1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Energy CAN be made

  1. Apr 6, 2008 #1
    Many things have an infinite source of energy, where it isn't CONVERTED from other forms of energy, nor mass. Namely, gravity. Gravity pulls. Thus, it is kinetic energy. This kinetic energy comes from nowhere. Say two objects in space were coming towards eachother because of gravity. Two rocks in space. These rocks now have potential energy to cause heat. This potential energy has come from gravity, which comes from absoulutly nothing.
  2. jcsd
  3. Apr 6, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Does gravitational potential energy mean nothing to you?

  4. Apr 6, 2008 #3
    Gravity comes from mass.
  5. Apr 6, 2008 #4
    But it's not the creation of new energy. The heat generated is the conversion of potential energy to kinetic, not the creation of new energy that didn't exist before. When you move the two object back apart again, you're converting the kinetic energy back into potential energy. The net amount of energy in the universe stays the same.
  6. Apr 6, 2008 #5
    it is just two forms of energy interchanging
    PE <-> KE
    if energy could be created, the oil price would drop and thus saved my pocket. haha
  7. Apr 6, 2008 #6
    The thing you have to remember for any simple/practical application to get energy from a object falling under gravity you first have to give it that energy by lifting it up. Thus no net energy is created.
  8. Apr 7, 2008 #7
    At Lewiston, New York they do a real nice thing. During the night when power usage is low, they pump water from the Niagara River uphill and put it into a reservoir, then during the day they allow it to flow down to the generators.
  9. Apr 7, 2008 #8
  10. Apr 7, 2008 #9
    Sure, there are quite a few stations of this nature around the world to cope with spikes in demand.
  11. Apr 7, 2008 #10
    what is the point in doing so?
  12. Apr 7, 2008 #11
    When the generating capacity of the network is more than demand then the extra energy is 'stored' by pumping the water up the hill. Then when there is more demand than capacity the water can be released providing a quick way of generating more electricity and meeting demand.
  13. Apr 8, 2008 #12
    Well, then, doesn't that mean anything that has mass has PE?
  14. Apr 8, 2008 #13
    That seems like an incredible waste of energy since it will take more energy to lift the water up the fall that can be recovered from the falling water itself (due to inefficiencis in pumping the water up the fall). Even if there is no loss then its still a waste of time since nothing would be gained by this. I find it very hard to believe that this is actually true. Its not as if the Niagra will run low if the water isn't pumper uphill again .... or does it??? Do you have a reference which states this so that I may look it up myself? Thanks.

  15. Apr 8, 2008 #14
    No. E.g. a photon moving in an inertial frame of reference has (inertial aka relativistic) mass but has zero potential energy. An electron moving in the absense of an EM field has mass and yet has no potential energy. Some objects like the nucleus of most atoms has potential energy which results from the mutual interations of the protons and neutrons inside the nuclues and that contributes to the mass of the nucleus. In fact that is where the nuclear energy can be said to reside (although I myself prefer not to think of energy as being located anywhere).

  16. Apr 9, 2008 #15


    User Avatar
    Gold Member

    Pmb_phy, it isn't a matter of mechanical efficiency; it's purely practical. Water towers in almost all towns or cities are based upon the same principle. The regular pumping facilities can't handle peak needs, so the towers drop their load into the system when needed. During off-peak times, water is pumped up into the towers since it's not needed elsewhere. It's purely a way to smooth out the supply/demand cycle.
  17. Apr 9, 2008 #16
    Controlling the flow rate of the water is a continuous adjustment anyway, according to the needs of the Northeast Power Grid, and also according to the volume of water required to go over the Horseshoe Falls location. There's a treaty between the governments of the U.S. and Canada that requires a certain minimum amount of water to flow over the falls where the tourists are entertained, at the cost of reducing the water fed to the turbines, intentionally reducing the electrical power output.

    Sorry, I can't cite a published reference. I've visited the facilities and heard the management make speeches about how they do things. If you want to do a search, the official names of the facilities are the "Robert Moses Niagara Power Plant" and the "Lewiston Pump Generating Plant."
  18. Apr 9, 2008 #17
    Back to the Op....lol.

    Of course it does. Your two rocks now hurtling towards each other. Remember, thier total energy at the beginning is Pe+Ke. Their energy once they are in motion is STILL Pe+Ke. It's just the ratios that have changed the total remains the same.

    As an aside, to the pumping water back to the resevoir issue I have read that some hydro plants use this technique when the design specs require a certain flow to maintain good working operation of the turbines. So what do you do with the excess in a low demand time? Might as well partially refil the resevoir. Unless you are a major connection to the continental grid in our case. In which case I suspect (but stand to be corrected) the operator would rather sell the excess energy to the grid than use it to re-circ water.
  19. Apr 10, 2008 #18
    Pete, From what I understand, a photon is a particle of electromagnetic energy, which would have no mass, which would have no P.E. that is based on gravity/kinetic energy.

    Also, what do you mean by the mutual interations/interactions? I'm sure you mean the latter, from a spelling error. If so, how would this P.E. somehow turn into the mass of the
    the atom?

    Furthermore, an electron moving in the absence of a EM field would still be a quark, which has matter, and could or could not have potential kinetic energy from the potion of which it collides with other atoms, thus moving it, or causing it to vibrate.

    I'm not sure about nuclear energy. I think it comes from when the atoms split or fuse, causing tremendous amounts of vibrations, which, from what I know, is heat. Can someone clarify?

    Also, please check your spelling. It's hard to understand posts with even 1 word wrong. What does interation mean?
  20. Apr 10, 2008 #19


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Er.. an electron is its own fundamental particle, and it isn't a "quark". It is a lepton, not a hardron. It does have a mass.

    This thread has gotten very confusing. Still, do you see the fallacy with your original post, though?

  21. Apr 10, 2008 #20
    Yes, I do. Error on my part. Above is also an error.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook