CHAPTER – 2 * Locating Places on the Earth and Finding Time

1. Q) What is a grid?

A: A grid is a set of horizontal and vertical lines that criss-cross each other and form a network.

 

1. Q) Define the terms: parallels of latitude and meridians of longitude.

A: A set of imaginary circular lines drawn horizontally between the two poles and parallel to the Equator and to each other are called parallels of latitude.  They run in an east-west direction. Another set of imaginary lines drawn vertically from the North Pole to the South Pole are called meridians of longitude.

 

1. Q) What is the 0^olatitude referred to us?

A: The Equator, being the starting point, is considered to be 0^o latitude. The angular distance of either of the poles from the Equator is 90^o. Therefore, the North Pole is marked as 90^oN Latitude while the south Pole is marked as 90^oS latitude.

 

1. Q) What is the Greenwich Mean Time?
2. Q) Define heat zone?

A: Since the earth is spherical, the rays of the sun become more and more slanting as we move away from the equator and towards the poles. Direct rays give more heat than slanting rays. The Earth can be divided into three zones on the basis of the amount of heat received from the Sun. These are the heat zones.

 

1. Q) What is the distance between two degrees of longitude?

A: The distance between two degrees of longitude is 111 km.

 

1. Q) What is the importance of local time in daily life?

A: All places located on the same meridian see the sun at the same position in the sky. This is the local time for that meridian.

 

1. Q) What is the differences in and need for time zones?

A: Since the Earth takes 24 hours to complete one rotation, twenty-four time zones of one hour each were demarcated.

 

1. Q) What is the significance of latitudes and longitudes?

A: The latitude of a place is the angular distance of that place north or south of the Equator measured from the centre of the Earth. The longitude is the angular distance of that place east or west of the Prime Meridian. The point of intersection of a parallels of latitude and meridians of longitude gives the exact location of a place.

 

Numerals

1. Q) What is the time and day at a certain place on 30^oW longitude when it is 8 AM on Tuesday at a place 110^oE longitude?

A: 30+110 = 140^o towards west

1 degree = 4 minute

So 140 degree = 140*4 = 560 minutes = 9 hours and 20 minutes

As the place is towards west, so to get the time of place

= 8 AM Tuesday – 9 Hours and 20 Minutes = 10:40 PM Monday

 

1. Q) If a cricket test match starts at Melbourne (145^oE) at 10 AM when shall we, in India, tune in to our television sets to watch it?

A: The longitude of India is 82.5^oE.

145^o – 82.5^o = 62.5^o

We know that 1^o = 4 minutes

So 62.5^o = 62.5 X 4 = 250 minutes

As India is towards west of Melbourne so 250 minutes or 4 hours and 10 minutes will be subtracted from Melbourne time.

So time at India is             = 10 AM – 4 Hours and 10 Minutes

= 5:50 AM

 

1. Q) It is noon at a place when it is 9 AM at Greenwich. Calculate the longitude of that place.

A: The difference of 12 Noon and 9 AM is 3 Hours.

4 minutes = 1 degree

So 3 Hours = 180/4 = 45 degrees

Since 12 Noon is greater than 9 AM so the place is towards east of Greenwich. Means 45^oE

 

1. Q) It is 6 PM at a place 10^oW (S), When it is 1 PM at a certain place (R). Calculate the longitude of R.

A: 6 PM – 1 PM = 5 Hours

4 minutes = 1 degree

So 5 hours = 300 minutes = 300 / 4 = 75 degrees

As 1 PM is less the 6 PM so Place R is towards west of place S

So longitude of place S = 10^oW+75^o = 85^oW

 

Fill up the blanks

1. The point of intersection of a parallel and a meridian gives the exact location of a place.
2. The imaginary line on which our earth rotates is called its
3. The ends of an axis are known as
4. The pole towards the north is called the North Pole and the pole towards the south is called the south pole.
5. The imaginary line that forms a circle around the surface of the Earth and is exactly midway between the two poles and perpendicular to the axis is called
6. The part of the Earth that lies to the north of the Equator is called the Northern Hemisphere and the part to the south is called the southern Hemisphere.
7. The Equator is the longest parallel.
8. The parallel of 23^oN, called the Tropic of Cancer.
9. The parallel of 23^oS, called the Tropic of Capricorn.
10. The parallel of 66^oN, called the Arcatic Circle.
11. The parallel of 66^oS, called the Antarctic Circle.
12. The three heat zones are Torrid zone, Temperate zone, Frigid Zone.
13. The Torrid zone is the hottest zone on the Earth because it receives direct rays of the Sun throughout the year.