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Can we harness gravitational potential energy?


Why can't we harness gravity?Conservation of Momentum/Energy collision ProblemGravitational potential energyGravitational potential energy negative?How does escape velocity relate to energy and speed?Gravitational Potential Energy to Kinetic Energy ConfusionGravitational Potential Energy misunderstandingsGravitational Potential Energy ironyCan torsional force be used to harvest gravity?Gravitational Potential Energy formulasPotential gravitational energy versus potential spring energy













1












$begingroup$


I'm following this question that was closed as unclear. I think the OP meant the potential energy.



There are skyscrapers sitting there and pushing on the ground with tremendous weight. Is it possible to convert this weight/force to harness energy to power the building?



Maybe, build the building on top of some type of pendulum that will rotate under the pressure and when one cycle of rotation reaches the equilibrium point we could give it a kick from the stored energy of the same source to continue rotation.



Was something like this created or tested and found useless?



Note: maybe my question should be is it possible to convert the potential energy of a building into a kinetic?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Potential energy IS stored mechanical energy. In the case of your pendulum, that stored mechanical energy gets transferred to kinetic energy as the pendulum moves... How do you "capture" the mechanical energy being transferred into kinetic energy?
    $endgroup$
    – N. Steinle
    4 hours ago
















1












$begingroup$


I'm following this question that was closed as unclear. I think the OP meant the potential energy.



There are skyscrapers sitting there and pushing on the ground with tremendous weight. Is it possible to convert this weight/force to harness energy to power the building?



Maybe, build the building on top of some type of pendulum that will rotate under the pressure and when one cycle of rotation reaches the equilibrium point we could give it a kick from the stored energy of the same source to continue rotation.



Was something like this created or tested and found useless?



Note: maybe my question should be is it possible to convert the potential energy of a building into a kinetic?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Potential energy IS stored mechanical energy. In the case of your pendulum, that stored mechanical energy gets transferred to kinetic energy as the pendulum moves... How do you "capture" the mechanical energy being transferred into kinetic energy?
    $endgroup$
    – N. Steinle
    4 hours ago














1












1








1





$begingroup$


I'm following this question that was closed as unclear. I think the OP meant the potential energy.



There are skyscrapers sitting there and pushing on the ground with tremendous weight. Is it possible to convert this weight/force to harness energy to power the building?



Maybe, build the building on top of some type of pendulum that will rotate under the pressure and when one cycle of rotation reaches the equilibrium point we could give it a kick from the stored energy of the same source to continue rotation.



Was something like this created or tested and found useless?



Note: maybe my question should be is it possible to convert the potential energy of a building into a kinetic?










share|cite|improve this question











$endgroup$




I'm following this question that was closed as unclear. I think the OP meant the potential energy.



There are skyscrapers sitting there and pushing on the ground with tremendous weight. Is it possible to convert this weight/force to harness energy to power the building?



Maybe, build the building on top of some type of pendulum that will rotate under the pressure and when one cycle of rotation reaches the equilibrium point we could give it a kick from the stored energy of the same source to continue rotation.



Was something like this created or tested and found useless?



Note: maybe my question should be is it possible to convert the potential energy of a building into a kinetic?







energy-conservation potential-energy perpetual-motion energy-storage






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited 41 mins ago









Qmechanic

105k121901203




105k121901203










asked 4 hours ago









GrasperGrasper

1425




1425












  • $begingroup$
    Potential energy IS stored mechanical energy. In the case of your pendulum, that stored mechanical energy gets transferred to kinetic energy as the pendulum moves... How do you "capture" the mechanical energy being transferred into kinetic energy?
    $endgroup$
    – N. Steinle
    4 hours ago


















  • $begingroup$
    Potential energy IS stored mechanical energy. In the case of your pendulum, that stored mechanical energy gets transferred to kinetic energy as the pendulum moves... How do you "capture" the mechanical energy being transferred into kinetic energy?
    $endgroup$
    – N. Steinle
    4 hours ago
















$begingroup$
Potential energy IS stored mechanical energy. In the case of your pendulum, that stored mechanical energy gets transferred to kinetic energy as the pendulum moves... How do you "capture" the mechanical energy being transferred into kinetic energy?
$endgroup$
– N. Steinle
4 hours ago




$begingroup$
Potential energy IS stored mechanical energy. In the case of your pendulum, that stored mechanical energy gets transferred to kinetic energy as the pendulum moves... How do you "capture" the mechanical energy being transferred into kinetic energy?
$endgroup$
– N. Steinle
4 hours ago










5 Answers
5






active

oldest

votes


















14












$begingroup$

In classical mechanics, absolute values of potential energy are meaningless. In your case of a skyscraper just sitting there, we could say it has a large positive amount of potential energy, no potential energy, or even negative potential energy. It doesn't matter at all. What is important is a change in potential energy.




is it possible to convert the potential energy of a building into a kinetic?




Based on what is said above, you would need to decrease the potential energy of the building and find a way to harness that change in potential energy. The issue is that for gravity, the potential energy just depends on the distance from the Earth, so this would mean that you would have to move the building (or at least parts of the building) closer to the Earth. The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time, so I don't see this being feasible.



To see how gravitational potential energy can be converted to other types of energy in other systems, see some of the other posted answers.






share|cite|improve this answer











$endgroup$









  • 8




    $begingroup$
    +1 for "The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time".
    $endgroup$
    – dbmag9
    2 hours ago










  • $begingroup$
    There have been instances where a building's potential energy has been converted (briefly) into kinetic energy, but I'm not sure we care to repeat them.
    $endgroup$
    – Michael Seifert
    29 mins ago





















5












$begingroup$

An example of harnessing gravitational potential energy is a hydroelectric power plant which converts the potential energy of water falls, dams and the like into electrical energy.



