Negative Definition and 1000 Threads

Dear all, How to deal with negative integer factorial functions? I mean what expression formula can be substituted for this?

I understand that taking logs of a negative number isn't possible because no number to any power produces a negative number. But why not a negative base? Say, log-10(100) = 2. Rewritten, -102 = 100, which is accurate. You could suggest that you may as well just ignore the negative because -x2 =...

Homework Statement (This is a photocopy of the page, no real books were defiled in the process of studying :P) Homework EquationsThe Attempt at a Solution In an example in my book, a problem reads that a car is moving in the positive x direction, the initial velocity is 15m/s and it takes 5...

What happens when negative plate of a charged capacitor is connected to positive plate of another charged capacitor and vice versa. ?

Homework Statement If the vector B⃗ has a magnitude of 45.0 m and makes an angle of 60.0 ∘ with the +x axis, the vector -B⃗ choices: 1. has a magnitude of 45.0 m 2. has the same direction as B⃗ , but a magnitude of − 45.0 m 3.makes an angle of − 60.0 ∘ with the +x axis 4. has the opposite...

1.Homework Statement The wave function for a wave on a taunt string is: y(x,t)=(0.350)(sin(10(π)(t)-3(pi)(x) +(π)/4) where x and y are in meters and t is in seconds. If the linear mass density(μ) of the string is 75.0g/m, (a) what is tha average rate at which energy is transmitted along...

Hello, I'm brand new to this site. I have a number of questions that I can't get answered by anybody. I want to some how create negative pressure under the car to suck the bottom of a car down using Vacuum fans (like the 1970 Chaparral 2J Can-Am racing car ("sucker car"). I has some basic...

I'm a little confused over what constitutes negative and positive energy. I've heard it said that we have a zero energy universe because the mass of the galaxies, etc. counts as positive energy which is exactly balanced out by gravity, or the gravitational potential, which counts as negative...

Hello All, We are trying to convert a vacuum leak test for medical devices (catheters) from a syringe based test to a pump based test. The current guidelines call for purging air from the ID of the catheter under test with water (~1mL). The distal end of the catheter (tube) is blocked and the...

The following is invalid, since the operation is not defined when ##a, b < 0##: ##\sqrt{-1}\sqrt{-1} = \sqrt{(-1)(-1)} = \sqrt{(-1)^2} = \sqrt{1} = 1##. This is not correct, because ##ii = -1##. This shows that ##\sqrt{a}\sqrt{b} = \sqrt{ab}## is invalid when ##a, b< 0##. However, say we have...

Since lnx is defined for positive x only shouldn't the derivative of lnx be 1/x, where x is positive. My books does not specify that x must be positive, so is lnx differentiable for all x?

This isn't actually a homework problem, but it is an example in a my textbook that I have a question about... imgur link: http://i.imgur.com/2OglMH4.png Ok, I wanted to clarify some things. I understand that current flowing from a positive terminal to a negative terminal represents a...

How would we define positive and negative work in terms of energy? When the force and displacement are in opposite directions, we say the work done by the force is negative. When the force and displacement are in the same direction, we say the work done by the force is positive. However, how we...

I would like to know the maximum voltage that a metal sphere can hold from applying negative charge to it. My thoughts are that the maximum voltage is the breakdown voltage of the surrounding medium (air in this case). I assume that at that voltage, electrons would arc from the sphere to the...

Homework Statement What is the volume of a solid formed by the area trapped between y= -x^2 and y= -2x rotated 360° around x-axis? Homework Equations V = ∫A(x)dx The Attempt at a Solution y=y -x^2 = -2x x^2 -2x = 0 x(x-2) = 0 This means that the two functions cross at x = 0 and x = 2 From x...

Homework Statement I was just wondering whether the following notes I took on work in physics are accurate? Or have I got my understanding wrong? Note on friction Following from the example of the dragging object above… The object stops because it loses kinetic energy due to friction. How...

Homework Statement Determine the tension cable A and B and the x , y , z reaction of the ball and socket joint at C . Homework EquationsThe Attempt at a Solution I let the reaction of ball and socket joint at C = Fx , Fy and Fz Sum of force in z direction : TA +TB +FZ= 400 Sum of force in...

