Negative Definition and 1000 Threads

So for a power supply project I need a voltage regulator giving me a positive output at around 40v. Obsessively you can not buy these, So i am useing a circuit which consists of a resistor, npn transistor, and zener diode. the positive input goes to the collector of the transistor and through...

Hi everybody, I have the following doubt. We know that for a thermodynamic system the following equality holds: $$ C_P-C_V=-T\frac{\left[\left(\frac{\partial P}{\partial T}\right)_V\right]^2}{\left(\frac{\partial P}{\partial V}\right)_T} $$ Now, the mechanical stability of the system...

Hello, I apologize if this is not posted in the right section. I've been trying to learn about negative energy, the kind that can't bend space-time, though when I try to search it, it mostly shows random sites on mythical negative spirtits being negative. So does anyone know a place I can...

I know that "negative acceleration" can be slowing down, or going backward and speeding up. I read the old posts here and I am still confused. If no velocity are given, and you only know that the acceleration is, say, a= -5 m/s^2, how do you know the object is going forward or backward?

Hello everyone, What is the square root of a square of a negative number equal to? For example: \sqrt{-1}^{2} It seems there are two possible ways of doing this, the problem is that I am getting two different answers using these two approaches i.e; We can first take the square of -1 and then...

The electrostatic energy in a capacitor is negative is it not? If one had enough positive and negative charge on the plates so that the electrostatic energy was greater in magnitude than the rest mass energy then the system as a whole would have a negative total energy. Would this be possible...

Why is it not possible to have the log of a negative number? Examples would be greatly appreciated. Furthermore, is it the base that cannot be negative? Like log-bx or is it that when you have a number and you log it, the number cannot be negative. log(-x)

Hi How are you I have a question how we can know the work if - or + also heat energy please could see this question why in answer take work as - and heat as +

Hello, I am embarking to read Spivak's book on Calculus, and have come across some difficulty with something that is perhaps rather trivial. In the third edition, there is a section entitled Basic Properties of Numbers. Near the end of page 7, the author begins discussing how he will use...

Hi I read at this link http://www.eecs.berkeley.edu/~aude/papers/TRB2012_stat_traffic.pdf something like bus travel times can be normally distributed. Sounds strange to me because normal distribution presumes even negative values Anything I am missing here? Regards

E is finite and V is infinite, So T should be negative infinite

Homework Statement \sqrt{-3y-8} = -\sqrt{y+4}+2 I need to square both sides in order to solve for Y. But, how do I distribute the negative sign on the right side? Would it be similar to (-x+2)2 or -(x+2)2?

I watched Stephan Hawking's into the universe, I know it's more of a way to make science mainstream than to educate people, but in the episode about is there a god, he said that space was a negative energy and that it equaled the same amount as the energy of the universe. I haven't looked into...

Homework Statement Ax = 3m Ay = -4m Find the angle with respect to the x axis Homework Equations Tan = Ay/Ax The Attempt at a Solution Tan = Ay/Ax = -4m/3m = 1.333333 angle = -53 degrees Is -53 degrees a correct answer or should it be positive 53?

Hi I am working on a problem that ends up having the natural log of a negative e which I'm confused on how to find the explicit solution. The Problem: Find an explicit solution with C. y'-e^{-y}cos(x)=0 My Conclusion: First of all, I'm confused how I should solve this explicitly if I'm...

I know that in logarithms we can not set as base a negative number,but look at this(in the brackets I will put the base.): log(-2)-8=3 Mathematics say that is wrong,but why? If we tell -2^3=-8 we have a correct result. So? Thank you!

Homework Statement Calculate the current through R3. Homework Equations V=IR The Attempt at a Solution my attempt is attached. My question revolves around my answer...is a negative current a legitimate answer? What does it mean?

could dark matter be negative pressure caused by the stretching of the fabric of space by an expanding universe?

Homework Statement lim [√(2x2 +1)]/(3x - 5) [SIZE="1"]x→-∞ I know that the answer is -√2/3. That is the answer my professor had on this example, and the math lab tutor also agreed, and so did my graphing calculator. But I keep getting √2/3 on paper. The math lab tutor explained yesterday why...

I asked this question because I think that acceleration could be positive (though I may be wrong.) Homework Statement The electric field near the Earth's surface has magnitude of about 150 \text{N/C} . What is the acceleration of the proton? Homework Equations Clearly, we need to use...

Homework Statement Simplify (x-2 - y-2) / (x-1 + y-1) Homework Equations The Attempt at a Solution So I just factorised the numerator into x-1 - y-1 and x-1 + y-1. And was left with x-1 - y-1 as an answer. The textbook gives (y - x) / (xy) as the answer (no working shown). So...

Does anyone know if it is possible to construct a compact 3-manifold with no boundary and negative curvature? I ask this question in the Cosmology sub-forum because I see in various writings of cosmologists that it is often taken for granted that a negatively curved Universe must be infinite...

Homework Statement Surgeons often use a type of "binocular microscope" [that's a word by word translation]. It consists of a 50mm lens close to the patient and a -15mm right in front of the doctor's eye. The distance between the patient and the 50 mm lens is 400mm and the negative lens is...

If the inequality $\sin^2 x+a\cos x+a^2 \ge 1+\cos x$ holds for any $x\in R$, determine the range of values for negative $a$.

