(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...

Answer Details

(a) Local time versus standard time

Local time	Standard time
Time based on the position of the overhead sun for a particular meridian (longitude).	A single, uniform time adopted for a whole country or time zone.
It changes with every degree of longitude (4 minutes per degree).	It is fixed for the whole zone regardless of small changes in longitude.
Determined by a chosen central meridian's local time in each zone.	Based on a chosen standard meridian (often a multiple of 15 degrees).

(b) Longitude of Town B

Latitude is the same, so it does not affect the calculation. Use the difference in local time between the two towns.

Town A (70 degrees E): local time = 7.46 p.m. = 19:46.
Town B: local time = 5.30 a.m. = 05:30.

Time difference:

\[ 19{:}46 - 05{:}30 = 14 \text{ hours } 16 \text{ minutes} \]

Convert to minutes: \(14 \times 60 + 16 = 856\) minutes.

Since 1 degree of longitude = 4 minutes of time, the longitude difference is:

\[ \frac{856}{4} = 214^{\circ} \]

Town B's local time (05:30) is earlier (behind) Town A's (19:46), so Town B lies to the west of Town A.

Longitude of B = \(70^{\circ}E - 214^{\circ}\).

\[ 70 - 214 = -144^{\circ} \]

A negative value means we have crossed the 0 degree meridian into western longitudes:

\[ 144^{\circ}W \]

Town B lies on longitude \(144^{\circ}W\).