As far as harnessing the potential energy of a building sitting on the ground, I suppose if you caused the building to topple you could harness the energy of the falling portions of the building. Obviously ridiculous.



All practical examples of harnessing potential energy involve its conversion to kinetic energy.Hope this helps.






share|cite|improve this answer











$endgroup$









  • 1




    $begingroup$
    If you want to describe hydroelectric power as "harnessing gravitational potential energy" then wouldn't it be more accurate to say that energy comes from the dammed lake or upriver water, rather than the dam itself or even the "waterfall" that moves the turbines?
    $endgroup$
    – talrnu
    2 hours ago










  • $begingroup$
    @talrnu The potential energy is the height of the water above the point where it drives a turbine. When it falls and reaches the turbine the potential energy has been converted to kinetic energy. Now the kinetic energy is converted to turbine work by the work energy principle.
    $endgroup$
    – Bob D
    13 mins ago










  • $begingroup$
    Or you could have a regenerative elevator: the car going down generates power to lift the car going up, so all you have to do is replace system losses.
    $endgroup$
    – jamesqf
    just now



















1












$begingroup$

Simply No. If you could generate energy simply from the potential energy of the building, induced by gravity, without somehow permanently decreasing that energy, you would build some sort of perpetuum mobile.



If you would gain usable energy (like an electrical current) out of the potential energy of the building, without reducing the mass of the building and without altering the gravitational field, you would have created energy out of nothing, but energy is conserved.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Isn't gravitational force a perpetuum mobile? or at least it has the potential to be.
    $endgroup$
    – Grasper
    4 hours ago






  • 1




    $begingroup$
    @Grasper How so? You only get energy from the gravity by moving closer together. At some point, you can't get any closer and the energy doesn't increase.
    $endgroup$
    – JMac
    4 hours ago










  • $begingroup$
    @JMac because gravity is always there available?
    $endgroup$
    – Grasper
    3 hours ago










  • $begingroup$
    @Grasper But the objects aren't always apart. You can extract some energy from the system; but in extracting that energy you remove potential energy from the system; which you can only do a finite amount until there is no potential left. In a perfect isolated system with no loss, you in theory could have it move forever without energy exchange. Wikipedia calls that "perpetual motion of the third kind", and it's still not possible in practice. en.wikipedia.org/wiki/Perpetual_motion#Classification
    $endgroup$
    – JMac
    3 hours ago










  • $begingroup$
    @JMac Since the objects are still attracted to and exert force on each other when they meet, your explanation doesn't really address the source of Grasper's confusion. The question is about why we can't generate power from these forces when the objects are touching.
    $endgroup$
    – talrnu
    3 mins ago



















0












$begingroup$

By convention, potential energy (which can be mechanical, gravitational, chemical, electromagnetic or nuclear) refers to energy stored in a field (electromagnetic field, gravitational field, gluon field etc.). This energy must be converted into kinetic energy in order to be "harnessed" or do work. For example, you can convert potential energy into:




  • kinetic energy of an arrow, a pendulum or a pipe full of water

  • heat energy (which at a molecular scale is just kinetic energy again)

  • an electric current (moving electrons, so kinetic energy again)

  • energetic neutrons and other products of fission or fusion (kinetic energy again)


So you can harness potential energy, but only indirectly.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    I understand this, maybe my question should be is it possible to convert the potential energy of a building into a kinetic?
    $endgroup$
    – Grasper
    4 hours ago






  • 1




    $begingroup$
    @Grasper Sure. A few well placed explosive charges will convert the potential energy of a building into kinetic energy for a short period, before this kinetic energy is used to break a lot of chemical bonds. I believe there are videos of the phenomena available on YouTube :) But if you want to convert some of the kinetic energy back to potential energy afterwards then you have to design a building that will bounce.
    $endgroup$
    – gandalf61
    3 hours ago












  • $begingroup$
    Speaking of bouncing, skyscrapers actually swing. There were strips created that generate electricity. They placed them under a bridge and anytime car passed it generated electricity. So if a very long string is attached this could work but in that case I think the wind energy would be more efficient but who knows.
    $endgroup$
    – Grasper
    25 mins ago



















0












$begingroup$

Yes, you can convert the potential energy of the skyscraper into useful work. But, to extract useful work from the potential energy, must reduce the potential energy, that is: you must reduce the height of the skyscraper. You must tear the skyscraper down to get its energy.



You should note that skyscrapers aren't free and that someone used a crane powered by electricity or diesel to lift the parts of the skyscraper to their current positions. You are guaranteed to get less energy out of this process than was put in to build the skyscraper. You will waste a lot of energy in the process of converting energy from diesel or the electric grid into the potential energy of the skyscraper and then back into electricity. This would be a terribly inefficient way to store energy.



However, as noted by another answer, this is essentially what we do with hydroelectric dams. We move water from a high altitude to a lower altitude and extract useful work that is converted into electrical energy. This energy is free in the sense that the sun evaporated water somewhere and it rained down on the high altitude reservoir. So hydroelectric power is, at its core, solar power, because the sun effectively pumps the water uphill and we extract energy as it moves downhill.



