Question

Longitude and GMT Time

1. It’s 3 pm GMT and 5 pm local time, where are
you?
2. Its 10 pm local time and 7 pm GMT where are
you?
3. Its 1 pm GMT and you are located on the 30
degree WEST longitude line, what time is it for
you?
4. A ship passes the prime meridian and finds Polaris
to have an altitude of 45 degrees, what is your
latitude and longitude?
5. It’s 2 pm GMT and 9 am local time, where are you?

Answer 1

To determine your position using local time and GMT, you calculate the time difference and multiply it by 15 to get your longitude. For example, a two-hour difference indicates a longitude of 30 degrees if ahead of GMT (east) or 30 degrees west if behind GMT.

"The correct option is approximately option 3"

Step-by-step explanation:

The question you've asked pertains to the concept of longitude and how to determine your position on the Earth's surface by knowing the local time and comparing it with Greenwich Mean Time (GMT), which is the time at the prime meridian (0 degrees longitude) located in Greenwich, England.

• If it's 3 pm GMT and 5 pm local time, you are two hours ahead of GMT, which means you're located at 30 degrees east longitude (15 degrees for each hour).
• If it's 10 pm local time and 7 pm GMT, you are three hours behind GMT, so you are at 45 degrees west longitude.
• At 1 pm GMT, if you are on the 30 degree WEST longitude line, the local time for you is 11 am (two hours behind GMT).
• A ship passing the prime meridian finding Polaris at an altitude of 45 degrees indicates that the ship's latitude is also 45 degrees north; the longitude is 0 degrees as it's at the prime meridian.
• It’s 2 pm GMT and 9 am local time, you are 5 hours behind, which puts you at 75 degrees west longitude.

The Earth is divided into 24 time zones, each roughly 15 degrees of longitude wide, and these time zones help us manage local times in relation to the Earth's rotation and its relation to the Sun.

Answer 2

To find your longitude based on GMT and local time differences, remember that every 15 degrees of longitude represents a one-hour difference from GMT. By analyzing the time differences provided, one can deduce their longitudinal position on the Earth relative to the prime meridian.

Step-by-step explanation:

Understanding time in relation to longitude and Greenwich Mean Time (GMT) requires grasping that every 15° of longitude represents one hour's difference from GMT. To determine your position in relation to GMT, you need to examine the difference between GMT and your local time. If you're located to the east of Greenwich, your local time is ahead of GMT, and if you're to the west, it's behind GMT.

1. If it's 3 pm GMT and 5 pm local time, you are 2 hours ahead of GMT. This means you are at 30° east longitude (15° for each hour).

2. If it's 10 pm local time and 7 pm GMT, then you are 3 hours ahead of GMT, placing you at 45° east longitude.

3. If it's 1 pm GMT and you're located on the 30° WEST longitude line, it is 10 am for you, because you're 3 hours behind GMT.

4. When a ship at the prime meridian finds Polaris at an altitude of 45 degrees, this indicates that the ship's latitude is also 45 degrees. The longitude is 0°, as it's at the prime meridian.

5. If it's 2 pm GMT and 9 am local time, you're 5 hours behind GMT. You are therefore located at 75° west longitude.