As others have said, CM is length and SECONDS is time, but SECONDS is also something else, a measure of an arc, part of a circle. There are 360 degrees to a circle, 60 subdivisions with each degree which are minutes and 60 divisions within each minute which are seconds for a total of 1296000.seconds of arc which make up the circle. Now, if you know the circumference of the circle (or diameter which you multiply by PI to get circumference) you can determine how many seconds are encompassed by a length of 5 CM along the circumference of the circle. For example, if my circle has a circumference of 2 meters (200 CM), my 5 CM is 5/200*1296000 = 32400 arc seconds. If my circle has a circumference of 3.141592 meters (1 meter diameter) it would be 5/314.1592*1296000 = 20626.484 arc seconds. Time and length can not be converted back and forth, but length and arc-seconds CAN be as I have shown, but you need additional information to make the exact calculation. In navigation, latitude and longitude are expressed in degrees, minutes and seconds (or degrees and decimal fractions of a degree).