Negative Definition and 1000 Threads

I'm trying to validate some experimental data on a NACA 643-418 wing section from XFoil. Below are some basis data, Number of panels around the airfoil - 43 Mach number - 0.0487 Reynold number - 1107872 Velocity - 16.67 (not important) During the analysis I have set the upper surface...

Hi Say I have a real quantity given by x(t) = \int_{ - \infty }^\infty {\tilde x(\omega )e^{ - i\omega t} d\omega } Now I complex conjugate it (remember it is real) x(t) = \int_{ - \infty }^\infty {\tilde x^* (\omega )e^{ + i\omega t} d\omega } How is it that I from...

how to determine which is the answer to positive sqrt and negative sqrt in this problem? substituting works but what if the equation is very long and you can't use calcu or computers http://i.imgur.com/SkcQZ.png also is there a way to solve this without squaring both sides?

What i mean to say is, for example we have two plates, one positive the other negative... By convention the positive is said to be at a higher potential than the negative one.. But what if i put an electron between these two plates. The electron would obviously go towards the positive...

Negative electrical charge on water?? Help! Hello everyone: I have heard about paint sprayers that put a charge on the paint as it exits the sprayer - the charged paint is then attracted to the metal surface being painted, provided the metal surface is charged with the opposite charge. My...

can anyone help me to get this quotation "e^(-x)" on ti-89 ? after i putting "-" before "x" and pressing enter , the error syntax happens ... :confused:

Homework Statement Suppose a relativistic particle with spin 1/2 at rest. Show that if we apply an electrical field at t=0 there's a probability fot t>0 of finding the particle in a negative energy state if such negative energy states are assumed to be originally empty. Homework Equations...

Homework Statement The arch y= sin(x), x is in [0, pi], is revolved around the line y=c, where c is a constant in [0, 1], to generate a solid... Anyway, then I have to represent the volume of the solid as a function of c and other stuff. Homework Equations The Attempt at a Solution...

-1=\sqrt[3]{-1}=(-1)^{1/3} = (-1)^{2/6} = ((-1)^2)^{1/3}=1^{1/3} = 1 How can this be?

Homework Statement Graph the following inequality in the complex plane: [FONT="Courier New"]|1 - z| < 1 2. The attempt at a solution In order to graph the inequality I need to get the left side in the form [FONT="Courier New"]|z - ...| [FONT="Courier New"]|1 - z| < 1 |(-1)z + 1| < 1 |-1(z...

http://img707.imageshack.us/i/electronicsoscillator.jpg/ Dont know where to start for showing voltage difference at input is zero, suspose its something to do with non idealities of the op amp? For the oscillator question , kinda know how its works; there's positive saturation giving...

greetings, consider a wire which is subjected to AC supply.now consider a point X anywhere on wire. now what will be the potential of that point during the positive and negative halfcycle of sinusoidal AC?what will be the direction of current? thanks

I've seen the use of a negative exponent in the books and articles I've been reading lately, and I was wondering exactly what it meant. Such as 300 cm-1, where cm has a -1 as the exponent. (Dont know how to type that out.) What does it mean?

Homework Statement consider a circuit expressed by v(t)= 100cos \omega t and i(t)=2cos(\omega t+\pi / 3) . Find the reactance.Homework Equations Z=\frac{V}{I} = R+jXThe Attempt at a Solution Z=\frac{100}{2\angle \pi /3} = 50\angle -\pi /3 = 46 - j19 Does the negative imaginary part mean...

Hi In (quantum) optics, many authors state that the field amplitudes satisfy E\left( { - \omega } \right) = E^* \left( \omega \right) But how is it that one can prove that this is correct? I have never seen any book do this,

Negative permeability of split ring resonators(SRR) is obtained between the resonant frequency and the Plasma frequency of the SRRs, then what is the meaning 'eigenfrequency' of split ring resonator(SRR). Is eigenfrequncy is that 'frequency' at what negative permeability occur ??

