What conversion factor is used to convert 10 hours to seconds?

hours \,\times\, (\frac {minutes}{hours}) \,\times\,(\frac {seconds}{minute})\,\,=\,seconds

Note how the units will cancel.
We know there are 60 minutes in an hour. We also know that there are 60 seconds in a minute so

For "X" seconds,

X\,hours \,=\, X\, hours \,\times\, (\frac {60\, minutes}{hour}) \,\times\,(\frac {60\, seconds}{minute})\,\,=\,3600 \, X \, seconds

In other words, there are 3600 seconds in one hour (60 x 60 = 3600). You multiply the number of hours by 3600 and you'll have the number of seconds.