Chapter-3 Motions Of The Earth
1. Answer the following questions briefly.
Question a:- What is the angle of inclination of the Earth’s axis with its orbital plane?
Answer :- The plane formed by the orbit is known as the orbital plane. The axis of Earth which is an imaginary line marks an angle of 66 1/2° with its orbital plane
Question b:- Define rotation and revolution.
Answer:- The Daily motion of the earth, the earth takes 24 hours to complete one rotation around its axis. The second of the earth around the sun in its orbital is called revolution it takes 365 1/4 days to complete one revolution
Question c:- What is a leap year?
Answer:– Every 4th-year February is 29 days instead of 28 days such a year with 366 days is called leap year, six hours save will be added to make a day.
Question d:- Differentiate between the Summer and Winter Solstice.
It is the position of the earth when the rays of the sun fall directly on the tropic of cancer In the position, the north pole is tilted towards the sun. A larger portion of the northern hemisphere gets light from the sun hence it is summer in the Northern Hemisphere During this period in the northern hemisphere, days are longer than nights
It is the position of the earth when the rays of the sun fall directly on the tropic of Capricorn In this position, the north pole is tilted away from the sun A larger portion of the southern hemisphere gets light from the sun hence it is winter in the northern hemisphere During this period in the northern hemisphere, nights are longer than days
Question e:- What is an equinox?
Answer:– It is the position of the earth where the direct rays of the sun fall on the equator at this position neither of the polls is tilted towards the sun so the earth experience equal days and nights This is called equinox
Question f:– Why does the Southern Hemisphere experience Winter and Summer Solstice in different times than that of the Northern Hemisphere?
Answer:- When the North Pole is tilted towards the Sun, the Northern Hemisphere experiences Summer Solstice. At this time, since the South Pole is tilted away from the Sun, the Southern Hemisphere experiences Winter Solstice.When the North Pole is tilted away from the Sun, the Northern Hemisphere experiences Winter Solstice. At this time, since the South Pole is tilted towards the sun, the Southern Hemisphere experiences Summer Solstice.
Question g:- Why do the Poles experience about six months day and six months night?
Answer:- The poles experience about 6 months days and six months of the night because of the tilt each pole is tilted towards and away from the sun for about six months each. When the north pole is tilted towards the sun it experiences continuous day and night for six months each. When the north pole is tilted towards the sun it experiences continuous day and night for six months it is the night for the same pole is tilted towards the sun
2: Tick the correct answers
(a) The movement of the Earth around the Sun is known as
Ans. (ii) Revolution
(b) Direct rays of the sun fall on the equator on
Ans. (i) 21 March
(iii) 22 December
(c) Christmas is celebrated in summer in
Ans. (iii) Australia
(d) Cycle of seasons is caused due to
Ans. (ii) Revolution
3: Fill in the blanks.
(a) A leap year has 366 number of days.
(b) The daily motion of the Earth is rotation .
(c) The Earth travels around the Sun in elliptical orbit.
(d) The Sun’s rays fall vertically on the Tropic of cancer on 21st June.
(e) Days are shorter during winter season