= 0.3048 m/s

mile per hour: 1 mile/h= 0.44704 m/s 1 km/h =1/3.6 m/s =0.277778 m/s

1 kn=1 n mile per hour =0.514444 m/s

Acceleration

a

metre per second squared

m/s²

foot per second squared: 1 m/s²= 0.3048 m/s²

Frequency

f,v

hertz

Hz

Mass

m

kilogram

tonne

kg t

pound: 1 lb= 0.453592237 kg;

grain: 7000 gr=1 Ib

ounce: 1 oz=1/16 lb= 28.349 g;

1 troy ounce =480 gr stone: 1 st=14 Ib (weight); hundredweight: 1 cwt=112 Ib

metric ton (UK) = 1000 kg

Force

F

newton

N

1 N is that force which, when applied to a body having a mass of 1 kg, gives it an acceleration of 1 m/s². pound force: 1 lbf= 4.44822 N

Pressure

P

Pascal

bar

Pa

bar

1 Pa=1 N/m²; 1 bar^O-'Pa pound force per square inch:

1 Ibf/in²^ 684.76 Pa

Work, Energy

W,E

Joule

watt hour

J

Wh

1 J=1 Nm=1Ws; 1 Wh=3.6x10³J

1 Kwh=3.6 MJ (megajoule)

foot pound-force: 1 ft lbf= 1.35582 J

Power

P

Watt

W

1W=1 J/s = V x A

foot pound-force per second:

1 ft ibf/s = 1.35582W

horsepower: 1hp = 550 ft lbf/s = 745.7W

Heat

Q

Joule

J

British thermal unit:

1Btu = 778.169 ft lbf = 1056.06 J

Temperature

T

Degree

Celsius

C

K

Degree Fahrenheit: 1 F = 9/5 tC +32

e.g. 32F = 0C: thirty two degrees

Fahrenheit equals zero (nought)

Degrees centigrade

Electric current

L

Ampere

A

Ampere(s): amp(s)

Electromotive force

E

Volt

V

e.g. 24V = twenty four volts

Resistance

R

Ohm

Ω

1 Ω = 1 V / A