Units of Measurement

Introduction

We live in a physical universe with physical matter, and a complete system of standardised units describing the physical quantities around us is required to allow us to measure and quantify the universe and its contents. Without a standard unit system, trade would be very difficult and science would be unable to build on previous results without using unwieldy fractions such as 1/47382 of a meter.

This book collects information on the units of measurement in use, defining them and comparing to other units in the same and other systems. For example, you may find a meter here, or a kilogram, or a nanosecond, or even a furlong.

Contents

Unit systems

• SI units
• CGS units
• Imperial units

Unit by physical quantity described

• Length
• Area
• Volume
• Mass
• Time
• Angle
• Frequency
• Temperature
• Density
• Velocity
• Angular velocity
• Acceleration
• Angular acceleration
• Force
• Pressure
• Energy
• Power
• Action
• Entropy
• Viscosity
• Surface tension
• Thermal conductivity
• Amount of substance
• vibration