two clocks/watch synchronised and after some time they will deviate so which one is faster or slower?

Question

two clocks/watch (clock A & clock B) synchronised minute for minute, seconds for seconds exactly. after 10 year passed, there's surely a deviation between both time that the clock reads, probably half a second or perhaps half a minute, so how do i determine which one is the accurate one, how do i know clock A is faster or slower or perhaps how do i determine clock B is the one which is slower or faster. supposing that i take a third clock (clock C) as reference how do i determine whether it is accurate as well. any clue? please justify

Answer 1

This is a problem of relativity. Without help it is impossible to determine which clock is wrong; maybe even both.
You have to compare with the atomic clock that defines the time for all over the world.
Th

Answer 2

You can't tell which is correct or if all are incorrect. If you take an average of three clocks and discard one if it varies widely from the other two chances are you will be nearest the true time.

Answer 3

If you use the method in which you compare it to clock three - then your experiment is only as good as your control.

I suggest using:
http://www.time.gov/
Because it is a credible site it is likely to provide a time that is fairly accurate.

Answer 4

ask the atomic time clock

Answer 5

http://www.time.gov/timezone.cgi?Eastern/d/-5/java

http://tycho.usno.navy.mil/what.html

try comparing them to the above links