What topics are best for study of how gravity light works?

[stargateengineer]

I've seen a little bit about the gravity light. I think it works in a simple way, a weight at a certain height has gravitational potential energy depending on how far the weight will fall, this quantity represents the total energy we have at our disposal to power a light. Now we normally think of something falling very quickly, releasing all that potential energy in less than a second. But that is the ingenious aspect of the gravity light. The inventors figured, why not slowly release that gravitational potential energy over a period of time, at a rate which will be just enough to power a light at a reasonable brightness for a reasonable amount of time. Fascinating!

I would like to delve in a little bit into the physics that makes this possible. The mathematics involved. The thing that really pops out at me is the idea of slowly releasing the energy of a process that would normally be an explosion of energy over a very short time.

 

[davenn]

I've seen a little bit about the gravity light

what's gravity light ?

you post sounds like scifi

 

[stargateengineer]

what's gravity light ?

you post sounds like scifi

https://gravitylight.org/how-it-works/

 

[jbriggs444]

The comparison to an open wick kerosene lamp (no mantle) is more a testament to the weak light produced by a kerosene lantern than to the output of a gravity light. One tenth of a watt is not much.

 

[A.T.]

Now we normally think of something falling very quickly, releasing all that potential energy in less than a second. But that is the ingenious aspect of the gravity light. The inventors figured, why not slowly release that gravitational potential energy over a period of time

Clocks powered this way have been around for centuries. So that is not really the novel thing here, but rather combining it with modern energy efficient LEDs, in a small casing (design small but reliable gearing to provide high RPMs to the generator).

 

[jerromyjon]

at a rate which will be just enough to power a light at a reasonable brightness

I was surprised to learn that the LED limited the power flowing through the circuit to regulate the rate at which the weight falls.

 

[russ_watters]

I would like to delve in a little bit into the physics that makes this possible. The mathematics involved. The thing that really pops out at me is the idea of slowly releasing the energy of a process that would normally be an explosion of energy over a very short time.

Well, to start, calculate the gravitational potential energy of the system with the GPE equation. Then just divide the result by the time of the fall to get the power produced (or vice versa).

 

[anorlunda]

@russ_watters and @A.T. Gave you very good answers. Wind up clocks are ancient. Water clocks are ancient. What is new is LED lights that work with so little power.

 

[CWatters]

It's worth running some numbers before we all rush to cancel our electricity contract. Just how much weight do you have to lift? How high and how frequently? Here is an example...

A 40W Incandescent bulb or a 5W LED can produce about 450 Lumens. If you wanted it to operate your 5W LED for say 5 mins you would need the weight to store 1,500 Joules (5*5*60 =1500). Most houses have ceilings around 3m high so if you want your lamp to fit indoors the weight can't be lifted higher than that. To store 1500 Joules in a weight raised 3m the mass would have to be 1500/(9.81*3) = 50kg. So every 5 mins you have to put down your book and lift a 50kg weight 3m into the air.

 

[Vanadium 50]

. Most houses have ceilings around 3m high so if you want your lamp to fit indoors the weight can't be lifted higher than that.

Thomas Jefferson solved this problem by cutting a hole in his floor.

 

[A.T.]

It's worth running some numbers before we all rush to cancel our electricity contract.

Not the supposed application of this, obviously.