Table of Quantities and Units

The following tables list some common physical, mechanical, and electrical quantities, along with their units and the corresponding symbols.

In cases where a quantity has two or more commonly used units (such as force, which can have units of either newtons or pounds), these units and their symbols are listed on separate lines.
Note that the same symbol may be used for more than one quantity, in which case the context will make clear which quantity is intended. For example, T can be used to represent either period or tension.

General Physical Quantities: These quantities are widely used in physics, mechanical engineering, electrical engineering, and other fields.

Mechanical Quantities: These quantities are used in statics, dynamics, strength of materials, and other areas studied by mechanical engineers.

Quantity	Symbol	Unit	Symbol for the Unit
bending moment	M	pound inch	lb·in
bending moment	M	newton meter	N·m
distributed load	q	pounds per inch	lb/in
distributed load	q	newtons per meter	N/m
elastic modulus (also called Young's modulus)	E	pounds per square inch	lb/in²
elastic modulus (also called Young's modulus)	E	newtons per square meter	N/m²
flexural rigidity	EI	pound inches squared	lb·in²
flexural rigidity	EI	newton meters squared	N·m²
normal stress	σ	pounds per square inch	lb/in²
normal stress	σ	newtons per square meter	N/m²
second moment of area	I	inches to the fourth	in⁴
second moment of area	I	meters to the fourth	m⁴
shear force	V	pound	lb
shear force	V	newton	N
shear stress	τ	pounds per square inch	lb/in²
shear stress	τ	newtons per square meter	N/m²
spring rate	k	newtons per meter	N/m
tension	T	newton	N
tension	T	pound	lb
weight	W	newton	N
weight	W	pound	lb

Electrical Quantities: These quantities are used in circuit analysis and other areas studied by electrical engineers.