*This question might had to do with the introduction of the absolute scale.
- Consider the planet that travel around the star, the length for it to complete the orbit was in the range of the years.(The magnitude of the speed of the earth around 100m/s.)
- Then consider the rain drops, it's in the range of minutes. (the speed might be around 10 m/s. )
- Then consider the the particles doing the brownian motion.(The speed might be around 0.1 to 100 m/s )
- Then consider the electron move in the copper around 0.1 cm/s
- and an "effective speed"(whatever that meant) of 2000 km/s inside a hydrogen atom.
It provided an intuition that the smaller the object, the easier it moved.(Which of course made sense because it's smaller.) However, notice that those effects were mainly statistical, and even if one consider the manmade object such as the hypersonic jets the exhaust was still faster.
Further, one should take into the account that the object's size was smaller even when it had a faster speed, this brought an astronomical change of $$\frac{v(\text{speed})}{(\text{size})}$$
Why the things small seemed to move faster?