question_answer

Two clocks are being tested against a standard clock located in a national laboratory. At 12:00:00 noon by the standard clock, the readings of the two clocks are:  

Day	Clock 1	Clock 2
Monday	\[\text{12}:00:0\text{5}\]	\[\text{1}0:\text{15}:0\text{6}\]
Tuesday	\[\text{12}:0\text{1}:\text{15}\]	\[\text{1}0:\text{14}:\text{59}\]
Wednesday	\[\text{11}:\text{59}:0\text{8}\]	\[\text{1}0:\text{15}:\text{18}\]
Thursday	\[\text{12}:0\text{1}:\text{5}0\]	\[\text{1}0:\text{15}:0\text{7}\]
Friday	\[\text{11}:\text{59}:\text{15}\]	\[\text{1}0:\text{14}:\text{53}\]
Saturday	\[\text{12}:0\text{1}:\text{3}0\]	\[\text{1}0:\text{15}:\text{24}\]
Sunday	\[\text{12}:0\text{1}:\text{19}\]	\[\text{1}0:\text{15}:\text{11}\]

    If you are doing an experiment that requires precision time interval measurements, which of the two clocks will you prefer?

Answer:

                The range of variation over the seven days of observations is 162 s for clock 1, and 31s for clock 2. The average reading of clock 1 is much closer to the standard time than the average reading of clock 2. The important point is that a clock's zero error is not as significant for precision work as its variation, because a 'zero-error' can always be easily corrected. Hence clock 2 is to be preferred to clock 1.