Chapter 2: Motions of the Earth – Exercise Solutions

1. What’s the solution?

Question: Amit wants to take his granny to Australia which is in the southern hemisphere. But she cannot bear very cold weather. When should they make this trip?

• Answer: They should plan their trip between 23 September and 22 March. During this period, the days are longer than the nights in the southern hemisphere, so it gets more heat and it is summer there.

2. Use your brain power!

Question (a): How many rotations does the earth complete during one revolution around the sun?

• Answer: The earth completes about 365 and a quarter rotations during one revolution around the sun. This is because one rotation equals one day, and one revolution takes 365 days and 6 hours.

Question (b): It is sunrise at Itanagar in Arunachal Pradesh. Write the names of the following cities in the order in which the sun will rise there. Mumbai (Maharashtra), Kolkata (West Bengal), Bhopal (Madhya Pradesh), Nagpur (Maharashtra).

• Answer: The earth rotates from west to east, meaning its different parts come into the light of the sun one after the other. Moving from east to west, the sun will rise in these cities in the following order: Kolkata, Nagpur, Bhopal, and finally Mumbai.

3. Fill in the blanks.

• (a) The motion of the earth around itself is called rotation.
• (b) The motion of the earth around the sun is called revolution.
• (c) The rotation of the earth gives rise to day and night.

4. What is meant by each of the following terms?

• (a) Full moon: On a full moon night, we see the entire side of the moon that faces the earth.
• (b) New moon: On a new moon night, we cannot see any of the moon’s surface that faces the earth.
• (c) Lunar month: The period from one new moon to the next is of about 28 to 30 days and is called the lunar month.
• (d) Tithi: Every day of the lunar month is called a tithi.

5. Answer the following questions.

Question (a): What is the equator?

• Answer: The equator is an imaginary circle drawn around the surface of the earth exactly in between the north and south poles.

Question (b): What are the two parts of the earth made by the equator?

• Answer: The two equal parts the equator makes of the earth are called the northern hemisphere and the southern hemisphere.