a)Name the first two planets of the solar system. (b)Explain the origin of the earth according to the Nebula Cloud Theory. (c)Give two reasons why the earth...

      

a)Name the first two planets of the solar system.

b)Explain the origin of the earth according to the Nebula Cloud Theory.

c)Give two reasons why the earth has a spherical shape

d)State four effects of the rotation of the earth on its axis.

e)Describe the structure of the earth's crust

  

Answers


Davis
a)Mercury
- Venus

b)-The explosion of the stars led to the formation of a huge cloud of gases
(hydrogen and helium), dust and ice particles.
- This cloud whirled, cooled and condensed to a disc shape.
- The gravitational attraction within the materials increased cause the particles to
compact. Some particles broke from the edge of the disc and whirled.
- The compacted particles swirled faster towards the centre of the disc in different
directions. As they whirled they cooled or solidified to form the planets.
- This swirling caused particles to collide losing a little energy at a time.
- The middle of the spinning disc condensed to form the sun while the material
spinning around condensed into large chunks of materials called planetoids.
- The planetoids collided and coalesced into large bodies called planets.
- The earth is one of the planets.
- The centre of the disc formed the sun.

c)-The earth experiences the force of gravity pulling towards the centre which
creates a rounding effect on its shape.
- The North and South poles experience centripetal force which constantly pull
towards each other causing the flattening at the poles.
- At the equator the earth experiences the centrifugal force which causes the
bulge.

d)It causes the occurrence of day and night /apparent movement of the sun from
East to West.
- It causes difference in time between places over the earth's surface.
- It causes deflection of winds / ocean currents.
- It causes differences in atmospheric pressure on the surface of the earth.
- It causes ocean/sea tides

e)It is divided into two layers - sial (continental crust) and sima (oceanic crust).
- The sial rests on the sima
- The sial contains mainly silica and aluminium.
- The sima contains silica, magnesium and iron.
- The sial is lighter/has a density of 2.65 to 2.70 gm per cc.
- The sial has mainly granitic rocks.
- The sima has basaltic rocks.
- The sima is heavier/has a density of 2.7 to 3.0 g/cc
- The sima is fairly flexible
-It's rocks are generally brittle/solid.
- The earth's crust extends between 6 to 80 km
Githiari answered the question on September 15, 2017 at 04:00


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