This is the video that kicked things off, and everything escalated from here:

Assumptions

Interval = 2 seconds.

First gaps = 0.5 meters.

Last gap = 2 meters.

Calculations

Getting per second values

Our interval is 2 seconds. Therefore we need to divide all distances by 2 to get “per second” values. Therefore

First gaps: 0.5 / 2 = 0.25 M/s.

Last gap: 2 / 2 = 1 M/s.

Getting per hour values

There are 60 seconds in a minute. And 60 minutes in an hour. We could do this in two steps by multiplying each number by 60, and then 60 again. Or we could shortcut this, but multiplying these two 60s together to give 3600, and then simply multiply each value by that. So that gives us:

First gaps: 0.25 * 3600 = 900 M/h.

Last gap: 1 * 3600 = 3600 M/h.

Getting Kilometers per hour values

At the moment, we have meters per hour. So given that we have 1000 meters in 1 kilometer, we now need to divide the numbers by 1000 to give KM/h:

First gaps: 900 / 1000 = 0.9 KM/h.

Last gap: 3600 / 1000 = 3.6 KM/h.

And that gives us our answer:

The horse began at 0.9 KM/h, and accelerated up to 3.6 KM/h.

Flaws and summary

Right, let’s kill the joke by acknowledging the flaws:

It would have been so cool if the numbers had been realistic. Since it’s a joke, I momuntarily considered changing the assumptions to make it work, but that’s too much effort for a joke.

Normally a change in speed on ticker tape shows as a gradual expansion of the gaps.

The interval is unlikely to be constant in this case, even if my assumption was accurate. In fact, this is almost certainly where the change in gap came from.