10 Important Scientific Reasons & Explanations

10 Important Scientific Reasons & Explanations 

1) The Earth bulges out at equator. Why?

Ans: This is due to the shape of the earth. The earth is not a true sphere but it is an ellipsoid. The equatorial diameter of the earth is 12756.27 kms. While its polar diameter is 12713.505 km. the difference between its equatorial and polar diameter is about 43 kilometres. The rotation of the earth on its axis produces a centrifugal force which increases its equatorial diameter. That is why earth bulges at the equator.

2) The Sun appears red at sunset and sunrise. Why?

Ans: The sun appears red at the time of sunset and sunrise due to the scattering of light by small particles of dust or smoke near the surface of the earth. The light travels relatively without hindrance that is why the sun appears red at the time of sunset and sunrise.

3) The ozone layer in the atmosphere is necessary for our survival. Why?

Ans: ozone layer in the atmosphere is very necessary for plant and animal survival because it is the absorber of ultraviolet rays which are very dangerous for animal health. Ultraviolet rays cause cancer of skin, spotting of plants etc. that is why the ozone layer is necessary and essential for animal as well as plant survival.

4) The sky from moon appears black. Why?

Ans: as the moon has no atmosphere, so the sky looks completely black when viewed from the moon.

5) Roads are bent inwards on curves. Why?

Ans: The roads are bent inwards on the curves and at the turns because the bents avoid falling outside and prevent the accidents.

OR

When an object turns in a circle it is influenced by a centrifugal force which pushes it away from the centre of the circle. When vehicles turn on a road they fall outside under the influence of centrifugal force. In this way there is danger of falling or slipping out of road at a turn. Roads are made in a way that these bent inward at the turns to avoid falling outside and to prevent accidents.

6) Australian continent has winter season when we have summer season in Pakistan.

Ans: the earth on its axis is not at a vertical angle to its orbit. It is inclined at an angle of about.

In this way when the northern hemisphere of the earth is inclined to the sun and getting direct sun rays, southern hemisphere is inclined away from the sun and getting less direct rays. Thus the northern hemisphere has summer season and southern hemisphere has winter season.

Pakistan is in the northern hemisphere while Australia is in the southern hemisphere. So when

there is winter in Australia there is summer season in Pakistan.

7) Meat takes longer to cook on mountains.

Ans: The meat takes longer time to cook on the mountains because the atmospheric pressure decreases with attitude and the boiling point of a liquid is directly proportional to the atmospheric pressure.

8) Water remains cool in earthen pitcher.

Ans: This occurs due to the process of evaporation. Water gets cooled on evaporation. As the earthenware pitcher is concerned, they have small pores. Water tends to come out of pores and evaporates which results in cooling effect on the earthenware and water.

While in the metal pots there are no pores and evaporation does not take place. Besides metal has tendency to absorb heat that why water does not get cooled in a metal pot.

9) Ice and salt mixture is used as a freezing agent by manual ice-cream makers.

Ans: In manual ice-cream making a mixture of salt and ice is always used because salt has capacity to reduce the temperature of ice by decreasing its freezing point. That’s why ice and salt mixture is used as freezing agent in manual ice cream making.

10) It is not advisable to sleep under trees during the night.

Ans: During night the plants release carbon dioxide (CO2) which is a poisonous gas and injurious to health. That is why it is not advisable to sleep under trees during night.