Approximate Metric Conversion Factors For Common Conversions

• Length
• Area
• Mass (Weight)
• Volume
• Temperature
• Mechanics
• Energy
• Light
• Electricity
• Tubing Related Formulae
• French Catheter Scale
• Needle Gauge Scale

	When You Know	Multiply by	To Find
	Length
	inches	25.4	millimeters
	inches	2.54	centimeters
	feet	30	centimeters
	millimeters	0.04	inches
	centimeters	0.4	inches
	meter	3.3	feet
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	Area
	square inches	6.5	square centimeters
	square feet	0.09	square meters
	square centimeters	0.16	square inches
	square meters	1.2	square yards
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	Mass (weight)
	ounces	28	grams
	pounds	0.45	kilograms
	grams	0.035	ounces
	kilograms	2.2	pounds
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	Volume
	pints	0.47	liters
	quarts	0.95	liters
	gallons	3.8	liters
	cubic feet	0.03	cubic meters
	cubic yards	0.76	cubic meters
	milliliters	0.03	fluid ounces
	liters	2.1	pints
	liters	1.06	quarts
	liters	0.26	gallons
	cubic meters	35	cubic feet
	cubic meters	1.3	cubic yards
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	Temperature
	Fahrenheit	5/9 (after subtracting 32)	Celsius
	Celsius	9/5 (then add 32)	Fahrenheit

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Formulae

Mechanics

Coefficient of Friction

m = coefficient of friction
F = force of friction
N = force normal to surface

Velocity

V_av = average velocity
d = distance travelled
t = elapsed time

Acceleration

a = acceleration
V_f = final velocity
V_i = initial velocity
t = elapsed time

Newton's 2nd Law of Motion

F = force
m = mass
a = acceleration

Law of Universal Gravitation

F = force of attraction
G = gravitational constant
m₁•m₂ = product of masses
d = distance between their centers

Centripetal Force

F = centripetal force
m = mass
v = velocity
r = radius of path

Pendulum

T = period
l = length
g = acceleration of gravity

Work

W = work
F = force
d = distance

Mechanical Advantage

IMA = ideal mechanical advantage
F_E = effort force
F_R = resistance force
AMA = actual mechanical advantage
d = distance

Mechanical Equivalent of Heat

W = work
J = mechanical equivalent of heat
Q = heat

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Energy

Kinetic Energy

K.E. = kinetic energy
m = mass
v = velocity

Potential Energy

P.E. = potential energy
m = mass
g = acceleration of gravity
h = vertical distance (height)

Relationship between Mass and Energy

E = energy
m = mass
e = velocity of light

Light

Wave Formula

v = wave speed
f = frequency
l = wave length

Uniformly Illuminated Surface

E = illumination
Y = luminous flux
A = uniformly illuminated area

Images in Mirrors and Lenses

S_o = object size
S_i = image size
D_o = object distance
D_i = image distance

Focal Length of Mirrors and Lenses

f = focal length
D_q = object distance
D_i = image distance

Index of Refraction

n = index of refraction
q_i = angle of incidence
q_r = angle of refraction

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Electricity

Electric Current

l = current
q = quantity of charge
t = time

Coulomb's Law of Electrostatics

F = force between two charges
k = proportionality constant
q₁•q₂ = product of charges
d = distance separating charges

Capacitance of a Capacitor

C = capacitance of a capacitor
V = potential difference between plates
q = charge on either plate

Ohm's Law of Resistance

E = emf of source
R = resistance of the circuit
l = current in the circuit

Joule's Law

H = heat energy
l = current
R = resistance
t = time

Faraday's Law of Electrolysis

m = mass
l = current
z = electrochemical equivalent
t = time

Induced emf: Coil in a Magnetic Field

E = induced emf
N = number of turns
D_F/D_t = the change in flux linkage in a given interval of time

Induced emf: Conductor in a Magnetic Field

E = induced emf
l = length of conductor
v = velocity of conductor across magnetic field
B = flux density of the magnetic field

Instantaneous Voltage

e = instantaneous voltage
E_max = maximum voltage
q = displacement angle

Instantaneous Current

i = instantaneous current
I_max = maximum current
q = displacement angle

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Tubing Related Formulae

Burst Pressure (P) in lbs/sq. in.

T = wall thickness in inches
S = material tensile strength in P.S.I.
O = outside diameter in inches

Operating Pressure (O.P.)


Ovality


Concentricity
Concentricity % = min. wall / max. wall • 100
Concentricity value = (max. wall - min. wall) • concentricity %

Specific Gravity (S.G.)

S.G. = specific gravity
m = mass
v = volume

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French Catheter Scale

	French Size	Inch Equivalent	mm Equivalent
	3F	0.039	1.0
	4F	0.053	1.35
	5F	0.066	1.67
	6F	0.079	2.0
	7F	0.092	2.3
	8F	0.105	2.7
	9F	0.118	3.0
	10F	0.131	3.3
	11F	0.144	3.7
	12F	0.158	4.0
	13F	0.170	4.3
	14F	0.184	4.7
	15F	0.197	5.0
	16F	0.210	5.3
	17F	0.223	5.7
	18F	0.236	6.0
	19F	0.249	6.3
	20F	0.263	6.7
	22F	0.288	7.3
	24F	0.315	8.0
	26F	0.341	8.7
	28F	0.367	9.3
	30F	0.393	10.0
	32F	0.419	10.7
	34F	0.445	11.3

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Needle Gauge Scale

	Gauge Size	Inch Equivalent	mm Equivalent
	13	0.095	2.413
	14	0.083	2.108
	15	0.072	1.829
	16	0.065	1.651
	17	0.058	1.473
	18	0.049	1.245
	19	0.042	1.067
	20	0.035	0.889
	21	0.032	0.813
	22	0.028	0.711
	23	0.025	0.635
	24	0.022	0.559
	25	0.020	0.508
	26	0.018	0.457
	27	0.016	0.406