motions-of-the-earthWHERE cd.courseId=10 AND cd.subId=26 AND chapterSlug='motions-of-the-earth' and status=1SELECT ex_no,page_number,question,question_no,id,chapter,solution FROM question_mgmt as q WHERE courseId='10' AND subId='26' AND chapterId='542' AND ex_no!=0 AND status=1 ORDER BY ex_no,CAST(question_no AS UNSIGNED) CBSE Class 6 Free NCERT Book Solution for Social Science - The Earth Our Habitat

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Chapter 3 : Motions of the Earth


  • Earth practices two types of motion: Rotation and Revolution.
  • Axis is an imaginary line which makes an angle of 66 ½◦.
  • Days and nights are caused due to rotation.
  • Seasons are caused due to revolution.
  • Circle of illumination is the circle which divides day from night on globe.
  • Leap year comes after every 4 years and at that time, February has 29 days. It means, earth usually have 365 days but in the leap year earth will have 366 days.
  • The longest day and shortest night is observed on 21st June.
  • 21st March and 23rd September experiences equal day and night which is known as equinox.

Exercise 1 ( Page No. : 21 )
Q:
A:

(a) The angle of inclination of the Earth’s axis with its orbital plane is 66 ½◦.

(b) Rotation:

  • The movement of the Earth on its axis is called rotation.
  • The Earth takes 24 hours to complete one rotation.
  • Days and nights are caused due to rotation of the Earth.

Revolution:

  • The movement of the Earth around the sun in a fixed path or the orbit is called revolution.
  • The Earth takes 365 days six hours to complete one revolution.
  • Seasons are caused due to revolution of the Earth.

(c) A year with 366 days is called leap year. It occurs once in four years on the month of February and it is 29th day of that month. It is also called intercalary year. The Earth do not take exact 365 days in an year and 24 hours in a day, so we add them as one extra day once in four year.

(d) Differences between summer and winter solstice are as follows:

                Summer Solstice

                     Winter Solstice

Summer solstice occurs on 21st June in Northern Hemisphere.

Winter Solstice occurs on 22nd December in Southern Hemisphere.

The Northern Hemisphere experiences more heat and light.

Southern Hemisphere experiences less heat and light.

It is summer in Northern Hemisphere.

It is winter in Southern Hemisphere.

Days are longer and nights are shorter.

Nights are longer and days are shorter.

(e) On 23rd September and 21st March, the rays of sun directly falls on the equator. So, at that position neither of the poles are tilted. So at that specific or we can say a particular day the earth experiences equal days and nights and this is called as equinox.

(f) The Southern Hemisphere experience winter and summers solstice in different times than that of the Northern Hemisphere because:

  1. Southern Hemisphere is tilted towards the Sun on 22nd December, so summer Solstice is there in Southern Hemisphere. At that time Winter Solstice is in Northern Hemisphere.
  2. In 21st June the Northern Hemisphere is tilted towards the Sun, so Summer Solstice is there and Winter Solstice is in the Southern Hemisphere.

(g) The poles experiences about six months day and six months night because:

  1. When Northern Hemisphere is tilted towards the Sun, The North Pole remains in the light for the whole day. This position remains for six months from 21st March- 23rd September.
  2. On the same time Southern Hemisphere is away from the Sun, the South Pole does not get light for six months. So it experiences night for six months and vice versa.

Exercise 1 ( Page No. : 21 )
Q:
A:

(a) (ii) Revolution

Seasons are caused due to revolution of the earth around the sun. Revolution is a movement of earth near the sun on a fixed path (orbit) in an elliptical way.

(b) (i) 21 March

On 21st March, the rays of sun directly fall on the equator. So at that particular day, the earth is not tilted towards any pole and experiences an equinox (equal days and nights).

(c) (iii) Australia

As Australia is present in the Southern Hemisphere so during December Australia experience summer due to revolution. And, in same manner at that time the Northern hemisphere experiences winter.

(d) (ii) Revolution

As earth revolves around the sun in an elliptical path, so it cause change in season.


Exercise 1 ( Page No. : 21 )
Q:
A:

(a) 29

There are 29 days in February once in every four year which is an additional day of the year, also called the leap year.

(b) Rotation

Rotation is the daily motion of the earth. The earth completes one rotation in 24 hours. Days and nights are cause due to rotation of the earth.

(c) Elliptical

Elliptical shape is something like oval. The orbit of the planets is an elliptical path. It is not a complete circle.

(d) Cancer

On 21st June, the Northern Hemisphere gets tilted towards the sun. So, the rays of sun directly fall on the Tropic of Cancer (23½◦N).

(e) Winter

Due to summer solstice, the days get shorter and nights get longer than the days.


NCERT Solutions for Class 6 Social Science - The Earth Our Habitat

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