Using actual electrically powered pumps, you can pump water uphill to store energy. You can use the energy later by allowing it to flow downhill.






share|cite|improve this answer









$endgroup$













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    5 Answers
    5






    active

    oldest

    votes








    5 Answers
    5






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    14












    $begingroup$

    In classical mechanics, absolute values of potential energy are meaningless. In your case of a skyscraper just sitting there, we could say it has a large positive amount of potential energy, no potential energy, or even negative potential energy. It doesn't matter at all. What is important is a change in potential energy.




    is it possible to convert the potential energy of a building into a kinetic?




    Based on what is said above, you would need to decrease the potential energy of the building and find a way to harness that change in potential energy. The issue is that for gravity, the potential energy just depends on the distance from the Earth, so this would mean that you would have to move the building (or at least parts of the building) closer to the Earth. The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time, so I don't see this being feasible.



    To see how gravitational potential energy can be converted to other types of energy in other systems, see some of the other posted answers.






    share|cite|improve this answer











    $endgroup$









    • 8




      $begingroup$
      +1 for "The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time".
      $endgroup$
      – dbmag9
      2 hours ago










    • $begingroup$
      There have been instances where a building's potential energy has been converted (briefly) into kinetic energy, but I'm not sure we care to repeat them.
      $endgroup$
      – Michael Seifert
      29 mins ago


















    14












    $begingroup$

    In classical mechanics, absolute values of potential energy are meaningless. In your case of a skyscraper just sitting there, we could say it has a large positive amount of potential energy, no potential energy, or even negative potential energy. It doesn't matter at all. What is important is a change in potential energy.




    is it possible to convert the potential energy of a building into a kinetic?




    Based on what is said above, you would need to decrease the potential energy of the building and find a way to harness that change in potential energy. The issue is that for gravity, the potential energy just depends on the distance from the Earth, so this would mean that you would have to move the building (or at least parts of the building) closer to the Earth. The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time, so I don't see this being feasible.



    To see how gravitational potential energy can be converted to other types of energy in other systems, see some of the other posted answers.






    share|cite|improve this answer











    $endgroup$









    • 8




      $begingroup$
      +1 for "The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time".
      $endgroup$
      – dbmag9
      2 hours ago










    • $begingroup$
      There have been instances where a building's potential energy has been converted (briefly) into kinetic energy, but I'm not sure we care to repeat them.
      $endgroup$
      – Michael Seifert
      29 mins ago
















    14












    14








    14





    $begingroup$

    In classical mechanics, absolute values of potential energy are meaningless. In your case of a skyscraper just sitting there, we could say it has a large positive amount of potential energy, no potential energy, or even negative potential energy. It doesn't matter at all. What is important is a change in potential energy.




    is it possible to convert the potential energy of a building into a kinetic?




    Based on what is said above, you would need to decrease the potential energy of the building and find a way to harness that change in potential energy. The issue is that for gravity, the potential energy just depends on the distance from the Earth, so this would mean that you would have to move the building (or at least parts of the building) closer to the Earth. The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time, so I don't see this being feasible.



    To see how gravitational potential energy can be converted to other types of energy in other systems, see some of the other posted answers.






    share|cite|improve this answer











    $endgroup$



    In classical mechanics, absolute values of potential energy are meaningless. In your case of a skyscraper just sitting there, we could say it has a large positive amount of potential energy, no potential energy, or even negative potential energy. It doesn't matter at all. What is important is a change in potential energy.




    is it possible to convert the potential energy of a building into a kinetic?




    Based on what is said above, you would need to decrease the potential energy of the building and find a way to harness that change in potential energy. The issue is that for gravity, the potential energy just depends on the distance from the Earth, so this would mean that you would have to move the building (or at least parts of the building) closer to the Earth. The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time, so I don't see this being feasible.



    To see how gravitational potential energy can be converted to other types of energy in other systems, see some of the other posted answers.







    share|cite|improve this answer














    share|cite|improve this answer



    share|cite|improve this answer








    edited 2 hours ago

























    answered 3 hours ago









    Aaron StevensAaron Stevens

    11.5k31946




    11.5k31946








    • 8




      $begingroup$
      +1 for "The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time".
      $endgroup$
      – dbmag9
      2 hours ago










    • $begingroup$
      There have been instances where a building's potential energy has been converted (briefly) into kinetic energy, but I'm not sure we care to repeat them.
      $endgroup$
      – Michael Seifert
      29 mins ago
















    • 8




      $begingroup$
      +1 for "The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time".
      $endgroup$
      – dbmag9
      2 hours ago










    • $begingroup$
      There have been instances where a building's potential energy has been converted (briefly) into kinetic energy, but I'm not sure we care to repeat them.
      $endgroup$
      – Michael Seifert
      29 mins ago










    8




    8




    $begingroup$
    +1 for "The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time".
    $endgroup$
    – dbmag9
    2 hours ago




    $begingroup$
    +1 for "The utility of buildings is typically that they remain stationary so people can use them consistently and for a long time".
    $endgroup$
    – dbmag9
    2 hours ago












    $begingroup$
    There have been instances where a building's potential energy has been converted (briefly) into kinetic energy, but I'm not sure we care to repeat them.
    $endgroup$
    – Michael Seifert
    29 mins ago






    $begingroup$
    There have been instances where a building's potential energy has been converted (briefly) into kinetic energy, but I'm not sure we care to repeat them.
    $endgroup$
    – Michael Seifert
    29 mins ago













    5












    $begingroup$

    An example of harnessing gravitational potential energy is a hydroelectric power plant which converts the potential energy of water falls, dams and the like into electrical energy.



    As far as harnessing the potential energy of a building sitting on the ground, I suppose if you caused the building to topple you could harness the energy of the falling portions of the building. Obviously ridiculous.



