Prefix

Symbol

Value

milli-

m

0.001

centi-

c

0.01

Kilo-

k

1000

Mega-

M

1,000,000

Quantity

Symbol

Unit

Unit’s symbol

Relationship

Displacement

l

meter

m, km, mm

# in, mile

# 1 in = 25.4 mm

# 1 mile = 1.609 km

Mass

m

kilogram

kg, t

1 ton = 1000 kg

Time

t

second

s, min, h

1 minute (min) = 60 s

1 hour (h) = 3,600 s

* Angular displacement

θ

rad

1 rad = 180/π  ^o

Area

A (l²)

m², cm², mm²

Volume

V (l³)

liter

cc  (cm³)

m³,  L, cc

# gal, in³

l L = 1000 cm³ (cc)

# 1 in³ = 16.3871 cc

           = 0.01639 L

# 1 Gallon (US) = 3.7854 L

# 1Gallon (UK) = 4.5461 L

Velocity

v (l/t)

m/s, km/h

# mile/h (mph)

1 m/s = 3.6 km/h

# 1 mile/h = 1.609 km/h

* Angular Velocity

ω

N

rad/s, rpm

ω = 2π N/60

Acceleration

+ a (l/t²)

m/s²

(km/h)/s    [car]

* Angular Acceleration

α

rad/s²

Force

F (m.a)

Newton

N, kN

1 N = 1 kg m/s²

Weight

w, G

Newton

N, kN

# lb

w = m.g = m x 9.81

# 1 lb = 4.44822 N

Pressure §

p (F/A)

Pascal

Pa, kPa, MPa

# psi

1 Pa = 1 N/m²

1 MPa = 1 N/mm²

# 1 psi = 6894.76 Pa

Torque

T (F.l)

N.m

# lb.ft

# 1 lb.ft = 1.356 N.m

Energy, Work

W (F.l)

Joule

J, kJ

#Btu

1 J = 1 N.m

1 J = 1 W.s

# 1 Btu = 1.05506 kJ

Power

P (W/t)

Watt

horsepower

W, kW

PS, #bhp

1 Watt = 1 N.m/s

           = 1 J/s

P = T.ω   [engine]

P = F.v    [car]

1 PS = 75 kg.m/s

# 1 bhp = 550 lb.ft/s

1 kW = 1.36 PS

#1 bhp = 1.0142 PS

#1 bhp = 0.7457 kW

Density

ρ (m/V)

kg/m³, kg/L
# lb/ft²

# 1 lb/ft³= 16.018 kg/m³

Fuel Consumption

kg/h, L/h

L/(100 km), km/L

# mile/gal  

    (mpg)

[engine]

[car]

# x  mile/gal (US)

=  x / 2.353  km/L

= (235.26/x)  L/100 km

# x  mile/gal (UK)

= x / 2.825 km/L

= (282.48/x)  L/100 km