Okay, what we're trying to do here is convert a speed from meters per second to kilometers per hour. Here are the steps we'd take in order to do that.
First we'll set up a simple conversion problem. As we know, there are 1000 meters in a kilometer. This means that our numerical answer in Kilometers will be 1000 times smaller than our answer in meters! If we traveled 5120 meters in a second, that means we went 5.12 kilometers per second (the decimal version of 5120/1000).
However, we aren't finished yet. we need the amount of kilometers we traveled in an hour, not a second. since we have 60 seconds in a minute, and 60 minutes in an hour, we can take 60*60 and get 3600, or in other words, since there are 3600 seconds in an hour, our answer needs to be 3600 times larger.
So, we take the 5.12 km we got in the first step and multiple it by 3600. Punch that into a calculator and you'll get the answer: 18,432 km/h.
Here's the above information in a conversion formula form you can use quickly for other problems.
5120m/s * 1km / 1000m * 3600s / 1h = 18,432,000km / 1000h , which we can simplify to 18,432km / 1hr (remember to cross out like terms such as seconds and meters to get rid of them) which is just another way of writing 18,432 km/h.