Radians are dimensionless

180°= 240°

Unit conversionMetric system

SI units Common combinations of the SI units

Converting between degrees and radians

aatto-

Example: Convert the following:a) Convert 5.2 mg to kg

a) Convert 45° to radians

b) Convert π rad to degrees

b) Convert 0.00071 km to µm

(5.2 mg) = 5.2 x 10-6 kg 1 g

103 mg

10-18 10-15 10-12 10-9 10-6 10-3 10-2 10-1 100 101 102 103 106 109 1012

ffemto-

ppico-

nnano-

μmicro-

mmilli-

ccenti-

ddeci-

dadeka-

hhecto-

kkilo-

Mmega-

Ggiga-

Ttera-Base Unit

1 kg103 g

(7.1 x 10-5km) = 7.1 x 104μm 103 m1 km

106 μm 1 m

Example: Convert the following to appropriate SI Units:

Example: Perform the following conversions:

a) 10 km/h b) 450 cm2

= 2.81 h3600 s

kmh

π rad180°

45°

π rad

=

π rad

π rad4

43

43

1000 m m1 km s (450 cm2) = 0.045 m21 m

100 cm1 m

100 cm

QUANTITY UNIT SYMBOL

Length Metre

QUANTITY UNIT

Area

Volume

Velocity

Acceleration

m3

m/s

m2

m/s2

SYMBOL

J ,

NNewton

Joule

DERIVED QUANTITY NAME

Work ( )

Force ( )

EQUIVALENT SI UNITS

WWattPower ( )

AAmpere

m

180° = π rad π4

3π4

5π4

7π4

3π2

π3

π2

π

π2π0

6

10

Mass Kilogram kg

Time Second s

Electric charge

Temperature

Amount of substance

Kelvin

Mole

Coulomb

K

mol

C

Current ( )

,

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