# DAV Class 6 SST Chapter 4 Question Answer – The Motions of the Earth (Day-Night and Seasons)

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## DAV Class 6 SST Ch 4 Question Answer – The Motions of the Earth (Day-Night and Seasons)

### DAV Public School Class 6 SST Chapter 4 Question Answer – The Motions of the Earth (Day-Night and Seasons)

Something To Know

A. Tick (✓) the correct option.

Question 1.
On 22nd December, the sun rays are vertical at the
(a) Tropic of Cancer
(b) Tropic of Capricorn
(c) Equator
(d) Arc lie Circle
(b) Tropic of Capricorn

Question 2.
Which statement about a leap year is incorrect?
(a) it has 3b6 days in a year.
(b) one extra day is added in February.
(c) February has 28 days.
(d) it comes in every fourth year.
(c) February has 28 days.

Question 3.
If there is noon on one side of the earth, the opposite side will have
(a) morning
(b) evening
(c) mid-night
(d) twilight
(c) mid-night

Question 4.
On 23rd September, mid-day sun is overhead at the
(a) Equator
(b) Tropic of Cancer
(c) Tropic of Capricorn
(d) Antarctic Circle
(a) Equator

Question 5.
The angle of sun rays on 21st June on the Tropic of Cancer is
(a) 66 1/2°
(b) 90°
(c) 231/2°
(d) 50°
(b) 90°

B. Fill in the blanks.

1. The earth revolves around the sun in a fixed path called as …………….
2. The angle of inclination of the earth’s …………… axis is with its orbital plane.
3. Two motions of the earth are ………….. and ……………
4. The time of sunrise is called …………….
5. The earth completes one revolution around the sun in …………… days and …………… hours.
1. axis
2. 66 1/2°
3. rotation; revolution
4. morning
5. 365

C. Match the following:

 1. The duration of the day and night is equal in both the hemispheres on (a) Southern Hemisphere 2. The Arctic Circle has six-month long days in (b) on 21st June and 22nd December respectively 3. The Tropic of Capricorn is located in (c) summer solstice 4. The rays of the sun are vertical on Tropic of Cancer and Tropic of Capricorn (d) vernal equinox 5. Spring equinox is also called (e) 23rd September and 21 st March

 1. The duration of the day and night is equal in both the hemispheres on (e) 23rd September and 21 st March 2. The Arctic Circle has six-month long days in (c) summer solstice 3. The Tropic of Capricorn is located in (a) Southern Hemisphere 4. The rays of the sun are vertical on Tropic of Cancer and Tropic of Capricorn (b) on 21st June and 22nd December respectively 5. Spring equinox is also called (d) vernal equinox

D. Answer the following questions in brief.

Question 1.
What is rotation? How much time does the earth take in completing one rotation?
The spinning of the earth on its own axis is called rotation. The earth takes 24 hours in completing one rotation.

Question 2.
What is meant by the revolution of the earth?
The movement of the earth around the sun is an elliptical orbit is called revolution. The revolution of the earth around the sun causes seasons.

Question 3.
What is a leap year?
The year in which Februaiy is of 29 days instead of 28 days is called a leap year.

Question 4.
What is an equinox? Which seasons are indicated by it in both the hemispheres?
Equinox refers to the phenomenon when all places on the earth experience equal days and equal nights. It is autumn season in the Northern Hemisphere. Therefore, this position in Northern Hemisphere is known as autumnal equinox. At the same time, the Southern Hemisphere has spring season called vernal equinox.

Question 5.
Why does the duration of day and night change in a year?
Because the earth revolves around the sun with its axis always inclined at 66V2°.

E. Answer the following questions.

Question 1.
Why are days and nights are equal on 21st March at all places on the earth? Explain.
On 21st March, direct rays of the sun fall on the equator. At this position, neither of the poles is tilted towards the sun. As a result, all places of the earth experience equal days and equal nights.

Question 2.
Explain with the help of a diagram, why seasons are reversed between Northern and Southern Hemispheres.
The revolution of the earth around the sun causes seasons. When the earth revolves around the sun, its axis is inclined to one side. As a result, the Northern Hemisphere remains inclined towards the sun for some period of the year. As the rays of the sun are more vertical and have longer duration, the Northern Hemisphere receives more heat and therefore, it is summer season here.

The length of the day is more than night. The situation in the Southern Hemisphere is just the opposite. The rays of the sun are more slanting and, therefore, it is winter here. The nights are longer than days. The revolving earth after three months comes to a position when the sun shines vertically over the equator. The days and nights are of equal duration in both the hemispheres.

It is autumn in the Northern Hemisphere and Spring in the Southern Hemisphere. The earth continues to move further and comes to a position after three months that the rays of the sun are vertical again over the equator. The Northern Hemisphere enjoys spring season while there is autumn in the Southern Hemisphere. In this way, seasons are reversed between Northern and Southern Hemispheres.

Question 3.
Why does the month of February have 29 days, after every four years? Explain.
The earth completes one revolution in 365 days and about 6 hours. For our convenience, we consider 365 days in a year. The remaining 6 hours are added over a period of four years till they become 24 hours or one day. This extra day is added to the month of February every 4 years to make it a month of 29 days instead of 28 days. Therefore, the year of 366 days is called a leap year.

