(a) Distinguish between local time and standard time.
(b) The local time of Town A, located on longitude 70°E and latitude 45°N, is 7.46 p.m., calculate the longitude of Town B on the same latitude when its local time is 5.30 a.m.
Explanation
(a) Differences between Local time and Standard time
1. Local time varies from one longitude to another at the rate of 4 minutes per degree of longitude whereas standard time varies from one time zone to another on hourly basis of 15° of longitude to 1 hour.
2. Standard time maintains the central time for time zone in which they are, whereas local time varies from one place to another within a time zone.
3. Standard time falls within 24 time zones whereas local time varies irregularly from longitude to longitude within each time zone.
4. Standard time is associated with Greenwich Mean Time, whereas local time is not.
(b) Calculations of Longitude
Time in town A is 7.46 p.m
Time in town B is 5.30 a.m
Time difference is 19.46 hours — 5.30 hours
Time difference is 14 hours 16 minutes
If 1 hour = 15° or 1° = 4 minutes
Therefore, 14 hours 16 minutes 7:- 214°
If town A is on longitude 70°E so town B’s time is behind
Therefore, subtract 70° from 214° = 144°W.