Q 1. Two boxes in different hemispheres are given in the following diagram. The IDL passes through both the boxes. In one box, the meridian, day and date is given. Find the day and date for the other box.
Ans.
Q 2. Select the correct option :
(1) While crossing the IDL, a person will have to add one day when travelling from
(a) East to West
(b) West to East
(c) South to North
(d) North to South
Ans.
(a) East to West
(2) If it is Wednesday 10 a.m. at 15° E meridian, then what will be the time at IDL?
(a) Wednesday 6 a.m.
(b) Wednesday 9 p.m.
(c) Thursday 2 p.m.
(d) Thursday 6 p.m.
Ans.
(b) Wednesday 9 p.m.
(3) According to the international convention, at which meridian does the day and date change occurs?
(a) 0°
(b) 90° E
(c) 90° W
(d) 180°
Ans.
(d) 180°
(4) At which direction of the IDL does a new day start immediately?
(a) East
(b) West
(c) North
(d) South
Ans.
(b) West
(5) IDL brings coordination in which of the following?
(a) GPS system
(b) Defence departments
(c) Transportation schedules
(d) Determining the hemisphere
Ans.
(c) Transportation schedules
Q 3. Give geographical reasons.
(1) IDL is proving to be very useful in today’s times.
Ans. IDL is proving to be very useful in today’s times because:
(1) The IDL brings coordination between international airlines, transportation services, economic and trade activities. (2) We can keep a track of all the calculations of day and time accurately with the help of IDL in case of global transportation esp. with respect to airways. (3) It is only because of the IDL that the schedules of the traffic worldwide are organised properly.
(2) The day starts in Pacific Ocean on the earth.
Ans. The day starts in Pacific Ocean on the earth because:
(1) IDL is drawn with reference to 180° meridian which passes through the Pacific Ocean. (2) The sun rises from the east hence all the countries and geographical features to the east experience sun first. (3) Pacific being to the east sees the sun first.
Q 4. Write in brief:
(1) What considerations have been made while deciding the IDL?
Ans. The following points were taken into consideration while drawing The International Date Line.(IDL):
(a) The direction of travel
(b) The current day and date
(1) Accordingly, while travelling from Japan to America, we need to consider the existing day and date even after crossing the IDL. For example, if it is Thursday 25th December, then Thursday 25th December only should be considered. (2) On the contrary, while going from America to Japan, and crossing the IDL, one needs to add a day to the date. So if it is Thursday, 25th December then it will be Friday, 26th December.
(2) While crossing the IDL, what changes will you make?
Ans. (1) If IDL is crossed while travelling from east to west, one day has to be added to the day of commencing the journey. (2) But if IDL is crossed while travelling from west to east, the same day is considered upon arrival.
(3) Why is the IDL not a straight line like the 180° meridian?
Ans. (1) An attempt has been made to make the IDL pass through the Pacific Ocean completely. (2) Had it passed through land or some islands, the people there would have had to follow different dates and timings because dates would have been different on their eastern and western parts. (3) Also, it would have been difficult to know when one crosses the IDL on land and when the date changes on the calendar.(4) Therefore, the IDL is not a straight line like the 1800 meridian.
(4) Why doesn’t the IDL pass through land?
Ans. (1) If the IDL had passed through a land or some islands, the people there would have had to follow different dates and timings because dates would have been different on their Eastern and Western parts. (2) Also, it would have been difficult to know when one crosses the IDL on land and when the date changes on the calendar. (3) Hence, the IDL does not pass through land.
(5) Why is the IDL considered with respect to the 180° meridian only?
Ans. (1) Our 24-hour day starts at 12 midnight. Because of the earth’s rotation, midnight occurs at different times at different places. (2) As the earth is spherical in shape, every place has a place to its east. then at what location to the east does the day start on the earth? (3) To get an answer to many questions like this, representatives of many nations got together, under the leadership of American professor Davidson in the year 1884 and decided on the International Date Line. (4) The line was drawn opposite to the Greenwich Prime Meridian i.e. with reference to the 180° meridian. (5) Hence, the IDL considered with respect to the 180° meridian only.
Q 5. Using an atlas, tell in which of the following routes the IDL will be crossed and show them on the map.
(1) Mumbai- London- New York- Los Angeles- Tokyo
(2) Delhi- Kolkata- Singapore- Melbourne
(3) Kolkata- Hong Kong- Tokyo- San Francisco
(4) Chennai-Singapore- Tokyo- Sydney Santiago
(5) Delhi-London-New York
Ans.
(1)
(2)
(3)
(4)
(5)