By reviewing Kerala Syllabus Class 8 Social Science Notes Kerala Syllabus Chapter 3 Movements of the Earth: Rotation and Revolution Important Questions, students can improve their conceptual understanding.
Movements of the Earth: Rotation and Revolution Extra Questions and Answers Class 8 Social Science Chapter 3 Kerala Syllabus
Movements of the Earth: Rotation and Revolution Class 8 Important Questions
Question 1.
What is the direction of Earth’s rotation?
a. From east to west
b. From west to east
c. From north to south
d. From south to north
Answer:
b. From west to east
Question 2.
What is the name of the imaginary line that separates night and day on Earth?
a. Circle of illumination
b. Line of Latitude
c. Line of Longitude
d. Equator
Answer:
a. Circle of illumination
Question 3.
What is the name of the phenomenon when the Earth comes closest to the Sun?
a. Eclipse
b. Perihelion
c. Solstice
d. Equinox
Answer:
b. perihelion
Question 4.
What is a year with 366 days called?
a. Equinox
b. Common year
c. Leap year
d. Solar year
Answer:
c. Leap year
Question 5.
Ferrel’s law is related to which effect?
a. Gravitational effect
b. Coriolis effect
c. Doppler effect
d. Heating effect
Answer:
b. Coriolis effect
Question 6.
Greenwich Mean Time is calculated based on which longitude?
a. 90° East
b. 180° longitude
c. 0° longitude
d. 23.5° North
Answer:
c. 0° longitude
Question 7.
What is the approximate tilt of the Earth’s axis?
a. 0°
b. 90°
c. 66.5°
d. 23.5°
Answer:
d. 23.5°
Question 8.
On which day is the spring equinox?
a. March 21
b. December 22
c. June 21
d. September 23
Answer:
a. March 21
Question 9.
In which month does perihelion usually occur?
a. June
b. December
c. January
d. July
Answer:
c. January
Question 10.
Which day is the Winter Solstice?
a. March 21
b. June 21
c. September 23
d. December 22
Answer:
d. December 22
Question 11.
How far ahead is Indian Standard Time (IST) from Greenwich Mean Time?
a. 5 hours
b. 5 hours 30 minutes
c. 6 hours
d. 4 hours 30 minutes
Answer:
b. 5 hours 30 minutes
Question 12.
How long does it take for the Earth to rotate 1° in longitude?
a. 1 minute
b. 4 minutes
c. 15 minutes
d. 60 minutes
Answer:
b. 4 minutes
Question 13.
What are the main effects of the Earth’s rotation?
a. Snowfall and drought
b. Earthquakes and volcanic eruptions
c. Day and night, and the Coriolis effect
d. Seasons and weather changes
Answer:
c. Day and night, and the Coriolis effect
Question 14.
Match the following
| Season | Characteristics |
| 1. Spring | a. High ambient temperature. |
| 2. Summer | b. Low ambient temperature. |
| 3. Autumn | c. Plants bloom and bear fruit. |
| 4. Winter | d. Trees shed their leaves. |
a. 1 – a, 2 – b, 3 – c, 4 – d
b. 1 – b, 2 – a, 3 – d, 4 – c
c. 1 – c, 2 – a, 3 – d, 4 – b
d. 1 – d, 2 – c, 3 – b, 4 – a
Answer:
c. 1 – c, 2 – a, 3 – d, 4 – b
| Season | Characteristics |
| 1. Spring | c. Plants bloom and bear fruit. |
| 2. Summer | a. High ambient temperature. |
| 3. Autumn | d. Trees shed their leaves. |
| 4. Winter | b. Low ambient temperature. |
Question 15.
What are the main effects of the Earth’s rotation?
Answer:
The Earth’s rotation causes day and night. It also causes the Coriolis effect, which causes objects moving freely on the Earth’s surface to deviate in direction due to rotation.
Question 16.
How long does it take the Earth to complete one orbit? How does this cause a leap year?