Hello; You can have positive integer derivatives, such as this: \frac{d^{2}}{dx^{2}}(x^{2}) = 2 You can have fractional derivatives too; \frac{d^{\frac{1}{2}}}{dx^{\frac{1}{2}}}(x) = \frac{2\sqrt{x}}{\sqrt{\pi}} But what about negative derivatives? \frac{d^{-2}}{dx^{-2}}(x^{2}) Or even...

Hi can anyone tell me if I had the following readings how could I calculate kw or kwh. The readings were taken from an electricity meter which logged the values every 15 minutes and the values below are what were recorded in the first 15 minute period; A+ Energy Total = 3920Wh A- Energy...

Homework Statement http://img33.imageshack.us/img33/8751/49753333t.jpg Problem #2 [PLAIN][PLAIN]http://img121.imageshack.us/img121/5574/35712633.jpg My question is, why do they take positive x0? Shouldn't it be negative since it is that amount of x displacement away from the spring?

Homework Statement 1. A heat engine operating between 200°C and 80.0°C achieves 20.0% of the maximum possible efficiency. What energy input will enable the engine to perform 10.0 kJ of work? Homework Equations e =1- Tc/Th W=e*Qh The Attempt at a Solution I got the answer but I...

I have question. Want to know time dilation for clock at negative coordinate in moving frame to reach origin of rest frame. Let's use P' = ( -7/8ls,0,0 ). Use v =3/5c, then γ = 5/4. ls is light seconds. Now, do you apply Lorentz Transforms like this t' = ( t - vx/c² )γ But, we do...

I wonder whether Dirac explanation of paradox of negative energy solutions of his equation is viable. Of course this paradox is absent in QFT but if we treat Dirac equation as an equation for wave function of electron the negative energy solution are a puzzle. Acording to Dirac we don't...

Homework Statement We recently did a lab in my physics class where we looked at the conservation of energy of a ball on a roller-coaster track. We got the data as seen in the picture below http://tinypic.com/r/168zx2s/7 the question now is why is there negative energy loss, is this...

Homework Statement This is the conservation of energy in the absence of external forces ΔKE + ΔPE + ΔTE + ΔU= 0 TE is friction, U is other internal energy, like the spring So expand and disregard U and TE for a moment ½m(v² - v₀²) + mg(h - h₀) = 0 Now comes the...

In an inverting opamp let the output be feedback to inverting input through a feedback resistor Rf. We write the direction of flow of current from input terminal to output terminal in the feedback resistor Rf. But if this direction is correct then how can we say that input is fed back?? it seems...

This has been bothering me, since I just realized I've never really thought about it. What's the correct sign of gravity? Of course, it's supposed to be negative, since it points down, but in GPE (mgh) it seems to be positive. GPE is positive above the zero level, and so g must be positive as...

I asked my prof a question, and this is what he answered "Vectors can't be negative; only components can be negative. (Only scalars can be negative, and components are scalars.) Vectors can be only zero or non-zero" can someone explain this to me? I have the feeling that everything I've...

Homework Statement Ok so the question is, is the state u(x) = Bxe^[(x^2)/2] an energy eigenstate of the system with V(x) = 1/2*K*X^2 and what is the probability per unit length of this state.Homework Equations The Attempt at a Solution So the way i did this was, to find if the state is an...

why do positive and negative charges attract each other?

Q.)A stone is dropped from a balloon going up with a uniform velocity of 5.0 m/s . If the balloon was 50m high when the stone was dropped, find the time after which the stone will be at ground. Ans)On solving this, we can get a quadratic equation in 't'[time]. The 2 values of t was then found...

A graph shows the Force of a spring (y axis) against Displacement (x axis) in a linear function. An obvious point for the gradient is the point (0.5 metres, 140 Newtons). What is the spring constant and how much energy is stored in the spring when it is compressed by 0.5 metres? Hope the...

