Expert: Jayendra Upadhye - 6/9/2006

Question
Why does the Earth rotates on its own axis while revolving around the Sun? Why does not the Earth stops rotating on its own axis?  

Answer
Hi Mohit..
how old are you?
It does not stop rotating on its own axis simply because of these things:-
1 - The earth is a really huge ball of rock / iron and other heavy elements..and thus has a huge angular momentum.
2 - Unless a very large force exerts an opposite force on its periphery (torque), this angular momentum shall be conserved. [law of conservation of angular momentum].

The moon actually slows the earth down by action of ocean tides. about a second a year.
As a consequence it gains orbital speed and hence orbital hieght (4 cm approx) a year.

You wait long enough ..a few billion years ..and the earth will have slowed sown considerably.

Hope that suffices.

As to your first question about why it spins in the first place, it does so because when it formed from swirling dust when the sun was also similarly forming, the random dust velocities at two ends of the "accretion disc" determined that the ball thus formed spun around itself once in approx 24 hours.

Other planets formed in its surroundings have similar day hours..(mars).

Jayen