<P> The derived units in the SI are formed by powers, products or quotients of the base units and are unlimited in number . Derived units are associated with derived quantities; for example, velocity is a quantity that is derived from the base quantities of time and length, and thus the SI derived unit is metre per second (symbol m / s). The dimensions of derived units can be expressed in terms of the dimensions of the base units . </P> <P> Combinations of base and derived units may be used to express other derived units . For example, the SI unit of force is the newton (N), the SI unit of pressure is the pascal (Pa)--and the pascal can be defined as one newton per square metre (N / m). </P> <Table> Named SI derived units <Tr> <Th> Name </Th> <Th> Symbol </Th> <Th> Quantity </Th> <Th> In other SI units </Th> <Th> In SI base units </Th> </Tr> <Tr> <Td> radian </Td> <Td> rad </Td> <Td> angle </Td> <Td> </Td> <Td> (m ⋅ m) </Td> </Tr> <Tr> <Td> steradian </Td> <Td> sr </Td> <Td> solid angle </Td> <Td> </Td> <Td> (m ⋅ m) </Td> </Tr> <Tr> <Td> hertz </Td> <Td> Hz </Td> <Td> frequency </Td> <Td> </Td> <Td> s </Td> </Tr> <Tr> <Td> newton </Td> <Td> </Td> <Td> force, weight </Td> <Td> </Td> <Td> kg ⋅ m ⋅ s </Td> </Tr> <Tr> <Td> pascal </Td> <Td> Pa </Td> <Td> pressure, stress </Td> <Td> N / m </Td> <Td> kg ⋅ m ⋅ s </Td> </Tr> <Tr> <Td> joule </Td> <Td> J </Td> <Td> energy, work, heat </Td> <Td> N ⋅ m = Pa ⋅ m </Td> <Td> kg ⋅ m ⋅ s </Td> </Tr> <Tr> <Td> watt </Td> <Td> </Td> <Td> power, radiant flux </Td> <Td> J / s </Td> <Td> kg ⋅ m ⋅ s </Td> </Tr> <Tr> <Td> coulomb </Td> <Td> </Td> <Td> electric charge or quantity of electricity </Td> <Td> </Td> <Td> s ⋅ A </Td> </Tr> <Tr> <Td> volt </Td> <Td> V </Td> <Td> voltage (electrical potential), emf </Td> <Td> W / A </Td> <Td> kg ⋅ m ⋅ s ⋅ A </Td> </Tr> <Tr> <Td> farad </Td> <Td> </Td> <Td> capacitance </Td> <Td> C / V </Td> <Td> kg ⋅ m ⋅ s ⋅ A </Td> </Tr> <Tr> <Td> ohm </Td> <Td> Ω </Td> <Td> resistance, impedance, reactance </Td> <Td> V / A </Td> <Td> kg ⋅ m ⋅ s ⋅ A </Td> </Tr> <Tr> <Td> siemens </Td> <Td> </Td> <Td> electrical conductance </Td> <Td> Ω </Td> <Td> kg ⋅ m ⋅ s ⋅ A </Td> </Tr> <Tr> <Td> weber </Td> <Td> Wb </Td> <Td> magnetic flux </Td> <Td> V ⋅ s </Td> <Td> kg ⋅ m ⋅ s ⋅ A </Td> </Tr> <Tr> <Td> tesla </Td> <Td> </Td> <Td> magnetic flux density </Td> <Td> Wb / m </Td> <Td> kg ⋅ s ⋅ A </Td> </Tr> <Tr> <Td> henry </Td> <Td> </Td> <Td> inductance </Td> <Td> Wb / A </Td> <Td> kg ⋅ m ⋅ s ⋅ A </Td> </Tr> <Tr> <Td> degree Celsius </Td> <Td> ° C </Td> <Td> temperature relative to 273.15 K </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> lumen </Td> <Td> lm </Td> <Td> luminous flux </Td> <Td> cd ⋅ sr </Td> <Td> cd </Td> </Tr> <Tr> <Td> lux </Td> <Td> lx </Td> <Td> illuminance </Td> <Td> lm / m </Td> <Td> m ⋅ cd </Td> </Tr> <Tr> <Td> becquerel </Td> <Td> Bq </Td> <Td> radioactivity (decays per unit time) </Td> <Td> </Td> <Td> s </Td> </Tr> <Tr> <Td> gray </Td> <Td> Gy </Td> <Td> absorbed dose (of ionising radiation) </Td> <Td> J / kg </Td> <Td> m ⋅ s </Td> </Tr> <Tr> <Td> sievert </Td> <Td> Sv </Td> <Td> equivalent dose (of ionising radiation) </Td> <Td> J / kg </Td> <Td> m ⋅ s </Td> </Tr> <Tr> <Td> katal </Td> <Td> kat </Td> <Td> catalytic activity </Td> <Td> </Td> <Td> mol ⋅ s </Td> </Tr> <Tr> <Td_colspan="5"> Notes 1 . The table is ordered so that a derived unit is listed after the units upon which its definition depends . 2 . The radian and steradian are defined as dimensionless derived units . </Td> </Tr> </Table> <Tr> <Th> Name </Th> <Th> Symbol </Th> <Th> Quantity </Th> <Th> In other SI units </Th> <Th> In SI base units </Th> </Tr>

What is the si unit used to measure the temperature of a substance