Welcome to the exam room — this chapter is about things that move, and it stars exactly three characters. A distance is ground covered: it wears metres ($\mathrm{m}$) or kilometres ($\mathrm{km}$). A time is the clock running: seconds, minutes, hours. And a speed is the two of them folded into one number — how much ground per tick of the clock — wearing $\mathrm{m/s}$ or $\mathrm{km/h}$. That little slash is the word per, said out loud: “metres per second”.

Here is the trick that will carry you through every question below: read the units first. They are the quantity's name tag. A slash means a rate; a bare m or km means ground; a bare s, min or h means the clock. You never have to guess what a number is — it is already telling you.