    All practical examples of harnessing potential energy involve its conversion to kinetic energy.Hope this helps.






    share|cite|improve this answer











    $endgroup$









    • 1




      $begingroup$
      If you want to describe hydroelectric power as "harnessing gravitational potential energy" then wouldn't it be more accurate to say that energy comes from the dammed lake or upriver water, rather than the dam itself or even the "waterfall" that moves the turbines?
      $endgroup$
      – talrnu
      2 hours ago










    • $begingroup$
      @talrnu The potential energy is the height of the water above the point where it drives a turbine. When it falls and reaches the turbine the potential energy has been converted to kinetic energy. Now the kinetic energy is converted to turbine work by the work energy principle.
      $endgroup$
      – Bob D
      13 mins ago










    • $begingroup$
      Or you could have a regenerative elevator: the car going down generates power to lift the car going up, so all you have to do is replace system losses.
      $endgroup$
      – jamesqf
      just now
















    5












    $begingroup$

    An example of harnessing gravitational potential energy is a hydroelectric power plant which converts the potential energy of water falls, dams and the like into electrical energy.



    As far as harnessing the potential energy of a building sitting on the ground, I suppose if you caused the building to topple you could harness the energy of the falling portions of the building. Obviously ridiculous.



    All practical examples of harnessing potential energy involve its conversion to kinetic energy.Hope this helps.






    share|cite|improve this answer











    $endgroup$









    • 1




      $begingroup$
      If you want to describe hydroelectric power as "harnessing gravitational potential energy" then wouldn't it be more accurate to say that energy comes from the dammed lake or upriver water, rather than the dam itself or even the "waterfall" that moves the turbines?
      $endgroup$
      – talrnu
      2 hours ago










    • $begingroup$
      @talrnu The potential energy is the height of the water above the point where it drives a turbine. When it falls and reaches the turbine the potential energy has been converted to kinetic energy. Now the kinetic energy is converted to turbine work by the work energy principle.
      $endgroup$
      – Bob D
      13 mins ago










    • $begingroup$
      Or you could have a regenerative elevator: the car going down generates power to lift the car going up, so all you have to do is replace system losses.
      $endgroup$
      – jamesqf
      just now














    5












    5








    5





    $begingroup$

    An example of harnessing gravitational potential energy is a hydroelectric power plant which converts the potential energy of water falls, dams and the like into electrical energy.



    As far as harnessing the potential energy of a building sitting on the ground, I suppose if you caused the building to topple you could harness the energy of the falling portions of the building. Obviously ridiculous.



    All practical examples of harnessing potential energy involve its conversion to kinetic energy.Hope this helps.






    share|cite|improve this answer











    $endgroup$



    An example of harnessing gravitational potential energy is a hydroelectric power plant which converts the potential energy of water falls, dams and the like into electrical energy.



    As far as harnessing the potential energy of a building sitting on the ground, I suppose if you caused the building to topple you could harness the energy of the falling portions of the building. Obviously ridiculous.



    All practical examples of harnessing potential energy involve its conversion to kinetic energy.Hope this helps.







    share|cite|improve this answer














    share|cite|improve this answer



    share|cite|improve this answer








    edited 3 hours ago

























    answered 4 hours ago









    Bob DBob D

    3,2282215




    3,2282215








    • 1




      $begingroup$
      If you want to describe hydroelectric power as "harnessing gravitational potential energy" then wouldn't it be more accurate to say that energy comes from the dammed lake or upriver water, rather than the dam itself or even the "waterfall" that moves the turbines?
      $endgroup$
      – talrnu
      2 hours ago










    • $begingroup$
      @talrnu The potential energy is the height of the water above the point where it drives a turbine. When it falls and reaches the turbine the potential energy has been converted to kinetic energy. Now the kinetic energy is converted to turbine work by the work energy principle.
      $endgroup$
      – Bob D
      13 mins ago










    • $begingroup$
      Or you could have a regenerative elevator: the car going down generates power to lift the car going up, so all you have to do is replace system losses.
      $endgroup$
      – jamesqf
      just now














    • 1




      $begingroup$
      If you want to describe hydroelectric power as "harnessing gravitational potential energy" then wouldn't it be more accurate to say that energy comes from the dammed lake or upriver water, rather than the dam itself or even the "waterfall" that moves the turbines?
      $endgroup$
      – talrnu
      2 hours ago










    • $begingroup$
      @talrnu The potential energy is the height of the water above the point where it drives a turbine. When it falls and reaches the turbine the potential energy has been converted to kinetic energy. Now the kinetic energy is converted to turbine work by the work energy principle.
      $endgroup$
      – Bob D
      13 mins ago










    • $begingroup$
      Or you could have a regenerative elevator: the car going down generates power to lift the car going up, so all you have to do is replace system losses.
      $endgroup$
      – jamesqf
      just now








    1




    1




    $begingroup$
    If you want to describe hydroelectric power as "harnessing gravitational potential energy" then wouldn't it be more accurate to say that energy comes from the dammed lake or upriver water, rather than the dam itself or even the "waterfall" that moves the turbines?
    $endgroup$
    – talrnu
    2 hours ago




    $begingroup$
    If you want to describe hydroelectric power as "harnessing gravitational potential energy" then wouldn't it be more accurate to say that energy comes from the dammed lake or upriver water, rather than the dam itself or even the "waterfall" that moves the turbines?
    $endgroup$
    – talrnu
    2 hours ago












    $begingroup$
    @talrnu The potential energy is the height of the water above the point where it drives a turbine. When it falls and reaches the turbine the potential energy has been converted to kinetic energy. Now the kinetic energy is converted to turbine work by the work energy principle.
    $endgroup$
    – Bob D
    13 mins ago




