# Basics

## The SI-system, unit converters, physical constants, drawing scales and more

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### Acceleration Units Converter

Convert between units of acceleration

### Acceleration of Gravity and Newton's Second Law

Acceleration of gravity and Newton's Second Law - SI and Imperial units

### Air Properties

Density, specific heat, thermal conductivity, expansion coefficient, kinematic viscosity and Prandtl's number - air temperature ranging *-150 ^{ o}C to 400^{ o}C*

### Angle Converter

Convert between angle units

### British Imperial System

A principal system of units

### Circles - Circumferences and Areas

Area and circumferences of circles with diameters in inches

### Conversion Chart - from Inches to mm

Convert fractional and/or decimal inches to metric mm - and vice versa

### Convert Gallons of Water to Pounds

and vice versa

### Decimal System Prefixes

Prefix names of multiples and submultiples of units

### Density, Specific Weight and Specific Gravity

An introduction to density, specific weight and specific gravity - formulas with examples

### Drawing Scales

Commonly used scales for blueprint drawings

### Efficiency

Usefulnes of a process

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### Electromagnetic Spectrum

Electromagnetic wavelengths and frequencies

### Elements of the Periodic System

The elements of the periodic system with names, symbols, atomic numbers and weights, melting and boiling points, density, electronegativity and electron affinity, and electron configuration

### Empirical Equations

Empirical equations or formulas

### Equilibrium

Mechanical, thermal, electrostatic, phase and chemical equilibrium

### Exponents - Powers and Roots

Fractional and integer exponents laws

### Flow Units Converter

Convert between volume flow units - *gpm, liter/sec, cfm, m ^{3}/h* - an online flow unit calculator

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### Inches - Decimal Equivalents

Decimal equivalents of eights, sixteenths, thirty-seconds and sixty-fourths of an inch

### Inches - Fractions and Decimal Equivalents

Inches - fractional and decimal equivalents

### Inches to feet, yards and meters - Conversion Chart

Convert from inches to feet, yards and meters

### Length Units Converter

Convert between common length units like meters, feet, inches, nautical miles and more

### Logarithms

Rules of logarithms - log_{10} and log_{e} for numbers ranging 1 to 1000

### Mass and Weight

Mass and Weight - the Gravity Force

### Mixtures, Solutions and Suspensions

The difference between mixtures, solutions and suspensions

### Mole and Avagadro's Number

The mole is the SI base unit for amount of substance

### Moment of Inertia

Moment of Inertia (Mass Moment of Inertia) depends on the mass of the object, its shape and its relative point of rotation - Radius of Gyration

### Natural Trigonometric Functions

Sine, Cosine and Tangent - Natural Trigonometric Functions

### Online Fuel Equivalents Calculator

Online calculator to compute fuels energy equivalents - oil and gas

### Optical Distance Law

Distance and geometric dilution of light

### Ounces and Pounds converted to Grams

Converting ounces (*ozs.*) and pounds (*lbs.*) to grams (*g*)

### Parts per million - ppm

ppm - parts per million - commonly used as a unit of concentration

### Periodic Table of Elements

The periodic table of the elements with atomic numbers

### Physical Constants

Physical constants - SI Units

### Pressure

Introduction to pressure - *psi* and *Pa* - online pressure units converter

### Pressure Units - Online Converter

Convert between pressure units like *Pa, bar, atmosphere, pound square feet, psi and more*

### Pressure to Head Unit Converter

Convert between pressure and head units - *lb/in ^{2}, atm, inches mercury, bars, Pa and more ..*

### Properties and State

Concept of properties and state

### Pumps, Fans and Turbines - Horsepower

British Horse Power in pumps, fans and turbines - and how to convert to other units

### Radian

The radian - unit of angle measure - and angular velocity

### Ratio and Proportion

The relative values between quantities - ratio and proportion

### Real Numbers Algebra

Real numbers algebra - commutative law for addition, associative law for addition and more

### SI System

An introduction to the SI-system

### Solar System Constants

Sun, Earth and Moon constants

### Solids - Volumes and Surfaces

Volume and surface of solids like rectangular prism, cylinder, pyramid, cone and sphere - online calculator

### Some Measuring Units

Some commonly used measuring units - gross, dozen, quire, sheets ..

### Specific Heat - Online Converter

Online specific heat converter with the most commonly used units

### Temperature

Introduction to temperature - including Celsius, Fahrenheit, Kelvin and Rankine definitions - an online temperature converter

### U.S. Gallons to U.K. Gallons, Cubic Feet and Cubic Meters - Converting Chart

Convert between U.S. liquid Gallons, U.K. liquid Gallons, Cubic Feet and Cubic Meters

### USCS - United States Customary System Units

United States Customary System Units or Imperial Units

### Unit Converter with the most commonly used Units

Common converting units for Acceleration, Area, Density, Energy, Energy per unit mass, Force, Heat flow rate, Heat flux, Heat generation per unit volume and many more

### Vector Addition

Online vector calculator - add vectors with different magnitude and direction

### Velocity Units Converter

Convert between common velocity and speed units - online converter

### Volume Units Converter

Convert between common volume units like cubic meters, cubic feet, cubic inches and more

### Water Content in Food and other Products

Water content before and after drying in food and other products cork, grain, soap, peat, wood and more

### Water Pressure and Head

Pressure in pounds per square inch (psi) versus head in feet of water (ft_{h2o})

### pH Definition - basic (alkaline) and acidic

Introduction to pH - acidic and basic (alkaline)