(a) Distinguish between (i) Latitude and Longitude (ii) Standard Time and Greenwich Mean Time (b) If the Greenwich Mean Time is 10:00am, 5th July when Local...

Answer Details

(a)(i) Latitude and Longitude

Latitude is the angular distance of a place north or south of the Equator, measured in degrees from the centre of the earth. Lines of latitude (parallels) run from west to east, extend from \(0^\circ\) at the Equator to \(90^\circ\)N and \(90^\circ\)S, and are used to calculate distance between places. Longitude is the angular distance of a place east or west of the Greenwich (Prime) Meridian. Lines of longitude (meridians) run from north to south at right angles to the parallels, extend from \(0^\circ\) to \(180^\circ\)E and \(180^\circ\)W, and are used to calculate local time.

(a)(ii) Standard Time and Greenwich Mean Time

Standard Time is the uniform time adopted by a whole country, usually taken from a chosen central meridian, so that the entire country keeps one clock time and avoids the confusion of many different local times from town to town. For example, Nigeria adopts the meridian \(15^\circ\)E and is one hour ahead of GMT. Greenwich Mean Time (GMT) is the local time along the Prime (Greenwich) Meridian, longitude \(0^\circ\). It is the world reference time from which all countries reckon their own time.

(b) Longitude of place X

Step 1: Find the time difference. From 4:48 a.m. on 4th July to 10:00 a.m. on 5th July is \(29\text{ h }12\text{ min}\). Removing the one full day (24 h) that separates the two dates leaves an actual clock difference of:

\[29\text{ h }12\text{ min} - 24\text{ h} = 5\text{ h }12\text{ min}\]

Step 2: Convert the time difference to longitude (\(15^\circ = 1\) hour, \(1^\circ = 4\) minutes):

\[5\text{ h} = 5 \times 15^\circ = 75^\circ\]

\[12\text{ min} = \frac{12}{4}^\circ = 3^\circ\]

\[\text{Total} = 75^\circ + 3^\circ = 78^\circ\]

Step 3: Since the local time at X is behind GMT, X lies west of the Prime Meridian. Therefore the longitude of place X is \(78^\circ\)W.