    $begingroup$
    @talrnu The potential energy is the height of the water above the point where it drives a turbine. When it falls and reaches the turbine the potential energy has been converted to kinetic energy. Now the kinetic energy is converted to turbine work by the work energy principle.
    $endgroup$
    – Bob D
    13 mins ago












    $begingroup$
    Or you could have a regenerative elevator: the car going down generates power to lift the car going up, so all you have to do is replace system losses.
    $endgroup$
    – jamesqf
    just now




    $begingroup$
    Or you could have a regenerative elevator: the car going down generates power to lift the car going up, so all you have to do is replace system losses.
    $endgroup$
    – jamesqf
    just now











    1












    $begingroup$

    Simply No. If you could generate energy simply from the potential energy of the building, induced by gravity, without somehow permanently decreasing that energy, you would build some sort of perpetuum mobile.



    If you would gain usable energy (like an electrical current) out of the potential energy of the building, without reducing the mass of the building and without altering the gravitational field, you would have created energy out of nothing, but energy is conserved.






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      Isn't gravitational force a perpetuum mobile? or at least it has the potential to be.
      $endgroup$
      – Grasper
      4 hours ago






    • 1




      $begingroup$
      @Grasper How so? You only get energy from the gravity by moving closer together. At some point, you can't get any closer and the energy doesn't increase.
      $endgroup$
      – JMac
      4 hours ago










    • $begingroup$
      @JMac because gravity is always there available?
      $endgroup$
      – Grasper
      3 hours ago










    • $begingroup$
      @Grasper But the objects aren't always apart. You can extract some energy from the system; but in extracting that energy you remove potential energy from the system; which you can only do a finite amount until there is no potential left. In a perfect isolated system with no loss, you in theory could have it move forever without energy exchange. Wikipedia calls that "perpetual motion of the third kind", and it's still not possible in practice. en.wikipedia.org/wiki/Perpetual_motion#Classification
      $endgroup$
      – JMac
      3 hours ago










    • $begingroup$
      @JMac Since the objects are still attracted to and exert force on each other when they meet, your explanation doesn't really address the source of Grasper's confusion. The question is about why we can't generate power from these forces when the objects are touching.
      $endgroup$
      – talrnu
      3 mins ago
















    1












    $begingroup$

    Simply No. If you could generate energy simply from the potential energy of the building, induced by gravity, without somehow permanently decreasing that energy, you would build some sort of perpetuum mobile.



    If you would gain usable energy (like an electrical current) out of the potential energy of the building, without reducing the mass of the building and without altering the gravitational field, you would have created energy out of nothing, but energy is conserved.






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      Isn't gravitational force a perpetuum mobile? or at least it has the potential to be.
      $endgroup$
      – Grasper
      4 hours ago






    • 1




      $begingroup$
      @Grasper How so? You only get energy from the gravity by moving closer together. At some point, you can't get any closer and the energy doesn't increase.
      $endgroup$
      – JMac
      4 hours ago










    • $begingroup$
      @JMac because gravity is always there available?
      $endgroup$
      – Grasper
      3 hours ago










    • $begingroup$
      @Grasper But the objects aren't always apart. You can extract some energy from the system; but in extracting that energy you remove potential energy from the system; which you can only do a finite amount until there is no potential left. In a perfect isolated system with no loss, you in theory could have it move forever without energy exchange. Wikipedia calls that "perpetual motion of the third kind", and it's still not possible in practice. en.wikipedia.org/wiki/Perpetual_motion#Classification
      $endgroup$
      – JMac
      3 hours ago










    • $begingroup$
      @JMac Since the objects are still attracted to and exert force on each other when they meet, your explanation doesn't really address the source of Grasper's confusion. The question is about why we can't generate power from these forces when the objects are touching.
      $endgroup$
      – talrnu
      3 mins ago














    1












    1








    1





    $begingroup$

    Simply No. If you could generate energy simply from the potential energy of the building, induced by gravity, without somehow permanently decreasing that energy, you would build some sort of perpetuum mobile.



    If you would gain usable energy (like an electrical current) out of the potential energy of the building, without reducing the mass of the building and without altering the gravitational field, you would have created energy out of nothing, but energy is conserved.






    share|cite|improve this answer









    $endgroup$



    Simply No. If you could generate energy simply from the potential energy of the building, induced by gravity, without somehow permanently decreasing that energy, you would build some sort of perpetuum mobile.



    If you would gain usable energy (like an electrical current) out of the potential energy of the building, without reducing the mass of the building and without altering the gravitational field, you would have created energy out of nothing, but energy is conserved.







    share|cite|improve this answer












    share|cite|improve this answer



    share|cite|improve this answer










    answered 4 hours ago









    Patrik PuchertPatrik Puchert

    112




    112












    • $begingroup$
      Isn't gravitational force a perpetuum mobile? or at least it has the potential to be.
      $endgroup$
      – Grasper
      4 hours ago






    • 1




      $begingroup$
      @Grasper How so? You only get energy from the gravity by moving closer together. At some point, you can't get any closer and the energy doesn't increase.
      $endgroup$
      – JMac
      4 hours ago










    • $begingroup$
      @JMac because gravity is always there available?
      $endgroup$
      – Grasper
      3 hours ago










