➽ The Earth bulges out at equator. Why?
Answer: 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.
➽ The Sun appears red at sunset and sunrise. Why?
Answer: 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.
➽ The ozone layer in the atmosphere is necessary for our survival. Why?
Answer: 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.
➽ The sky from moon appears black. Why?
Answer: as the moon has no atmosphere, so the sky looks completely black when viewed from the moon.
➽ Roads are bent inwards on curves. Why?
Answer: 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.
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