Question 4.
How do day and night occur on the earth? Explain with the help of a diagram.
The earth completes one rotation in about 24 hours. It faces the sun while rotating from west to east. Each part of the earth facing the sun, is illuminated by sunlight turn by turn. The lighted part of the earth that faces the sun has day while the other part of the earth that is not facing sun, experiences night. Thus, as the earth rotates, the day follows the night and the night follows the day turn by turn.

Value-Based Question

• The planet earth while rotating is also revolving around the sun in an elliptical orbit in a year.

Question 1.
What would happen if it stops moving?
If the earth stops moving, the portion before the sun would have remained the same and continued to experience day regularly. On the other hand, the portion of the earth away from the sun would have experienced night continuously. Hence, life would have not been possible on earth in such a situation.

Question 2.
Why is this movement considered essential for our survival on the planet?
Due to the rotation of the earth, the half portion of the earth facing the sun experiences day, and thus warmth in the region. At the same time, the other half experiences dark and cold as well. Also the revolution of the earth causes seasons. Hence, due to the earth’s movement (rota-tion and revolution), it contains favourable environmental conditions for the survival of all forms of life.

Something To Do

Question 1.
Find out the duration of day and night on the following days with the help of sunrise and sunset timings.
(a) 21st March
(b) 21st June
(c) 23rd September
(d) 22nd December

 Days Duration of Day Duration of Night (a) 21st March 12 hours 12 hours (b) 21st June 15 hours 9 hours (c) 23rd September 12 hours 12 hours (d) 22nd December 9 hours 15 hours

Question 2.
Make a chart to be displayed in your classroom showing the revolution of the earth and the seasons.
Do yourself.

Question 3.
Write your observations and then discuss in class.
Do yourself.

### DAV Class 6 Social Science Chapter 4 Question Answer – The Motions of the Earth (Day-Night and Seasons)

A. Tick (✓) the correct option.

Question 1.
The earth completes one rotation on its axis in
(a) 12 hours
(b) 15 hours
(c) 24 hours
(d) 36 hours
(c) 24 hours

Question 2.
The earth completes one revolution around the sun in
(a) 365 1/4 days
(b) 366 days
(c) 3661/4 days
(d) 390 days
(a) 365% days

Question 3.
Direct rays of the sun fall on the equator on
(a) 21st June
(b) 21st March
(c) 23rd September
(d) 22nd December
(b) 21st March

Question 4.
The cycle of seasons occurs due to the earth’s
(a) gravitation
(b) rotation
(c) revolution
(d) none of these
(c) revolution

Question 5.
A leap year has
(a) 365 days
(b) 366 days
(c) 370 days
(d) 390 days
(b) 366 days

Question 6.
The minimum distance between the Earth and the sun is on
(a) 4th July
(b) 23rd September
(c) 3rd January
(d) 22nd December
(c) 3rd January

B. Very Short Answer Type Questions

Question 1.
What is meant by the earth’s axis? Define.
The earth’s axis is an imaginary straight line that joins the two poles of the earth and on which the earth rotates. The axis of the earth is not perpendicular but tilted to one side.

Question 2.
What is the tilt of the axis of the earth called?
It is known as the inclination of the earth’s axis.

Question 3.
What is the angle of inclination of the earth’s axis with its orbital plane?
The angle of inclination of the earth’s axis with its orbital plane is 66Y20.

Question 4.
When is the distance maximum between the earth and the sun?
The distance between the earth and the sun is maximum on 4th July.

Question 5.
Name the direction in which the earth revolves round the sun.
From west to east.

Question 6.
Name two motions of the earth.
Rotation and revolution.

Question 7.
Why do seasons keep on changing?
Seasons keep on changing due to the change in the position of the earth around the sun.

Question 8.
Which two factors are responsible for causing the cycle of seasons on the earth?
The two factors responsible for causing the cycle of seasons on the earth are—(z) the revolution of the earth and (ii) the inclination of the earth’s axis.

Question 9.
Name the season the Northern Hemisphere enjoys on 23rd September.
Autumn.

Question 10.
When do the longest day and the shortest night occur in the Northern Hemisphere?
In the Northern Hemisphere, the longest day and the shortest night occur on 21st June.

Question 11.
Write the name of the place that is nearest to the equator and also one that is farthest from the equator.

• The place nearest to the equator – Kourou in French Guina.
• The place farthest to the equator – Helsinki in Finland.

C. Short Answer Type Questions

Question 1.
What would happen if the earth stops rotating?
If the earth stops rotating the portion of the earth facing the sun would always experience day and thus there would be continuous warmth in the region. At the same time, the other half would always remain dark and be freezing cold all the time. In both situations, life would be miserable. Thus, there would no exaggeration if we say that life would be impossible if the earth stops rotating.

Question 2.
What seasons do you observe in Northern and Southern Hemispheres on 21 st June? Why?
On 21st June, the Northern Hemisphere in inclined towards the sun. The rays of the sun fall vertical on the Tropic of Cancer. The larger portion of the Northern Hemisphere faces the sun. As a result, this hemisphere receives more heat and therefore it is summer season here. The situation in the Southern Hemisphere is just the opposite. The sunrays are more slanting and, therefore, it is winter season in this hemisphere.

D. Long Answer Type Questions

Question 1.
Explain the occurrence of different seasons on the earth.
or
Why do we have varying length of day and night?