    • $begingroup$
      @Grasper But the objects aren't always apart. You can extract some energy from the system; but in extracting that energy you remove potential energy from the system; which you can only do a finite amount until there is no potential left. In a perfect isolated system with no loss, you in theory could have it move forever without energy exchange. Wikipedia calls that "perpetual motion of the third kind", and it's still not possible in practice. en.wikipedia.org/wiki/Perpetual_motion#Classification
      $endgroup$
      – JMac
      3 hours ago










    • $begingroup$
      @JMac Since the objects are still attracted to and exert force on each other when they meet, your explanation doesn't really address the source of Grasper's confusion. The question is about why we can't generate power from these forces when the objects are touching.
      $endgroup$
      – talrnu
      3 mins ago


















    • $begingroup$
      Isn't gravitational force a perpetuum mobile? or at least it has the potential to be.
      $endgroup$
      – Grasper
      4 hours ago






    • 1




      $begingroup$
      @Grasper How so? You only get energy from the gravity by moving closer together. At some point, you can't get any closer and the energy doesn't increase.
      $endgroup$
      – JMac
      4 hours ago










    • $begingroup$
      @JMac because gravity is always there available?
      $endgroup$
      – Grasper
      3 hours ago










    • $begingroup$
      @Grasper But the objects aren't always apart. You can extract some energy from the system; but in extracting that energy you remove potential energy from the system; which you can only do a finite amount until there is no potential left. In a perfect isolated system with no loss, you in theory could have it move forever without energy exchange. Wikipedia calls that "perpetual motion of the third kind", and it's still not possible in practice. en.wikipedia.org/wiki/Perpetual_motion#Classification
      $endgroup$
      – JMac
      3 hours ago










    • $begingroup$
      @JMac Since the objects are still attracted to and exert force on each other when they meet, your explanation doesn't really address the source of Grasper's confusion. The question is about why we can't generate power from these forces when the objects are touching.
      $endgroup$
      – talrnu
      3 mins ago
















    $begingroup$
    Isn't gravitational force a perpetuum mobile? or at least it has the potential to be.
    $endgroup$
    – Grasper
    4 hours ago




    $begingroup$
    Isn't gravitational force a perpetuum mobile? or at least it has the potential to be.
    $endgroup$
    – Grasper
    4 hours ago




    1




    1




    $begingroup$
    @Grasper How so? You only get energy from the gravity by moving closer together. At some point, you can't get any closer and the energy doesn't increase.
    $endgroup$
    – JMac
    4 hours ago




    $begingroup$
    @Grasper How so? You only get energy from the gravity by moving closer together. At some point, you can't get any closer and the energy doesn't increase.
    $endgroup$
    – JMac
    4 hours ago












    $begingroup$
    @JMac because gravity is always there available?
    $endgroup$
    – Grasper
    3 hours ago




    $begingroup$
    @JMac because gravity is always there available?
    $endgroup$
    – Grasper
    3 hours ago












    $begingroup$
    @Grasper But the objects aren't always apart. You can extract some energy from the system; but in extracting that energy you remove potential energy from the system; which you can only do a finite amount until there is no potential left. In a perfect isolated system with no loss, you in theory could have it move forever without energy exchange. Wikipedia calls that "perpetual motion of the third kind", and it's still not possible in practice. en.wikipedia.org/wiki/Perpetual_motion#Classification
    $endgroup$
    – JMac
    3 hours ago




    $begingroup$
    @Grasper But the objects aren't always apart. You can extract some energy from the system; but in extracting that energy you remove potential energy from the system; which you can only do a finite amount until there is no potential left. In a perfect isolated system with no loss, you in theory could have it move forever without energy exchange. Wikipedia calls that "perpetual motion of the third kind", and it's still not possible in practice. en.wikipedia.org/wiki/Perpetual_motion#Classification
    $endgroup$
    – JMac
    3 hours ago












    $begingroup$
    @JMac Since the objects are still attracted to and exert force on each other when they meet, your explanation doesn't really address the source of Grasper's confusion. The question is about why we can't generate power from these forces when the objects are touching.
    $endgroup$
    – talrnu
    3 mins ago




    $begingroup$
    @JMac Since the objects are still attracted to and exert force on each other when they meet, your explanation doesn't really address the source of Grasper's confusion. The question is about why we can't generate power from these forces when the objects are touching.
    $endgroup$
    – talrnu
    3 mins ago











    0












    $begingroup$

    By convention, potential energy (which can be mechanical, gravitational, chemical, electromagnetic or nuclear) refers to energy stored in a field (electromagnetic field, gravitational field, gluon field etc.). This energy must be converted into kinetic energy in order to be "harnessed" or do work. For example, you can convert potential energy into:




    • kinetic energy of an arrow, a pendulum or a pipe full of water

    • heat energy (which at a molecular scale is just kinetic energy again)

    • an electric current (moving electrons, so kinetic energy again)

    • energetic neutrons and other products of fission or fusion (kinetic energy again)


    So you can harness potential energy, but only indirectly.






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      I understand this, maybe my question should be is it possible to convert the potential energy of a building into a kinetic?
      $endgroup$
      – Grasper
      4 hours ago






    • 1




      $begingroup$
      @Grasper Sure. A few well placed explosive charges will convert the potential energy of a building into kinetic energy for a short period, before this kinetic energy is used to break a lot of chemical bonds. I believe there are videos of the phenomena available on YouTube :) But if you want to convert some of the kinetic energy back to potential energy afterwards then you have to design a building that will bounce.
      $endgroup$
      – gandalf61
      3 hours ago












    • $begingroup$
      Speaking of bouncing, skyscrapers actually swing. There were strips created that generate electricity. They placed them under a bridge and anytime car passed it generated electricity. So if a very long string is attached this could work but in that case I think the wind energy would be more efficient but who knows.
      $endgroup$
      – Grasper
      25 mins ago
















    0












    $begingroup$

    By convention, potential energy (which can be mechanical, gravitational, chemical, electromagnetic or nuclear) refers to energy stored in a field (electromagnetic field, gravitational field, gluon field etc.). This energy must be converted into kinetic energy in order to be "harnessed" or do work. For example, you can convert potential energy into:




    • kinetic energy of an arrow, a pendulum or a pipe full of water

    • heat energy (which at a molecular scale is just kinetic energy again)

    • an electric current (moving electrons, so kinetic energy again)

    • energetic neutrons and other products of fission or fusion (kinetic energy again)


    So you can harness potential energy, but only indirectly.