I am an undergrad working in biophysics research, and I was hoping you guys may have input on a simple but strange problem I'm facing. I don't know if this is appropriate for this forum, but it is not an especially specialized or complex problem and I am desperate. I am currently conducting...

Homework Statement Arg z≤ -π /4 Homework EquationsThe Attempt at a Solution I'm confused whether the answer to that would be more than -45° or less. Should the approach to arguments be the same as in negative numbers?

I'm having problem understanding why negative angle of cosine is a positive value but negative of sine is a negative sine angle?why is this so?can someone please help me with this confusion? Thanks in advance!COS(-angle)=COS(angle) Sin(-angle)=-Sine(Angle)

Homework Statement Hi all! The problem is - 'find the condition that all roots of $$f(z)=az^3+bz^2+cz+d=0$$ have negative real part, where $$z$$ is a complex number'. The answer - $$a,b,d$$ have the same sign. Homework EquationsThe Attempt at a Solution Honestly, I have no clue about how to...

Hi, I am working on a video capture project in which i am videoing the projectile of a ball that is being thrown in the air and trying to fit it to a curve for the expected trajectory of a projectile with quadratic drag.I am running into the issue that in order for my expected trajectory to fit...

Homework Statement How many non-negative integer solutions are there to the equation x1 + x2 + x3 + x4 + x5 < 11, (i)if there are no restrictions? (ii)How many solutions are there if x1 > 3? (iii)How many solutions are there if each xi < 3? Homework Equations N/A The Attempt at a Solution...

Hi everyone, I've encountered a curious problem I just can't figure out, and any input would be much appriciated!This is a personal project I'm working on, and as far as I know, there is no one else working on exactly the same. However, the computational study of critical phenomena is quite...

Homework Statement I was given the Brayton reverse cycle and asked to prove that the total heat is negative (hence the heat pump cools the system). I was to assume that all the steps are reversible. Homework Equations An ideal diatomic gas. 1st step: adiabatic compression. 2nd step...

An exercise in my text requires me to (in MATLAB) generate a numeric solution to a given second order differential equation in three different ways using a forwards, centered and backwards difference matrix. I got reasonable answers for \vec{u} that agreed with each other (approximately) for the...

I know this has been asked before: "Why is there a negative in the Lagrangian: L = T - V" I have read the answers and am not happy with them so I tried to formulate my own justification and now ask if anyone could comment on it? First, I am not happy with those who say "Because it works and...

These questions shows my lack of understanding of the expanding universe specifically the Friedmann equation. Here is a quote from Brian Greene (The Fabric of the Cosmos, page 273): “The early universe provided an arena in which gravity exerted its repulsive side with a vengeance, driving every...

Homework Statement What is the acceleration of a body which is moving in opposite direction(assuming negative velocity) and is speeding up? Homework Equations acceleration=the rate of which an object changes its velocity The Attempt at a Solution In my opinion, an object moves with a negative...

So, I'm to understand that "0 - -a = a" and I can understand this, in the context of say, being at an arbitrary reference point called "0" and then on a 2 dimension Cartesian graph of + shape and the operator "-", which can mean to reverse (so turn around 180 degrees) and then the second minus...

Hello, I have been reviewing my textbook lately, and I came across a rather paradoxical statements. all of the convergence tests in my book state that the terms of the series has to be positive. However, when I solved this power series ∑(-1)n-1(xn/n), I found that it converges for -1<x≤1, but...

Homework Statement https://www.google.se/search?q=f%C3%A4ltlinje&rlz=1C1_____enSE665SE665&espv=2&biw=1366&bih=643&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMI9dTNgquLyQIVhJIsCh1NxQZU#tbm=isch&q=physics+field+lines&imgrc=rKecBAfLOMsOoM%3A Why are the field lines on the positive atom pointed...

Homework Statement The aim is to find a solution for the scale factor in a Robertson Walker Metric with a scalar field and a Lagrange multiplier. Homework Equations I have this action S=-\frac{1}{2}\int...

Homework Statement In the following question, in the solution, why is it that when they calculate the gravitational potential energy at point 2 (impact with spring), it is negative? I know that if both the force and displacement act in the same direction, then the work done should be positive...

