Self Practice Questions

(i)

• The longitude difference: 2° - 0° = 2°
• For 1° longitude difference time difference is 4 minutes.
• So, for 2° longitudinal difference, the time difference is 2° x 4 = 8 minutes.
• As the given place is situated in the east Greenwich, the local time at 2° East will be : 7 a.m. + 8 minutes = 7:08 a.m.

(ii)

• The longitude difference: 25° - 0° = 25°
• For 1° longitudinal difference time difference is 4 minutes.
• So, for 25° longitudinal difference, the time difference is 25° x 4 = 100 minutes or 1 hour 40 minutes.
• Since the given place is situated in the east of Greenwich, the local time at 26° East will be: (7 a.m. + 1 hour 40 minutes) = 8:40 a.m.

• The longitudinal difference: 50° + 13° = 63°
• For 1 longitudinal difference time difference is 4 minutes.
• So, for 63° longitudinal difference, the time difference is 63° x 4 = 252 minutes or 4 hours 12 minutes.
• As the given place is situated in the west of 50° east longitude, the local time at 13° west will be: (11 a.m. - 4 hours 12 minutes) = 6:48 a.m.

• The longitudinal difference: 30° + 30° = 60°.
• For 1° longitudinal difference is 4 minutes.
• So, for 60° longitudinal difference, the time difference is: 60° x 4 = 240 minutes or 4 hours.
• As the given place is situated in the west of 30° East longitude, the local time at 30° west will be: (8 a.m. - 4 hours) = 4 a.m.

• The longitudinal difference between New York and Nigeria is: 75° + 15° = 90°
• For 1° longitudinal difference time difference is 4 minutes.
• So, for 90° longitudinal difference, the time difference is: 90° x 4 = 360 minutes or 6 hours.
• As New York is situated in the west of Nigeria, the local time at New York will be: ( 10 a.m. - 6 hours) = 4 a.m.

• The longitudinal difference: 60° + 90° = 150°
• For 1° longitudinal difference time difference is 4 minutes.
• So, for 150° longitudinal difference, the time difference is 150° x 4 = 600 minutes or 10 hours.
• As the given place is situated in the west of 90° east longitude, the local time at 60° west will be: (5:30 a.m. - 10 hours) = 7:30 p.m. on Thursday.

Calculating time at Prime Meridian (0°) —

• The longitudinal difference: 40° - 0° = 40°
• For 1° longitudinal difference time difference is 4 minutes.
• So, for 40° longitudinal difference, the time difference is 40° x 4 = 160 minutes or 2 hours 40 minutes.
• Since the Prime Meridian (0°) is situated to the east of 40° west longitude, the local time at Prime Meridian (0°) will be: (12 a.m. + 2 hours 40 minutes) = 2:40 a.m.

Calculating time at 50° East longitude or City A —

• The longitudinal difference: 50° - 0° = 50°
• For 1° longitudinal difference time difference is 4 minutes.
• So, for 50° longitudinal difference, the time difference is 50° x 4 = 200 minutes or 3 hours 20 minutes.
• Since the 50° East longitude or City A is situated to the east of Prime Meridian (0°), the local time at City A will be: (2:40 a.m. + 3 hours 20 minutes) = 6 a.m.

The Earth rotates 360° in 24 hours, which means it turns 15° of longitude every hour (360° ÷ 24 = 15°). Therefore, for every 15° of longitude travelled east or west, there is a 1-hour difference in local time.

• If you move eastward, the time increases by 1 hour for every 15°.

• If you move westward, the time decreases by 1 hour for every 15°.

The Prime Meridian (0°) passes through the Royal Astronomical Observatory at Greenwich village, near London. So, in 1884, it was decided by all countries to adopt the local time of Prime Meridian (0°) worldwide.

Hence, when sun is directly overhead at 0° longitude and it is 12 o'clock (noon) there, the international time is calculated east or west of the Prime Meridian with reference to this time.

(i) The 0° meridian is known as the Prime Meridian.

(ii) Point A is located at 30°N latitude and 60°E longitude.

1. Earth's grid
2. Prime meridian
3. Temperate Zone
4. Tropic of Capricorn