Physics

Problem

A motorbike moves

20\,\text{km}

east at

40\,\text{km\,h}^{-1}

and then

10\,\text{km}

west at

20\,\text{km\,h}^{-1}

. The magnitude of its average velocity for the whole journey is a)

18.2\,\text{km\,h}^{-1}

10\,\text{km\,h}^{-1}

30\,\text{km\,h}^{-1}

20\,\text{km\,h}^{-1}