In my recent post about calculating the speed of light, I mentioned Ole Roemer's calculation in 1676. The basic idea uses the orbit of one of Jupiter's moons. The orbital period is constant, but there ...

Units of speed are always a unit of length per unit of time. Different units of length and time may be chosen depending on the situation. This makes it easier to read the measurements. For example, ...

The total length of the bar represents both the total distance and the total time taken. The bar is divided into parts. Each part represents the speed as a distance per unit of time. The number of ...

You might already know that the speed of light is 299,792,458 meters per second, but now you can confirm that number by playing kitchen scientist and melting chocolate. And then eating the results.