Homework Statement The problem I have is that we are asked to show the complex relative permittivity of a good conductor is erc = 1 + i(sigma)/(omega*epsilon_0) where sigma is the conductivity and omega is the frequency of an electromagnetic wave in the medium. This is fine, I calculated it...

Homework Statement An error matrix is in the form, has a characteristic equation: ## CE: s^2 + 120s + 7200 = 0 ## A state variable feedback system is described by: ## A_F = \begin{bmatrix}0 & 1 \\-616.8 & -40 \end{bmatrix} ## ## B = \begin{bmatrix}0 \\ 1 \end{bmatrix} ## ## C =...

Disclaimer: not sure if this is actually the most appropriate forum, but it is a question inspired by my work on a homework question...I'm happy for a moderator to move this to a different forum. (But General Physics states: NO HOMEWORK/COURSEWORK QUESTIONS HERE) 1. Homework Statement Ok...

What is meant by a negative distance on a sinogram in PET imaging? http://frcrphysics.com/wp-content/uploads/2014/05/PET-sinogram.jpg In this image displacement can be +ve or -ve. What would a -ve distance be? Thanks

Homework Statement Homework Equations See above The Attempt at a Solution In the solutions guide for problem 71, if a charge is negative (look at the -1.5 C charge), it will be negative in the equation for potential energy (last step where multiplication brings 1.5J. On the other hand...

In the torque moment diagram of 4 stroke engine, there is a negative loop during suction stroke. Many books state that it is due to the higher atmospheric pressure. But, I do not understand the concept. Please help me understand why there is a negative and positive loop during suction and...

Homework Statement An amount of work equal to 1.5 J is required to compress the spring in a spring gun. ? Homework Equations Wtotal = change of KE[/B] The Attempt at a Solution W=ΔKE=(1/2)m(Vf² - Vi²) It sounds like the Vf >0 and would be maximum after the spring is compressed hard and...

Homework Statement Consider the feedback loop involving Clouds, Rainfall and forest area. All the relationships represented in this figure show positive couplings between the components: Forest area is positively coupled to rainfall, plant evapotranspiration is positively coupled to forest...

Homework Statement Train goes 20 m/s Brakes cause a = -1 m/s2 Displacement at t = 40s ?Homework Equations v = 20 m/s a = -1 m/s2 t = 40s The Attempt at a Solution image upload no limit It seemed like this formula fit perfectly. It had all of the known variables and the one unknown neatly out...

Homework Statement [/B] Find the position vector of point P if P divides AB in the ratio 5:-2 given A (-1,6,4) and B (4,1,-1) The Attempt at a Solution The only trouble I have is to understand the question... Does it mean something like A------------------>B<----------------------P...

Why potential at a point can only be obtained by supposing/assuming a positive test charge there? For example There was a question In figure two points A and B are located in a region of electric field.,The potential difference ##VB##-##VA## is 1-positive 2-Negative 3-zero 4-none of the...

I'd like to know your views. Is it too good to be true? Or is there any obvious blunder?http://arxiv.org/abs/1509.07854 NUT wormholes Gérard Clément, Dmitri Gal'tsov, Mourad Guenouche (Submitted on 25 Sep 2015) We show that supercritically charged black holes with NUT provide a new setting for...

I am missing something basic here. In https://en.wikipedia.org/wiki/Negative_energy, it is stated that "a universe in which negative energy dominates will either expand indefinitely or..." But gravitational potential energy is negative, so if I make the substitution, I would get "a universe in...

Hi , this may been asked quite a bit times but I can't really find a solid answer for this. Do we have to include negative signs during calculations for vectors or scalars? I have been told by someone that for vector quantity calculations such as Force we do not include the negative sign or...

Is there something wrong with negative probabilities per se? I don't what to hear that they are "unphysical" because it is not clear what reality is. Can negative probabilities (or probabilities > 1) be somehow consistent with macroscopic realism => not causing any macroscopic weirdness (no...

Homework Statement http://imgur.com/RlIdmFh http://imgur.com/3dnLK3m Homework Equations |x| = -x? The Attempt at a Solution I'm trying to make sense of this definition in my book because they are trying to prove the triangle inequality(second link), yet it keeps saying that the absolute value...