Chapter - 3 Motions of the Earth

EXERCISE ANSWERS

A. Choose the correct answer.

1. The sun appears to rise in the east because the Earth rotates on its axis from:

a. East to west
b. West to east
c. North to south
d. South to north

Ans. b. west to east

2. On leap years, the extra day is added to the month of:
a. January
b. February
c. March
d. April
Ans. b. February

3. On June 21, the Sun’s rays falls directly on the:
a. Equator

b. Tropic of cancer

c. Tropic of Capricorn
d. Antarctic Circle
Ans. b. Tropic of Cancer
 

3. On the equinoxes,
a. The Sun’s rays fall directly on the Equator
b. The North Pole is inclined towards the Sun
c. The Sun’s rays fall directly over the Tropic of Capricorn
d. The Sun’s rays fall directly over the Tropic of Cancer
Ans. a. the Sun’s rays fall directly on the Equator

B. Fill in the blanks.

a. The spinning of the Earth on its own axis is called _______.
Ans. Rotation

b. The Earth’s orbit is ______ in shape.
Ans. elliptical

c. The Earth takes exactly _______ days to complete one revolution.
Ans. 365 1⁄4 days

d. A leap year has _____ days.
Ans. 366

e. When it is summer in the Northern Hemisphere, it is ______ in the Southern Hemisphere.
Ans. winter

C. Mark the following sentences as True or False.

1. The Earth takes one hour to complete one rotation.
Ans. False

2. The rotation of the Earth causes day and night.
Ans. True

3. The axis of the Earth is inclined at an angle of 22 1⁄4 degrees to its orbit.
Ans. False

4. Seasons are caused due to the revolution of the Earth.
Ans. True

5. All parts of the world have equal length of days and nights throughout the year.
Ans. False

D. Answer in one or two sentences.

1. Which are the two main motions of the Earth?
Ans. The two main motions of the Earth are Rotation and Revolution.

2. What are the main effects of the rotation of the Earth?
Ans. Some of the main results of rotation are the occurrence of day and night, the apparent rising and setting of celestial objects in the sky when viewed from the Earth, and their apparent westward movement across the sky.

3. What is the Circle of Illumination?
Ans. The two sides are separated by an imaginary line that runs vertically across the globe, known as the Circle of Illumination.

4. Define revolution of the Earth.
Ans. The movement of the Earth around the Sun, along its orbit, is called revolution. The Earth takes 365 1⁄4 days (365 days and 6 hours) to complete one revolution.

5. When do the Solstices and Equinoxes occur?
Ans. On 21 March and on 23 September Equinoxes occur and on 21 June Summer Solstices and on 22 December Winter Solstices occur.

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