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Zorluk: KolayLocation, Size, and Political Divisions of Africa

When the local solar time along the Prime Meridian (0∘0^\circ) in West Africa is 12:00 noon, what is the local solar time in Cairo, Egypt, located at longitude 30∘E30^\circ\text{E}?

  1. A
    10:00 a.m.
  2. 2:00 p.m.Cevap
  3. C
    4:00 p.m.
  4. D
    8:00 a.m.

Cevap

The local solar time in Cairo is 2:00 p.m.
Earth rotates from west to east at a rate of 1∘1^\circ every 4 minutes (15∘15^\circ per hour). Cairo lies at 30∘E30^\circ\text{E}, which is 30∘30^\circ east of the Prime Meridian (0∘0^\circ). The time difference is 30×4 mins=120 mins30 \times 4\text{ mins} = 120\text{ mins} or 2 hours. Because Cairo is east of the Prime Meridian, local time is ahead, so 2 hours are added to 12:00 noon, yielding 2:00 p.m.

Adım Adım Çözüm

1
Calculate the longitudinal difference between the Prime Meridian and Cairo
30∘E−0∘=30∘30^\circ\text{E} - 0^\circ = 30^\circ
Determining spatial displacement in degrees of longitude is the first step in local time calculation.
2
Convert the longitudinal difference into time difference
30∘×4 minutes/degree=120 minutes=2 hours30^\circ \times 4\text{ minutes/degree} = 120\text{ minutes} = 2\text{ hours}
The Earth rotates 15∘15^\circ every hour, which equals 4 minutes4\text{ minutes} per degree of longitude.
3
Apply the east-west time direction rule (East Gain, West Lose)
12:00 noon + 2 hours = 2:00 p.m.
Places located east of the Prime Meridian experience sunrise earlier and are ahead in time.

Anahtar Kavram

Calculation of Local Time from Longitude in Africa
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Konular

Location, Size, and Political Divisions of Africa

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