Answer:
It takes the Earth 365 1/4 days (365 days and 6 hours) to complete one orbit. Every four years, the extra quarter day (6 hours × 4 years = 24 hours or 1 day) is added to make the month of February 29 days. Such years are called leap years.
Question 17.
What is Perihelion? In which month does it occur?
Answer:
Perihelion is the phenomenon when the Earth comes closest to the Sun. At this time, the approximate distance between the Earth and the Sun is 147 million kilometers. It generally occurs in the month of January (specifically January 3).
Question 18.
What are the equinoxes? On which days do they occur?
Answer:
Equinoxes or the days of the equinoxes are the days when the length of night and day is equal in both hemispheres (Northern Hemisphere and Southern Hemisphere). This occurs on March 21 (Spring Equinox) and September 23 (Autumn Equinox) when the sun’s rays fall perpendicularly on the equator.
Question 19.
What is Uttarayanam?
Answer:
Uttarayanam is the phenomenon in which the relative position of the Sun moves from the southern hemisphere to the northern hemisphere due to the tilt of the Earth’s axis. It occurs approximately from December 22 to June 21.
Question 20.
What day is the summer solstice? What is an important feature of this day?
Answer:
The summer solstice is on June 21. On this day, the sun’s rays fall perpendicularly on the equator (23.5° North), so the Northern Hemisphere experiences the longest day and the shortest night.
Question 21.
What were the two main things used in ancient times to determine local time?
Answer:
In ancient times, two main things were used to determine the local time at a location: the position of the sun, or the time when the sun reaches its zenith, and the length of the shadow.
Question 22.
What is an aurora? Where can it be seen?
Answer:
An aurora is a natural, colourful light in the atmosphere that occurs during the winter months when strong solar winds occur in the polar regions. It is usually seen in the high latitudes of the polar regions.
Question 23.
How many days does it take for the Sun So complete one rotation on its axis?
Answer:
The Sun takes approximately 27 days to complete one rotation on its axis.
Question 24.
What is an aphelion? in which month does it occur?
Answer:
Aphelion is the phenomenon when the distance between the Sun and the Earth is the greatest. It occurs at a distance of about 152 million kilometers, it generally occurs in the month of July (especially July 4)
Question 25.
What is rotation? What are the two main changes that result from it?
Answer:
Rotation is the rotation of the Earth on its axis. This results in day and night. When one side of the Earth receives sunlight, it is day, and when the other side is in darkness, it is night. Another result is the Coriolis effect; the rotation causes winds and ocean currents that move freely on the Earth’s surface to change direction.
Question 26.
What is the Coriolis effect? How does it affect the direction of winds and ocean currents?
Answer:
The Coriolis effect is a phenomenon in which objects moving freely on the Earth’s surface are deflected by the Earth’s rotation. As a result, according to Ferrel’s law, the direction of wind and ocean currents is deflected to the right of their direction of travel in the Northern Hemisphere and to the left in the Southern Hemisphere. The force that causes this is called the Coriolis force.
Question 27.
How do leap years occur?
Answer:
It takes the Earth 365 days and about 6 hours (1/4 day) to orbit the Sun once. These extra 6 hours each year are not included in the calendar. Every four years, these extra 6 hours become a full day (6 hours × 4 = 24 hours). This extra day is added to the month of February, and that year is considered a leap year with 366 days.
Question 28.
What is Apparent Movement of the Sun? What is its effect?
Answer:
Apparent Movement of the Sun is the phenomenon in which the relative position of the Sun appears to move northward and southward between the lines of North and South as the Earth’s axial tilt (23.5°) remains constant throughout its orbit. This is not actually the movement of the Sun, but the tilt and rotation of the Earth that cause this relative movement. The main result bf this is the difference in the length of days and nights experienced in each region. In addition, it also causes the seasons.
Question 29.
When is the summer solstice? What is special about this day in the Northern Hemisphere?
Answer:
The summer solstice is on June 21. On this day, the sun’s rays fall perpendicularly on the northern hemisphere (23.5° North). Therefore, the Northern Hemisphere experiences the longest day and the shortest night on this day. It is generally summer in the Northern Hemisphere at this time.
