# Choose Your Units

##### Age 14 to 16

Challenge Level

### Phenomena to units

Volume of a bacterium - Cubic micrometres $\mathrm{\mu m}^3$

Mass of an oak tree - Tonnes $(10^3\textrm{ kg})$

Area of a leaf - Square centimetres $(\textrm{cm}^2)$

Half-life of Uranium-235 - Millions of years

Area of a football pitch - Hectares

Average life-span of a human -Years

Volume of a bath tub - Cubic metres $(\textrm{m}^3)$

### Units to phenomena

Millimetre - size of an amoeba

Newton - weight of an apple

Angstrom - atomic diameter of a hydrogen atom

Joule - kinetic energy of a table tennis ball travelling at
$100\textrm{ km h}^{-1}$

Volt - voltage across an AA cell

Microgram - mass of $1\textrm{ mm}^3$ of air

Micrometre - mitochondrion

Hertz - frequency of tick-tock on a clock

Parsec - distance to Proxima Centauri (closest star other than the
Sun)