The following tables list some common physical, mechanical, and electrical quantities, along with their units and the corresponding symbols.
General Physical Quantities: These quantities are widely used in physics, mechanical engineering, electrical engineering, and other fields.
Quantity | Symbol | Unit | Symbol for the Unit |
acceleration | a | meters per second per second | m/s2 |
angle | θ or φ | radian | rad |
degree | ° | ||
angular frequency | ω | radians per second | rad/sec |
energy | W | joule | J |
force | F | newton | N |
pound | lb | ||
mass | m | kilogram | kg |
period | T | second | s |
power | P | watt | W |
time | t | second | s |
velocity | v | meters per second | m/s |
miles per hour | mph |
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 |
newton meter | N·m | ||
distributed load | q | pounds per inch | lb/in |
newtons per meter | N/m | ||
elastic modulus (also called Young's modulus) | E | pounds per square inch | lb/in2 |
newtons per square meter | N/m2 | ||
flexural rigidity | EI | pound inches squared | lb·in2 |
newton meters squared | N·m2 | ||
normal stress |
|
pounds per square inch | lb/in2 |
newtons per square meter | N/m2 | ||
second moment of area | I | inches to the fourth | in4 |
meters to the fourth | m4 | ||
shear force | V | pound | lb |
newton | N | ||
shear stress |
|
pounds per square inch | lb/in2 |
newtons per square meter | N/m2 | ||
spring rate | k | newtons per meter | N/m |
tension | T | newton | N |
pound | lb | ||
weight | W | newton | N |
pound | lb |
Electrical Quantities: These quantities are used in circuit analysis and other areas studied by electrical engineers.
Quantity | Symbol | Unit | Symbol for the Unit |
capacitance | C | farad | F |
charge | Q | coulomb | C |
current | I | ampere | A |
impedance | Z | ohm | Ω |
inductance | L | henry | H |
reactance | X | ohm | Ω |
resistance | R | ohm | Ω |
voltage | V | volt | V |