Re: Suspension losses

On 1/16/2025 12:18 PM, Frank Krygowski wrote:

On 1/16/2025 7:14 AM, zen cycle wrote:

On 1/15/2025 6:39 PM, Frank Krygowski wrote:

>
You should look at the energy used for the controls and think about what becomes of it. Do that in microcopic detail.

>
If you think it all ends up as heat (IR spectrum) you have a gross misunderstanding of electronics. First off, the indicators dissipate energy in the visible light spectrum (this is why LEDs are more efficient lighting than incandescent, very little energy is used in the IR spectrum).

 OK, a thought experiment: Take an adiabatic container - that is, a _perfectly_ insulated box (a physical impossibility, but useful for our analysis). Let the box contain whatever you like - just air, some solid objects, whatever.
 Cut an LED sized hole in it and insert an LED of your choice so it shines into the box. Turn on the LED.
 What happens to the light entering the box? Obviously, you don't end up with a box full of light, so it isn't stored; it somehow goes away.

lol...no, it doesn't 'go away'. For all intents and purposes it suffers the safe fate as Schrödinger's cat.

And what happens to the temperature inside the box, and why?

It will rise somewhat due to the residual IR energy from the system. Visible spectrum LEDs do emit some IR, just not nearly as much as incandescents (given the same lux)

 Answer: The temperature of whatever's inside the box will rise. The energy put into _all_ spectra by the LED, including the visible light spectrum, ultimately converts to heat.

So _all_ forms of energy convert to heat? You should write a paper on that.

 

Secondly, think about your premise that it all turns into heat - this means no energy is available to do any other form of work.

In physics or mechanical engineering, work is defined as force moving through a distance, or torque moving though an angle of rotation. Valid units of measurement are the same as the units for energy: foot*pounds, Newton*meters or Joules, etc. all of which (interestingly) can be converted to BTUs, which are normally units measuring heat.
 And in general, you're right, energy converted to heat is not normally available to do work.

I used the term 'work' more generically, in this case running a program, setting bits in memory, etc. Yes, residual heat from the process, but energy is used to perform whatever task, Heat is the result of losses in the system (thermal junctions from die bonds, for example)

 There are exceptions, of course. A device that produces work from heat is known as an "engine."
 I bought one of these a while ago, as a geek toy. (I used to have a larger one as a demonstrator used in Thermodynamics class.)
 https://www.amazon.com/gp/product/B0BL29ZF17/ ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
 It's a small Stirling Engine driven by the temperature difference between the hot bottom plate and the colder top plate. It sits on top of a cup of hot water. Heat flows into the disk on the bottom and flows out the top one. I've gotten about 850 rpm out of mine, more if I place an ice cube on the top plate.
 So an engine is a device that converts heat to mechanical work. But no engine can covert heat to work with 100% efficiency.
 All of this discussion is stuff normally covered under the topic "Thermodynamics."
 

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