Name: The Importance of Standard Time
Uploaded: 2019-07-19
Duration: 4 min 21 s
Description: Time zones vary from place to place. To maintain uniformity, countries adopt standard time. But what is India's standard time, and how is it measured?

Question

What is the relationship between longitude and time? Give examples.

Accepted Answer

With the help of longitudes, we can very easily calculate the local time of a place. The longitude of Greenwich, a place near London in England, has been accepted as $0$ $°$ . The earth rotates on its axis once in $24$ hours. It means that it takes $24$ hours to pass through $360 °$ of longitude. So, it takes $4$ minutes to pass through $1 °$ longitude. Thus, if we know the meridians of longitude of two places, we can find out the difference in their local times. As the earth rotates from west to east, the local time of places to the east of Greenwich will be ahead of Greenwich time and the local time of places to the west of Greenwich will be behind Greenwich time.

Examples: The longitude of Delhi is $77 °$ E. It means there shall be a difference of $77 \times 4$ $= 308$ minutes or $5$ hours and $8$ minutes between the local time of Greenwich and Delhi. If it is $12$ o'clock noon at Greenwich, the time at Delhi shall be $5$ hours and $8$ minutes ahead of Greenwich because it lies to the east of Greenwich. It shall be $= 12 + 5$ hours and $8$ minutes = $17 : 08$ hour or $5 : 08$ p.m. at Delhi.

The local time of New York ( $74 °$ W) when it is noon at Greenwich. There shall be a difference of $74 \times 4 =$ $296$ minutes or $4$ hours and $56$ minutes between the timings of Greenwich and New York. As New York lies to the west of Greenwich its time shall be $4$ hours $56$ minutes behind that of Greenwich. It shall be $12 - 04$ hours and $56$ minutes $= 7 : 04$ a.m. at New York.

What is the relationship between longitude and time? Give examples.

Important Questions on Latitudes and Longitudes

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