0

Earth has more kinetic energy than the cloud from which it was formed. Where did this energy come from?

Dale
  • 99,825
Ayat Mamin
  • 1
  • 1
    Related/possible duplicate: https://physics.stackexchange.com/q/23104/50583 – ACuriousMind Dec 24 '20 at 16:13
  • 1
    Also, what is your source for the claim that Earth has more kinetic energy than the cloud from which it formed? Please add that to your question if you can. – ACuriousMind Dec 24 '20 at 16:13

2 Answers2

2

Earth has more kinetic energy than the cloud from which it was formed .Where did this energy came from?

Earth has less gravitational potential energy than the cloud from which it was formed. The gain in kinetic energy came from the loss of gravitational potential energy. The process of gravitational collapse also increased the thermal energy of the Earth, again from the same source of energy.

Dale
  • 99,825
0

I'm not sure how you know how much kinetic energy the cloud had, but if you consider the earth alone it is not an isolated system. So energy conservation doesn't apply and as the earth was formed, the cloud was subject to gravitational forces from nearby bodies which could change the amount of energy that was in the cloud to start with. That change could include an increase in kinetic energy, depending on the balance of kinetic and gravitational potential energy.

Not_Einstein
  • 2,746
  • Conservation of KE is not a thing. Even for isolated systems the KE can change, due to internal forces. – nasu Dec 24 '20 at 16:16
  • @nasu: I edited my answer. – Not_Einstein Dec 24 '20 at 16:33
  • Energy conservation may apply. KE conservation is the one that is not a thing. You realize the difference between KE and energy, right? – nasu Dec 24 '20 at 22:07
  • Energy conservation doesn't apply if external forces do work. I said it could include an increase in k.e., which is what OP was asking about. And you realize the difference between a helpful answer and a sarcastic one, right? – Not_Einstein Dec 24 '20 at 23:20