change into passive voice We must listen to his words.
Answers
His song must be listened to by us is the passive voice.
Unless there is a good reason for using it, the sentence is changed to passive voice only.
It must taken to listen and thus deliver awesome results after changing into the direct and indirect form.
24Rotation and Revolution
I. Short Answer Questions.
Question 1.
What is meant by the earth’s axis?
Answer:
The earth’s axis is the imaginary line joining the North Pole to South Pole, around which the earth rotates.
Question 2.
Name the two chief motions of the earth.
Answer:
Two chief motions of the earth are rotation and revolution.
Question 3.
Describe two characteristics of rotation.
Answer:
Two characteristics of rotation are the complete rotation of the earth from west to east in 24 hours and along its tilted axis which is always in the same direction towards the Pole Star.
Question 4.
Mention two effects of the rotation of the earth.
Answer:
Day and night are caused by the rotation and the creation of centrifugal force resulting in a bulge in the equatorial part and flattened top at the poles.
Question 5.
Mention any two possible consequences if the axis of the earth was vertical instead of inclined.
Answer:
1. Then at all places on the earth, lengths of day and night would have been equal, i.e. 12 hr of day and 12 hr of night
2. There would have been no seasons.
Question 6.
State one reason why we do not feel the motions of the earth.
Answer:
According to the gravitational force everything is attached to the earth, keeping everything at rest at their original position, unless any external force compels to motivate it.
Question 7.
Define ‘revolution’.
Answer:
Revolution is the revolving of the earth on its orbit around the sun in 365 days and 6 hours nearly.
Question 8.
State two chief characteristics of the revolution of the earth.
Answer:
The earth revolves at an average speed of 100,000 km per hour. The earth revolves in an elliptical orbit with two particular positions i.e. perihelion 147.3 million km away from sun in January and aphelion 152 million km away from sun in July.
Question 9.
Mention two effects of revolution.
Answer:
Two main effects of revolution are the seasonal changes throughout the year and the creation of particular heat zones on temperature zones.
Question 10.
What is meant by Summer Solstice? When do we have Summer Solstice in the Northern Hemisphere?
Answer:
Summer Solstice occurs on June 21, in the Northern Hemisphere, when the sun is overhead at the Tropic of Cancer and the North Pole is tilted towards the sun, so the summer season is experienced in the Northern Hemisphere.
Question 11.
What is meant by Equinox? Give the dates of the two Equinoxes.
Answer:
Equinox means the time when the days and nights are equal all over the world. The particular dates of equinoxes are 21st March (Spring or Vernal Equinox) and 23rd September (Autumnal Equinox).
Question 12.
What will be the duration of daylight in the Northern Hemisphere on March 21st at 23°30′ latitude?
Answer:
The duration of daylight will be of 12 hours.
Question 13.
What is the relationship of seasons between the Northern and Southern Hemispheres?
Answer:
The seasonal episodes are reciprocal with each other i.e. if Northern Hemisphere experiences summer season, then Southern Hemisphere has winter season; in the same way if there is spring season in Northern Hemisphere, there is autumn season in Southern Hemisphere and vice-versa.
Question 14.
How has the phenomenon of the ‘Midnight Sun’ come about ?
Answer:
Beyond the Arctic Circle, the regions experience 24 hours daylight in summer season due to the North Pole facing continuously towards the pole. It is called the ‘Midnight Sun’. Norway is called land of Midnight Sun.
Question 15.
What are the seasons in the Northern and the Southern Hemispheres on 23rd September?
Answer:
There are Autumn season and spring season in the Northern and Southern Hemispheres on 23rd September, respectively.
Question 16.
Mention one effect of seasons in low and high latitudes.
Answer:
The effect of seasons in low and high latitudes is distinct through various phases of different seasons. Low latitude areas get ample temperature and rainfall while the high latitude areas are cold and receive less rainfall. Tropical regions are always warm with heavy rainfall season, while the temperate and polar regions are cold with scanty rainfall, while the polar regions are always covered with perpetual snow due to the temperature below 0°C.
II. Give reasons for each of the following
Question 1.
We always see the sun rising in the East.
Answer:
As the earth moves from West to East, the .