Question 30.
When is the winter solstice? What is special about this day in the Southern Hemisphere?
Answer:
The winter solstice is on December 22. On this day, the sun’s rays fall perpendicularly on the southern hemisphere (23.5° South). Therefore, the Southern Hemisphere experiences the longest day and the shortest night on this day. During this time, it is generally summer in the Southern Hemisphere.
Question 31.
How is Indian Standard Time (IST) determined?
Answer:
Standard time is determined to avoid time differences within a country and to reduce time confusion. In India, the 82.5° East longitude has been chosen as the Standard Time of India. The local time at this longitude is considered as Indian Standard Time. This longitude is 5 hours and 30 minutes ahead of Greenwich Mean Time (82.5° × 4 minutes/degree = 330 minutes = 5 hours and 30 minutes).
Question 32.
What are Time Zones? What is their importance?
Answer:
Time zones are the divisions of the world into 24 time zones with a time difference of approximately one hour. Each time zone has an area of approximately 15° of longitude (15° × 4 minutes/degree = 60 minutes = 1 hour). These time zones help to standardise timekeeping around the world and avoid time confusion in communication and transportation between different countries. Larger countries may have more than one time zone.
Question 33.
What are the traditional seasons in India? How many are there?
Answer:
India traditionally has six major seasons.
- Vasantham – March, April
- Greeshmam – May, June
- Varsham – July, August
- Sarath – September, October
- Hemantham – November, December
- Sisiram – January, February
Question 34.
Explain the main differences between the rotation and revolution of the Earth.
Answer:
Rotation is the spinning of the Earth on its imaginary axis. The direction of rotation of the Earth is from west to east. The two effects of rotation were day and night, and the Coriolis effect. The time taken for the Earth to complete one rotation is 24 hours (23 hours 56 minutes 4 seconds). The Earth receives light from the Sun. During rotation, the part of the Earth facing the Sun has daytime and the other part experiences night. The imaginary line that demarcates day and night on the Earth is called the Circle of Illumination. While rotating on its axis, the Earth revolves around the Sun in a fixed orbit. This is known as Revolution. The time taken to complete one revolution in the elliptical orbit is 365 days. 365 days is considered as one year for practical convenience. The fraction of 14 days is added once in 4 years to February, making it 29 days. Thus, a year with 366 days is called a leap year.
Question 35.
Explain how the relative position of the Sun affects the length of day and night.
Answer:
The Earth is tilted about 23.5° on its axis, which remains constant as the Earth orbits the Sun. Due to this tilt, the Sun’s relative position is felt to move northward and southward between the lines of the Northern and Southern Hemispheres. This is called precession. As the Sun’s relative position changes, the amount of sunlight received by each part of the Earth varies. For example, on June 21, the Northern Hemisphere experiences its longest day because the Sun’s rays fall perpendicularly. Similarly, on December 22, the Southern Hemisphere experiences its longest day. On March 21 and September 23, the Sun’s rays fall perpendicularly on the Equator, so the length of day and night is equal all over the world.
Question 36.
Explain the reasons for the occurrence of seasons.
Answer:
There are three main reasons for the occurrence of seasons on Earth:
Revolution: One of the main reasons is that the Earth revolves around the Sun in its elliptical orbit. The Earth revolves around the Sun once in a year.
Fluctuations in solar energy availability: The amount of solar energy received by each region varies during the Earth’s orbit. Areas where the sun’s rays fall vertically are warmer, and areas where they fall obliquely are cooler.
Earth’s axial tilt: The Earth’s axis is tilted at an angle of about 23.5° to its orbit. This tilt remains constant throughout the orbit. Together, these three factors change the relative position of the Sun and cause each region to experience unique weather conditions (seasons).
Question 37.
What is the need to determine standard time in a country?
Answer:
The main requirements for determining standard time in a country are as follows:
Time unification: There may be differences in local time at different places within the country. A unified time is necessary to avoid this confusion.
General activities: Railway timing, radio and television broadcasting, public. examinations, industrial and commercial activities all take place across the country based on a standard time.
