Recent content by jschmidt

I don't think any engine in the world is based directly upon Carnot - isn't Carnot just an idealization of what the best possible thermal cycle is? But, it's my understanding that, at least for some engine types, the Carnot Theorem applies (for example, I've heard people talking about electric...

Thanks for all the input everyone. I found this to be quite an interesting discussion. I'm glad I asked! I kind of suspected that other factors might "overcome" any possible Carnot efficiency gains in the winter. I know some folks talked about how the engines are essentially designed to run...

Well, I had forgotten about that (it's something that's not often discussed), but I believe pretty much the entire U.S. has this winter/summer gas difference. I think it's required by the EPA. Might be similar in UK/Western Europe, not sure. My impression is that Eastern Europe, Russia, and Asia...

In addition to the excellent points made by some of the previous posters, you also seem to not be taking into account that the outflow pipe is at a lower elevation than the turbine. In other words, gravity continues to pull on the water after it has gone through the turbine, slowed down, but...

I was thinking about the Carnot Theorem, and thinking how that applies to a car's engine. T_hot would be the temperature of combustion for the fuel/air mixture, which, once the car's engine has been operating for a few minutes under load, should reach a stable maximum. I think that T_cold would...

Why can't the boat be accellerating? I never said it was moving at a constant speed. It's my understanding - is this wrong - that in general, even if accelleration is happening, the work is still just the Force (or net Force, depending on what you're trying to calculate) times the distance...

Hi, It's been a few years since my physics classes, and I want to do a quick double check to make sure I correctly remember the fundamentals of mechanical work. 1) At the most basic level, work is a force applied to an object, across a distance (that is, work cannot be calculated where...

I'm not sure if this is the best topical forum to put this question or not, but it seemed the most likely of the forums on pf.com. Anyhow, sorry if this is not in the right place. I've been hearing over the last year or two that climate scientists are very worried about very large releases of...

I don't believe this forum exists for *doing other people's homework for them*. If your friend is working on the problem, and is running into an error, and wants to post his work thus far, I bet people would be willing to help him find where he's going wrong. If he needs help getting started, if...

Could you try rephrasing that? I'm not trying to be mean, I just really have no idea what you're asking? (I'd just like to say that I have respect for anyone trying to discuss science in a foreign language, because of all the domain-specific technical vocabulary, and because of the...

Well, I think from his previous posts, he's envisioning an over-land pipeline coming from a nearby body of water to the drilling site, but in traversing across the land, it has to go up an elevation of like 9 meters before reaching the bore hole. It does seem to me like the pipe would act as...

I think because, while randomness is one aspect of entropy (I think?) it's not the only aspect. I think 'density' of energy is also an aspect of it. As energy becomes more diffuse, I think, entropy is said to increase? I have to admit that I find, currently, Entropy to be one of the more...

I would like to try to add some signal to the noise in this thread due to, I think, some mis-communication. One of the neat things about a siphon is that, although it's true that the ultimate output MUST BE LOWER than the source (that's the part about gravity which some of the posters were...

I got to thinking about this recently, when thinking about various proposed "renewable energy" systems based on tidal energy capture. Tidal energy is, basically, caused by the interaction of the kinetic energy of rotation of the earth/oceans, the kinetic energy of the moon's orbit, and the...

Well, I look at angular momentum like this: there is linear velocity, and a corresponding linear momentum. We have the concept of angular velocity (how many rotations, degrees, or rads per unit time that something is rotating/orbiting). Angular velocity is useful because it abstracts out the...