Center of the earth

[kermit911]

How is the center of the earth still hot? Wouldn't have cooled down by now? Example: You have a 10 ft. steel ball that you heat up to 1000 degrees. Now when you stop heating it up, it cools down. Might take awhile but it does.

thanx

[red7]

some say the earth is hollow!

[red7]

http://en.wikipedia.org/wiki/Hollow_Earth
check it out

[bernardo]

It's so big that it takes ages to cool down. four billion years ago it was still really hot on the outside as well, like Venus is now. It's also being heated up a bit because of the tidal friction forces from the Sun and Moon. But basically it is taking so long to cool down because it's so big.

[Lil' help]

In short - Radioactive reactions occur within the earths mantle producing heat. =)

[brachiopod]

(sorry for multi-part posting - put it fails otherwise.....)</>

You did not say whether your 10 ft steel ball has radioative decay occurring within it, or whether the decay particles are absorbed by the 10 ft steel ball's mass, causing the kinetic energy to be converted into heat energy and held within the core.

Nor did you say whether the net heat gain due to radioactive decay during the intial period after the 10ft steel ball's formation was greater than the sum conductive and radiational loss to its surroundings
.

[brachiopod]

Also, you didn't say whether your 10 ft steel ball was also was being bombarded by smaller steel balls, each of which would add a small, net sum of energy to the main body as the kinetic energy is converted (ultimately) to heat energy. (The larger proportion of this 'imparted accretionary energy' is, of course radiated back into the space surrounding the 10 ft steel ball.)

However, if they occur, these small additions to the 10 ft steel ball's heat energy, even if they do not exceed the total heat loss from the 10 ft steel ball, would at least cause the 10 ft steel ball to cool down a lot slower than would be expected if no heat energy additions at all were made to the system.