To avoid confusion: When there are multiple time zones within a country, there may be time confusion for travellers and communicators. A standard time helps to avoid this.
Efficient administration: A unified time is essential for the efficient implementation of administrative, economic and social matters.
Question 38.
Why has only one standard time been adopted for India in general, despite the difference in local time between the eastern and western parts of India of about two hours?
Answer:
The longitude of the eastern and western parts of India is about 30° (i.e., a time difference of about 2 hours). However, a uniform time is essential to avoid time confusion and ensure efficiency in railway transport, radio broadcasting, public examinations, and day-to-day industrial and commercial activities within the country. If two or more time zones existed, there would have been major problems and confusion in timekeeping among different states. Therefore, to ensure general efficiency and smooth functioning, a single standard time has been adopted by selecting 82.5° East longitude as the standard longitude of India.
Question 39.
What is the Aurora? How does it happen? How is it known in the North and South Poles?
Answer:
The aurora is a natural colourful light show that occurs in the atmosphere of the polar regions, especially in winter, when strong solar winds (energetic particles from the Sun) collide with the Earth’s magnetosphere. It is a beautiful phenomenon that can be seen at high latitudes. When charged particles from the Sun interact with the Earth’s magnetosphere, these particles are attracted to the Earth’s magnetic poles in the polar regions. When these particles collide with gas molecules (oxygen and nitrogen) in the Earth’s atmosphere, they become energised and release that energy as light. Because each gas emits light at its own wavelength, different colored images (green, pink, red, blue, and violet) can be seen in the aurora. Names: In the North Pole, it is called the ‘Aurora Borealis’ or ‘Northern Lights’, and in the South Pole, it is called the ‘Aurora Australis’ or ‘Southern Lights’.
Question 40.
What is the time difference between Greenwich Mean Time and Indian Standard Time? Explain how it is calculated.
Answer:
Time difference: The time difference between Greenwich Mean Time and Indian Standard Time (IST) is 5 hours and 30 minutes. That is, when it is 12 noon in Greenwich, it is 5:30 pm in India. Greenwich Mean Time: The Greenwich Meridian is the 0° longitude line, which passes through Greenwich, England. It is used as a reference point to determine the time in other places in the world.
Indian Standard Time: The standard longitude of India is the 82.5° east longitude line. It passes through the center of India. Method of calculation: It takes 4 minutes for the Earth to rotate one degree on its axis. For every degree of longitude east of Greenwich Mean Time, 4 minutes are added. Since India’s standard longitude is 82.5° East, to calculate the time difference, we multiply 82.5° by 4 minutes: 82.5 × 4 minutes = 330 minutes. Converting these 330 minutes to hours gives us 5 hours and 30 minutes (330 / 60 = 5.30 hours). Thus, India’s time is 5 hours and 30 minutes ahead of Greenwich Mean Time.
Question 41.
How do the rotation and revolution of the Earth affect human life? Explain with examples.
Answer:
The rotation and revolution of the Earth greatly affect human daily life, culture and economic activities: Rotation – Day and Night: The rotation of the Earth causes day and night. This controls human sleep patterns, working hours and daily activities. For example, human’s are accustomed to working during the day and resting at night. Agriculture, travel, etc., all depend on day and night. Rotation plays an important role in determining local time. Time varies depending on the position of the sun at each location, which serves as the basis for time zones and standard times around the world.
Revolution – Seasons: The Earth’s rotation causes the change of seasons. This affects agriculture, clothing, festivals and lifestyle. For example, farmers plant some crops in summer and other-crops in winter. People wear clothes according to the weather.
Orbit – Length of days and nights: Due to the rotation of the Earth, the length of days and nights varies at different times of the year. This affects human energy consumption and working hours. For example, in summer, the days are longer, so it is possible to work outside for longer.
Socio – cultural influence: Seasonal festivals (for example, Onam, Vishu, Christmas), celebrations, and recreational activities are all shaped by the movements of the Earth. This is an integral part of human social life.