Using the longitude of a time zone’s central meridian (which has been provided f
ID: 285768 • Letter: U
Question
Using the longitude of a time zone’s central meridian (which has been provided for you), answer the following questions. Be sure to indicate if the time is A.M. or P.M.; however, refer to “noon” or “midnight” rather than to 12:00 P.M. or 12:00 A.M. It may be helpful to draw a simple diagram, such as Figure 3-3, when making your calculations.
1. If it is 10:00 A.M. Monday in Denver (based on 105 degrees W), what time and day is it in New York City (75 degrees W)?
2. If it is 11:00 A.M. Thursday in Seattle (120 degrees W), what time and day is it in Seoul, South Korea (135 degrees E)?
3. A satellite image of the United States was taken at “0900Z.” What was the local standard time in Chicago (90 degrees W)?
4. If it is Friday at 3:00 P.M. daylight-saving time in Kansas City (90 degrees W), what is the day and time in Quito, Ecuador (75 degrees W), where daylight-saving time is not being observed?
Explanation / Answer
1. If it is 10:00 A.M. Monday in Denver (based on 105 degrees W), what time and day is it in New York City (75 degrees W)?
Ans. Denver (105 degrees W), time is = 10:00 A.M.
New York City (75 degrees W).
Longitude difference = (105 - 75) = 30 degrees.
Time difference for each degree of longitude is = 4 minute.
So, time difference for 30 degrees of longitude is = 30 * 4 = 120 minute. = 2 hours
If you are on the 105 degrees W, 75 degrees W is in your eastward.
So, time and day in New York City is = (10:00 A.M. + 2 hours) = 12 P.M. and day is Monday. So, it is Monday noon.
2. If it is 11:00 A.M. Thursday in Seattle (120 degrees W), what time and day is it in Seoul, South Korea (135 degrees E)?
Ans. Seattle (120 degrees W), time is = 11:00 A.M. Thursday.
Seoul, South Korea (135 degrees E).
Longitude difference = (120 + 135) = 255 degrees.
Time difference for 255 degrees of longitude is = 255 * 4 = 1020 minute. = 17 hours.
So, the time in Seoul, South Korea is = (11:00 A.M. + 17 hours) = Friday at 4 A.M.
3. A satellite image of the United States was taken at “0900Z.” What was the local standard time in Chicago (90 degrees W)?
Ans. 0900Z means Zulu Time Zone, UTC±0, 09:00 A.M.
Time Zone of Chicago (90 degrees W) is UTC-06:00 [(90*4)/60 = 6 hours]
So, it is (09:00 A.M. - 6 hours) = 03:00 A.M. in Chicago.
4. If it is Friday at 3:00 P.M. daylight-saving time in Kansas City (90 degrees W), what is the day and time in Quito, Ecuador (75 degrees W), where daylight-saving time is not being observed?
Ans. Kansas City (90 degrees W), it is Friday at 3:00 P.M.
Quito, Ecuador (75 degrees W)
Longitude difference = (90 -075) = 15 degrees.
Time difference = 15 * 4 = 60 minute = 1 hour.
So, date and time in Quito, Ecuador (75 degrees W) is = (3:00 P.M. + 1 hour) = Friday at 4:00 P.M.
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