I am watching Susskind's derivation of Newton's F=ma from the Euler-Lagrange equations (53 minutes in) here for which he uses the Lagrangian of kinetic energy minus potential energy. I have seen this done elsewhere as well. As far as I can tell, and please correct me if I'm wrong, the only...

In QFT equations, there are not only positive energy solutions, but negative ones as well. Dirac had the hole theory. But the sea may have infinite charges and gravity effects. And then QFT textbooks just explain the negative solution as anti-particle. But in the lab, we measure the...

Hello, I'm reading a book about a gas volume inside a system. It says that when the volume expands due to the heated gas, the system is doing work. I understand that part. But it says that the value for work is negative because the system is doing work. From all the physics I have been...

So I had a discussion with my brother about this (it was sort of a joke, but I am a mathematician and every joke I turn into a theorem and vice versa... :-)), it was kinda of short. But if we already have dimensions which aren't whole integer numbers (he didn't know that, and didn't seem...

This question is the very end of a large problem that I really can't figure out. It's an online course and the computer keeps saying the same thing so I am getting confused. It says simplify 1-(1-sinθ) My answer: -sinθ Computer's answer: sinθ From what I understand, it would come out...

Too familiar with Bose Hubbard model, but suddenly got stuck by a simple question: Why is the kinetic term (to be precise should be single body part) negative?

EDIT ADDED: I already got it! Thank you for your ideas! :D 1. Homework Statement If you drive an average velocity of -72.8 Km/h for 55 minutes to a position that is 28.5 KM north of Jollitown, in what position did you start your drive?I'm confused with this negative average velocity, please...

Hi guys, I understand that g is by definition positive, as in the Gravitational field strength. However, my school's notes has defined g as -(GM)/r^2. I don't understand what's that negative sign for, and in what scenario is the negative sign used? By the way, it also defined g as -(d phi/dr)...

Is it the absence and presence of an electrical fluid called as positive and negative charges?

Homework Statement A small, positively charged sphere is released from rest and moves directly away from a larger, positively charged sphere. During this process, the electrostatic force: a) does positive work and increases the kinetic energy of the small sphere b) does negative work and...

I've read recently about systems with the ability to reach negative temperature: where entropy decreases as energy increases. I have a couple question regarding this. First, how is it possible to reach negative temperature without crossing absolute zero? Is there some discontinuity like a phase...

The image bellow is the PN junction under equilibrium. I wonder why there are so many positive and negative ions in N and P types respectively. For me, I think that these ions should only exist in the depeletion region not outside the region. Thanks for help.

I'm aware that this Topic is generally considered hypothetical, but at least I'm not talking about something that someone can say, "hey, that's your personal theory". A decent number of respected physicists have published papers on one aspect of the subject, or another. There is a...

Hey guys, Are you guys aware of any designs (other than buckboost or charge pump) for negative power supplies using just a positive voltage (and ground of course) as inputs? Creative designs are totally welcome. Thanks in advance!

The Earth carries a negative electric charge of roughly 500 thousand Coulombs (according to different sources I've seen). If I touch the Earth I should therefore pick up some of this electric charge (through conduction) and become negative charged. Assuming the Earth can modeled as a conducting...

Homework Statement The kinetic energy is given by \left\langle E_{kin} \right\rangle = \frac{\left\langle \widehat{p}^2 \right\rangle}{2m} In Dirac notation we have \left\langle E_{kin} \right\rangle = \frac{1}{2m} \left\langle \widehat{p}\Psi | \widehat{p}\Psi \right\rangle Homework...

Hello, I am trying to understand induction. If I have a negatively charged rod, and two negatively charged conductors, does no induction occur? or is the induction simply the movement of the electrons from the more negatively charged conductor to the less negatively charged conductor? or does...

can negative dielectric constant be possible?if yes then for which one.

Homework Statement I'm working on a project for my circuit analysis class in which we designed a circuit that involves a wheatstone bridge, takes the voltage difference and then amplifies it to a useable level. I am past that phase of the design, I have a working circuit for that on a...

what does the positive and negative half cycles in an ac represent?

and positive when they repel? It doesn't make any sense to me at all. To what are they referring to? The way I see it, if you're got... +...- The closer they are, the less electrical potential energy they have. So it should still be positive. And if you've got two like charges C...C The...

[b]1. Homework Statement I have a sequence whereby 10000=100(1+e^(kt)+e^(2kt)+...+e^(39kt)) where k=-4.7947012×10^(-3) which was dervied from dy/dt=ky Re-arranging i get 99=1+e^(kt)+e^(2kt)+...+e^(39kt), letting e^(kt)=r I put it into the computer and i get 1.04216=r=e^-4.7947012×10^(-3)t...

Hi, this is my first time posting on these forums but I've been reading them for a while. I was having a look at metamaterials and it mentioned that metamaterials had negative permittivity and negative permeability. I also found that metals naturally had negative permittivity; though I am...

Homework Statement Note: this is actually my own question, not something from a book. So if I am wrong about some terminology please let me know In physics questions, they will tell you an electric field is |Some Value|. Since |Some Value| (lets call it X) is always positive, how do we know...

Hello, In the following voltage vs time graph as we can see the voltage becomes negative often time. My question is: if power= V*I then when voltage is negative do I have negative power?

HELP! Is my answer correct?? Is negative Friction possible?!? Homework Statement A dogsled team has four dogs that pull a person and a sled with a combined mass of 100 kg. A) They start from rest and reach a speed of 45 km/h in 2.5s. What is the average force applied by each dog? B) Suppose...