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      I understand this, maybe my question should be is it possible to convert the potential energy of a building into a kinetic?
      $endgroup$
      – Grasper
      4 hours ago






    • 1




      $begingroup$
      @Grasper Sure. A few well placed explosive charges will convert the potential energy of a building into kinetic energy for a short period, before this kinetic energy is used to break a lot of chemical bonds. I believe there are videos of the phenomena available on YouTube :) But if you want to convert some of the kinetic energy back to potential energy afterwards then you have to design a building that will bounce.
      $endgroup$
      – gandalf61
      3 hours ago












    • $begingroup$
      Speaking of bouncing, skyscrapers actually swing. There were strips created that generate electricity. They placed them under a bridge and anytime car passed it generated electricity. So if a very long string is attached this could work but in that case I think the wind energy would be more efficient but who knows.
      $endgroup$
      – Grasper
      25 mins ago














    0












    0








    0





    $begingroup$

    By convention, potential energy (which can be mechanical, gravitational, chemical, electromagnetic or nuclear) refers to energy stored in a field (electromagnetic field, gravitational field, gluon field etc.). This energy must be converted into kinetic energy in order to be "harnessed" or do work. For example, you can convert potential energy into:




    • kinetic energy of an arrow, a pendulum or a pipe full of water

    • heat energy (which at a molecular scale is just kinetic energy again)

    • an electric current (moving electrons, so kinetic energy again)

    • energetic neutrons and other products of fission or fusion (kinetic energy again)


    So you can harness potential energy, but only indirectly.






    share|cite|improve this answer









    $endgroup$



    By convention, potential energy (which can be mechanical, gravitational, chemical, electromagnetic or nuclear) refers to energy stored in a field (electromagnetic field, gravitational field, gluon field etc.). This energy must be converted into kinetic energy in order to be "harnessed" or do work. For example, you can convert potential energy into:




    • kinetic energy of an arrow, a pendulum or a pipe full of water

    • heat energy (which at a molecular scale is just kinetic energy again)

    • an electric current (moving electrons, so kinetic energy again)

    • energetic neutrons and other products of fission or fusion (kinetic energy again)


    So you can harness potential energy, but only indirectly.







    share|cite|improve this answer












    share|cite|improve this answer



    share|cite|improve this answer










    answered 4 hours ago









    gandalf61gandalf61

    29915




    29915












    • $begingroup$
      I understand this, maybe my question should be is it possible to convert the potential energy of a building into a kinetic?
      $endgroup$
      – Grasper
      4 hours ago






    • 1




      $begingroup$
      @Grasper Sure. A few well placed explosive charges will convert the potential energy of a building into kinetic energy for a short period, before this kinetic energy is used to break a lot of chemical bonds. I believe there are videos of the phenomena available on YouTube :) But if you want to convert some of the kinetic energy back to potential energy afterwards then you have to design a building that will bounce.
      $endgroup$
      – gandalf61
      3 hours ago












    • $begingroup$
      Speaking of bouncing, skyscrapers actually swing. There were strips created that generate electricity. They placed them under a bridge and anytime car passed it generated electricity. So if a very long string is attached this could work but in that case I think the wind energy would be more efficient but who knows.
      $endgroup$
      – Grasper
      25 mins ago


















    • $begingroup$
      I understand this, maybe my question should be is it possible to convert the potential energy of a building into a kinetic?
      $endgroup$
      – Grasper
      4 hours ago






    • 1




      $begingroup$
      @Grasper Sure. A few well placed explosive charges will convert the potential energy of a building into kinetic energy for a short period, before this kinetic energy is used to break a lot of chemical bonds. I believe there are videos of the phenomena available on YouTube :) But if you want to convert some of the kinetic energy back to potential energy afterwards then you have to design a building that will bounce.
      $endgroup$
      – gandalf61
      3 hours ago












    • $begingroup$
      Speaking of bouncing, skyscrapers actually swing. There were strips created that generate electricity. They placed them under a bridge and anytime car passed it generated electricity. So if a very long string is attached this could work but in that case I think the wind energy would be more efficient but who knows.
      $endgroup$
      – Grasper
      25 mins ago
















    $begingroup$
    I understand this, maybe my question should be is it possible to convert the potential energy of a building into a kinetic?
    $endgroup$
    – Grasper
    4 hours ago




    $begingroup$
    I understand this, maybe my question should be is it possible to convert the potential energy of a building into a kinetic?
    $endgroup$
    – Grasper
    4 hours ago




    1




    1




    $begingroup$
    @Grasper Sure. A few well placed explosive charges will convert the potential energy of a building into kinetic energy for a short period, before this kinetic energy is used to break a lot of chemical bonds. I believe there are videos of the phenomena available on YouTube :) But if you want to convert some of the kinetic energy back to potential energy afterwards then you have to design a building that will bounce.
    $endgroup$
    – gandalf61
    3 hours ago






