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1. Is PWM for control of Peltier Element logical?

I'm making a circuit to control the temperature of a peltier element, and I'm trying to figure out the cheapest way that will actually work over the long term, and not burn out my components fast. At first I wanted to just use standard power regulation to control the power to the element and...
2. I know this has been hammered out before, but

In my ignorant opinion, I think this just shows how flawed our knowledge of algebra is. If .999... 1, than I would hope I can answer every math question ever with 0/0 seeing as how 0/0 can be anything, but that is meaningless. So, why isn't .999... meaningless? Just because there is a rule out...
3. Studying Why maths textbooks when you can have Wikipedia?

Are you going to write a proof for that? I am joking. Wikipedia was actually blocked from my schools internet due to its inaccuracy. Not that it keeps me out. It actually really is a great source, especially ones with loads of citations, because you can go to the citation links and use those...
4. How to get one from many?

In all honesty, what I am trying to do is track back my cells. From the number of cells that I have today, back to the original gametes. I'm trying to determine how many cells I have gone through, and how long it took for me to go through them mathematically. Obviously I can add roughly 9 months...
5. How to get one from many?

First of all, since my title isn't self explanatory, what I am trying to do is take a large number and work with it such that overtime it becomes a small number. For example, I am trying to take a number like 400 and say that it came from the number one. But it came from the number 1 in such a...

Obviously energy can be made, or how would it have gotten here. Energy didn't always exist in our realm, there was a start. But on a serious note, mass is energy, but it doesn't create energy. If you try to generate elictricty by tossing a coil up a rod then when it comes back down, you just...
7. If something moved at the speed of light

That sounds cool. Where can I get that machine? :P
8. Bernoulli's law

Since the egg can't evolve, then the chicken obviously came first. If you suddenly drop the pressure in a room with a window open to the outside, then air will rush in to fill the void created by the decrease in space between atoms of air. Likewise if a sudden gust of wind enters the room...
9. Drag coefficient of a Missile

I'm going to quote N.A.S.A: "The drag coefficient is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and flow conditions on aircraft drag. The drag coefficient CD is equal to the drag D divided by the quantity: density r times half the velocity V...
10. Drag coefficient of a Missile

d and cd are different, but in determining cd, you MUST in the equation supply for the fluid dynamic drag.
11. Is there another way for nuclear reactor?

I know we use radioactive elements in nuclear reactors and the heat given of to generate electricity in the traditional steam driven turbine way, at least thats what I read. I was wondering why we can't make it more efficient through double electron capture and use captured electrons given off...
12. Drag coefficient of a Missile

Drag coefficients are based on medium: Cd = D / (.5 * r * V^2 * A) Basic Algebra, everything in an equation is inter-related. A torpedo would have a higher drag coefficient. I don't know water dynamics though. So I couldn't say how much drag water induces, other than alot. Wedges are...
13. Drag coefficient of a Missile

What kind of missile? Depending, I would say .01 - .03 depending, since missiles are relatively streamlined. A torpedo would have a higher induction of drag, so a higher drag coefficient. I'm not terribly familiar with missile design, like I am with aircraft design. this might...
14. Does this soda can anti-gravity trick have any validity?

That's what I figured, strings attached.
15. Why has nothing evolved to not need sleep?

There is no misconception on my part. You provide in post #16 that evolution occurs through mutations I presume. That is true. A random mutation could save a species, for example the rudimentary moth near a factory and darkening bark example. However, if the bark didn't darken the mutated moth...
16. Does this soda can anti-gravity trick have any validity?

I saw a trick were a guy supposedly levitated a dime with batteries, a cd, a phone, and a pepsi can. I see no reason to believe this is possible, but I'd like to find out if it is. The video is http://www.break.com/index/anti_gravity_trick.html I would appreciate some clarification on this...
17. Yet another question, Rotation and Gravity

Alright, I see. Thanks much
18. Increasing efficiency of PV cell

If you increase the amount of light going to a PVC than you will increase the amount of light it processes to a point. If you put a PVC at the focus of a Hyperbolic mirror you would maximize its light. Industrial uses of PVC's and Hyperbolic mirror are on the internet if you want to find some...
19. Yet another question, Rotation and Gravity

Okay, so if the earth stopped spinning, would it theoretically increase or decrease our aparent weight if all other factors stayed the same. Like for example if my little globe and toy analogy was taken into deep space (no forces acting on it by other bodies) would the toy spin off away from the...
20. Yet another question, Rotation and Gravity

How is centrifugal force fictitious if we can feel its effects?

Think about spinning a bucket with water around and around, what happens to the water? and in what direction is the water affected, from the center, towards the center, you are of course the center in this case
22. The Cult of the Amateur: How today's internet is killing our culture

I think misuse of the internet can kill society. But like PF for instance brings society together. I think the internet made the world smaller, and thus is not killing our culture but rather makes our culture and society blossom.
23. Pleaseee help with this question

Is the table frictionless?
24. Yet another question, Rotation and Gravity

The net force being our apparent weight on the surface of the earth?
25. Origin of the universe

Sorry Cristo. I thought that cosmology was the branch of philosophy dealing with the origin and general structure of the universe(mixed science and philosophy) , and that Astronomy was the rigid science of the universe. Honest mistake, I won't post anymore philosophy in the cosmology forums...
26. Origin of the universe

I know that what I'm about to say is more philosophical than scientific. But, the easiest way to explain the universe and where it came from etc is simply to say that the universe doesn't exist, and we don't exist at least materially. That would solve the whole problem. But why do we think etc...
27. Yet another question, Rotation and Gravity

Does that go back to e=mc^2 where if your speed increases, your mass increases. I thought that was only significant if you reached speeds closer to light. And that thus would be insignificant to the centrifugal force trying to keep people off the planet. One response to my question said the...
28. Question about going faster than speed of light

Could you elaborate. I know space time is moving and faster than the speed of light, but how does that correlate to inertial force and gravity if one is then able to move the universe?
29. Bang RIP, Bang RIP

I believe the accepted theory is that the Big Bang resulted from a sudden imbalance within the "super atom" where it all of a sudden "blew up", faster than the speed of light. The imbalance occurred when the gravity holding the atom together all of a sudden was made insignificant to the...
30. Question about going faster than speed of light

It was on the Discovery Channel. Which I would suppose is not the most accurate source of info. Seeing as how they do have a lot of misguided information on shows like Myth Busters and Dirty Jobs. However this particular show had some pretty well known astrophysicists and the like. Of course...