Why lava are hot?

Question

Why lava are hot? How they gain the energy? Will the centre of earth lose energy and become cooler after a long time?

Answer 1

Lava is hot because of the heat generated by radioactive decay. .For this heat to be able to escape at all, there has to be a temperature gradient for it to flow down. Roughly speaking, the hotter you go the deeper, which is why it is hot down a coal mine.

The earth was hot and molten to start with, because of the gravitational energy converted to heat during the process of accretion. Lord Kelvin tried to calculate how old it is from how long it would take it to lose enough heat to solidify the present crust. He came up with an answer of a few tens of millions of years. Nothing wrong with this calculation, except that he didn't know about the additional energy input.

Rutherford and his research group dated Cambrian rocks at about 550 million years old. Rutherford was giving a lecture on this, when he saw Kelvin, by then an old man, in the audience. So he went out of his way to say that his result was not consistent with Kelvin's calculation, unless some source of energy were present which Kelvin had not taken into account. "And believe me [Rutherford says in his memoirs] the old boy positively beamed."

Yes, the centre of the earth would become cool after a very long time, but the time is so long that the earth will have been swallowed up long before then by the Sun in its red giant phase.

Answer 2

The Center of the earth will loose it's heat...in the same way that the sun will burn itself out at some point it the future.

Meanwhile, Lava get's its energy from the heat which is trapped at the earth's core.

And it's hot because the energy it gains from the earth's core is Kinetic and Heat energy...which it doesn't convert...

Well...That's what I think...lol

Amber
xx

Answer 3

Lava is molten rock from deep within the earth.

After lava cools, it becomes rock,

Cheers.