On 12 November, you are taking a time tick using the 1600 GMT BBC Broadcast. You hear five pulses followed by a longer pulse. At the start of the longer pulse you start a stopwatch. You stop the stopwatch at the same time reading the chronometer with the following results: stopwatch 03m 19s, chronometer 15h 59m 46s. What is the chronometer error?
• How a radio time tick works: the start of the long pulse marks an exact whole minute (in this case, 1600:00 GMT) • Difference between GMT (true time) and chronometer time using the stopwatch elapsed time • How to express chronometer error as fast or slow relative to GMT
• First, decide what exact GMT time corresponds to the moment you stopped the stopwatch, given you started it at 1600:00 GMT and it ran for 03m 19s. • Next, compare that GMT time to the chronometer reading at that same instant: is the chronometer showing an earlier or later time than GMT? • Finally, convert the difference into minutes and seconds and decide whether the chronometer is fast (reading later) or slow (reading earlier) compared to GMT.
• Be sure you are using the start of the long pulse as 1600:00 GMT, not 15h 59m 46s. • Carefully check whether you are subtracting chronometer time minus GMT or GMT minus chronometer time—this determines fast vs slow. • Confirm the magnitude of the time difference matches one of the choices in both minutes and seconds before deciding.
No comments yet
Be the first to share your thoughts!