Homework Statement This maybe a silly question to ask, but it did spend the silly me a night googling with no luck. I am doing a Matlab asgn that I need to add some normal random noise to an image. Homework Equations Here is my code...

Well I'm 25 years old, and am currently in the middle of a major career change, going from consulting to physics. Now for me my age isn't a problem, i feel motivated and am ready to bust my :blushing::blushing::blushing: for this. However, I've been wondering if it could be a problem for...

hi, does anyone know why vacuum energy has negative pressure? is it only experimental or it is theoretical too? i also wonder if the negative pressure of the Casimir effect is absolutely negative or if it is relatively negative relatively to the rest of the laboratory? i would be...

Are there any negative probability or negative energy photons?

in 2's complement the negative of 1 is "111". but it also signifies 7 in decimal. how does this -ve 1 is differ from 7? thanks

Homework Statement If you dive into the water does it do work on you? Positive or negative? Homework Equations The Attempt at a Solution I think I know this one, it is negative work because he is pushed up from resistance, but continues to go down.

I want to plot a line in mathematica with a negative slope by setting it's starting point, length, and slope but i couldn't figure out how to do it. example: A line "AB" has a starting point (40,0) has a length 10 has an angle 127 degrees between x axisIn MATLAB i can do this with %% k =...

I know that a Schwarzschild metric cannot have negative mass parameter. But what about regions? It is possible to have negative mass parameter between two spherical shells? If not, what is the argument?

Just as the title states, I'm working on a problem and have come to negative infinity divided by infinity. Is this an indeterminate form? I know that if they are both positive it is indeterminate, but I can't remember if one being negative makes a difference.

How can I find probability p that maximized P(Y = y*) when Y has a negative binomial distribution with parameters r (known) and p? I've just reduced the problem with some algebra, but other than guess-and-check I have no rigorous way to solve this problem.

Hello everyone! This is my first post, and I regret that it has to be a question that is so elementary. The Problem: I am in an introductory engineering course in which we were divided into teams and told to construct a catapult. Rather than follow design requirements, and despite my...

Hey people, I searched by this question in the forum but don´t found the answer. I have a simple doubt about this theory in mechanic. The question is: There is negative force? I know that when I am working in math with a vector that represents a force I can use the negative signal to...

Ball launched off a cliff at negative angle... Homework Statement So a ball is launched off a cliff 60 meters high It is thrown at -15 degrees horizontal, and lands 120 meters away. Find the V-initial, V-final, Time in air, and Angle at which it hits the groundHomework Equations inverse...

hi, which phenomena is known in quantum mechanics to cause a negative pressure? as far as I know, the vacuum energy of the time energy uncertainty has a very low energy density but it should have a positive pressure because it pushes and not pulls, am i right? so which phenomena actually...

hi, which phenoma are known in quantum mechanics to cause a repulsive gravity due to negative pressure? as far as i understand, the vacuum energy of the time energy uncertainty has a very low energy density but it should have a positive pressure because it can only push and not pull. am i...

Under what conditions and how will negative oxygen ions react with hydrogen and hydrocarbons (such as methane or gasoline)?Does it require some catalyst or should be burned together? What is a way to harness spare electrons from oxygen when water is formed?

Cant seem to come up with the answer for portion BA car is traveling to the left, which is the negative direction. The direction of travel remains the same throughout this problem. The car's initial speed is 27.2 m/s, and during a 3.90-second interval, it changes to a final speed of (a)39.0 m/s...

Homework Statement There's a 75 kg passenger in an elevator a. what is the passenger's apparent weight when acceleration is zero? b. what is the passengers apparent weight when acceleration is positive? c. what is the passengers apparent weight when acceleration is negative? Homework...

I watched a video there about cathode ray tubes and the guy in the video demonstrated the negative pole of a magnet deflecting the beam and the positive pole attracting the beam. I know that moving electrical charges create magnetic fields but I didn't know their magnetic fields always deflect...