    $begingroup$
    @Grasper Sure. A few well placed explosive charges will convert the potential energy of a building into kinetic energy for a short period, before this kinetic energy is used to break a lot of chemical bonds. I believe there are videos of the phenomena available on YouTube :) But if you want to convert some of the kinetic energy back to potential energy afterwards then you have to design a building that will bounce.
    $endgroup$
    – gandalf61
    3 hours ago














    $begingroup$
    Speaking of bouncing, skyscrapers actually swing. There were strips created that generate electricity. They placed them under a bridge and anytime car passed it generated electricity. So if a very long string is attached this could work but in that case I think the wind energy would be more efficient but who knows.
    $endgroup$
    – Grasper
    25 mins ago




    $begingroup$
    Speaking of bouncing, skyscrapers actually swing. There were strips created that generate electricity. They placed them under a bridge and anytime car passed it generated electricity. So if a very long string is attached this could work but in that case I think the wind energy would be more efficient but who knows.
    $endgroup$
    – Grasper
    25 mins ago











    0












    $begingroup$

    Yes, you can convert the potential energy of the skyscraper into useful work. But, to extract useful work from the potential energy, must reduce the potential energy, that is: you must reduce the height of the skyscraper. You must tear the skyscraper down to get its energy.



    You should note that skyscrapers aren't free and that someone used a crane powered by electricity or diesel to lift the parts of the skyscraper to their current positions. You are guaranteed to get less energy out of this process than was put in to build the skyscraper. You will waste a lot of energy in the process of converting energy from diesel or the electric grid into the potential energy of the skyscraper and then back into electricity. This would be a terribly inefficient way to store energy.



    However, as noted by another answer, this is essentially what we do with hydroelectric dams. We move water from a high altitude to a lower altitude and extract useful work that is converted into electrical energy. This energy is free in the sense that the sun evaporated water somewhere and it rained down on the high altitude reservoir. So hydroelectric power is, at its core, solar power, because the sun effectively pumps the water uphill and we extract energy as it moves downhill.



    Using actual electrically powered pumps, you can pump water uphill to store energy. You can use the energy later by allowing it to flow downhill.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      Yes, you can convert the potential energy of the skyscraper into useful work. But, to extract useful work from the potential energy, must reduce the potential energy, that is: you must reduce the height of the skyscraper. You must tear the skyscraper down to get its energy.



      You should note that skyscrapers aren't free and that someone used a crane powered by electricity or diesel to lift the parts of the skyscraper to their current positions. You are guaranteed to get less energy out of this process than was put in to build the skyscraper. You will waste a lot of energy in the process of converting energy from diesel or the electric grid into the potential energy of the skyscraper and then back into electricity. This would be a terribly inefficient way to store energy.



      However, as noted by another answer, this is essentially what we do with hydroelectric dams. We move water from a high altitude to a lower altitude and extract useful work that is converted into electrical energy. This energy is free in the sense that the sun evaporated water somewhere and it rained down on the high altitude reservoir. So hydroelectric power is, at its core, solar power, because the sun effectively pumps the water uphill and we extract energy as it moves downhill.



      Using actual electrically powered pumps, you can pump water uphill to store energy. You can use the energy later by allowing it to flow downhill.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        Yes, you can convert the potential energy of the skyscraper into useful work. But, to extract useful work from the potential energy, must reduce the potential energy, that is: you must reduce the height of the skyscraper. You must tear the skyscraper down to get its energy.



        You should note that skyscrapers aren't free and that someone used a crane powered by electricity or diesel to lift the parts of the skyscraper to their current positions. You are guaranteed to get less energy out of this process than was put in to build the skyscraper. You will waste a lot of energy in the process of converting energy from diesel or the electric grid into the potential energy of the skyscraper and then back into electricity. This would be a terribly inefficient way to store energy.



        However, as noted by another answer, this is essentially what we do with hydroelectric dams. We move water from a high altitude to a lower altitude and extract useful work that is converted into electrical energy. This energy is free in the sense that the sun evaporated water somewhere and it rained down on the high altitude reservoir. So hydroelectric power is, at its core, solar power, because the sun effectively pumps the water uphill and we extract energy as it moves downhill.



        Using actual electrically powered pumps, you can pump water uphill to store energy. You can use the energy later by allowing it to flow downhill.






        share|cite|improve this answer









        $endgroup$



        Yes, you can convert the potential energy of the skyscraper into useful work. But, to extract useful work from the potential energy, must reduce the potential energy, that is: you must reduce the height of the skyscraper. You must tear the skyscraper down to get its energy.



        You should note that skyscrapers aren't free and that someone used a crane powered by electricity or diesel to lift the parts of the skyscraper to their current positions. You are guaranteed to get less energy out of this process than was put in to build the skyscraper. You will waste a lot of energy in the process of converting energy from diesel or the electric grid into the potential energy of the skyscraper and then back into electricity. This would be a terribly inefficient way to store energy.



        However, as noted by another answer, this is essentially what we do with hydroelectric dams. We move water from a high altitude to a lower altitude and extract useful work that is converted into electrical energy. This energy is free in the sense that the sun evaporated water somewhere and it rained down on the high altitude reservoir. So hydroelectric power is, at its core, solar power, because the sun effectively pumps the water uphill and we extract energy as it moves downhill.



        Using actual electrically powered pumps, you can pump water uphill to store energy. You can use the energy later by allowing it to flow downhill.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered 43 mins ago









        WaterMoleculeWaterMolecule

        21114




        21114






























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