To find out what fraction of an hour a second is, you can set up the following calculation:

Number of seconds in an hour / Number of seconds in a second

There are 60 seconds in a minute, and 60 minutes in an hour, so:

Number of seconds in an hour = 60 seconds/minute * 60 minutes/hour = 3600 seconds

Now, calculate the fraction:

Number of seconds in a second = 1 second

Fraction = 1 second / 3600 seconds = 1/3600

So, a second is 1/3600th of an hour.

To express it as a decimal, divide 1 by 3600:

1 / 3600 ≈ 0.00027777777 (rounded to six decimal places)

So, a second is approximately 0.00027777 of an hour.