# Physical Quantities + Units

- Created by: Jane
- Created on: 07-04-13 20:47

First 200 words of the document:

Physical Quantities + Units:

There are 7 base quantities with 7 base units

Base Quantity Symbol Base Unit Symbol

time t second s

length l metre m

mass m kilogram kg

temperature T, kelvin K

electric current I ampere A

amount of substance n mole mol

(luminous intensity) - candela cd

Derived Units:

All physical quantities that aren't measured in the 7 base units are known as derived quantities. The quantity and its

unit are derived from a combination of base units using a defining equation.

Example:

Both distance and length are base quantities and metres and seconds are base units so the derived unit of velocity is

metres per second written m/s or m s-1

The derived unit of acceleration is metres per second per second or metres per second squared written m/s2 or m

s-2

Common Derived Units:

Physical Quantity Defined As Unit Special Name

density

momentum

)

force newton (N)

)

pressure pascal (Pa)

work (energy) joule (J)

power watt (W)

electrical charge coulomb (C)

potential difference volt (V)

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