Negative Definition and 1000 Threads

Is there any difference between the meaning of the equation W=-ΔU and the meaning of the statement that potential energy of system is always negative when the reference point(zero point) is taken to be located at infinity or do they both convey the same message?

Hello... Can the cosmological constant become so rigid as to resist the 120 magnitude quantum contribution? Where is the mathematical terms for it in GR EFEs? is the effect like contraction instead of expansion? Because the 120 magnitude quantum contribution should immediately warp spacetime...

Homework Statement Two baseballs are set in motion from the top of a 5 m tall tower. One is thrown straight down toward the ground with an initial velocity of 20 m/s. The second is thrown straight up toward the sky with an initial velocity of 20 m/s. How do their velocities compare when they...

Homework Statement Heat engines at negative temperatures. Consider using two heat reservoirs to run an engine (analogous to the Carnot cycle of chapter 3), but specify that both temperatures, T_hot and T_cold, are negative temperatures. The engine is to run reversibly. (a) If the engine is to...

I have read that the apparent weight of a person in a lift accelerating with acceleration 'a' downwards is given by: W = m(g-a) where 'm' is his mass so if a>g, then one feels negative apparent weight. But, it is also true that one becomes conscious of his weight only when he gets a reaction...

Hello everyone, So I am doing this EMC course and got to a section about cable shielding. It was suggested that the best way is to have a 360 connection to the chassis and to connect the ground of the PCB to the chassis as to provide a better return path for the current. It has been suggested...

Hello. Casimir effect allows to create negative-energy-density (NED), but ONLY SMALL AMOUNTS of it. I wonder if physics generally allows for the existence of negative energy in large quantities. I think that if the negative energy can be produced in small quantities, it can also occur in larger...

I am solving for the square root of a complex number, namely: ##\sqrt{5 -12i}## Let's assume for brevity's sake that I already have the solution ##3- 2i##. This is fine and well, but the book that I am reading goes on to say that "##- (3 -2i)## is an equally valid solution, since there is no...

I've seen in many equations of physics that whenever we demonstrate an attraction force we tend to use a negative sign before it,why is that? In case of coulomb force it makes sense because when the charged particles are of opposite signs a negative sign is sure to be appeared.But why do we...

I know its very basic but still. From the school level we thaught that positive attracts negative. But i still don't know what is reason behind it. Why this work on atomic level? What is the reason behind the electrostatic attraction?

I'm trying to add flight physics to a 3d game. When I try to calculate drag I sometimes get a force that pushes the aircraft backwards if I make the wingspan very large (for example). I have set up a simple scenario: A flat rectangle sheet falling down due to gravity. If I make the gravity...

Why doesn't The Feynman Lectures consider the possibility of negative ##\alpha## when it says that ##e^{+2\alpha\rho}## is a rapidly increasing exponential (just below http://feynmanlectures.caltech.edu/III_19.html#mjx-eqn-EqIII1923) ?

Howdy! How do I build a small low-voltage ion generator? The simplest possible design; we'er talking AA batteries here with step-by-step instructions... Any links or advice would be graciously accepted / appreciated. Here is a youtube video of the thing I want in case I'm not describing it...

Recently I learned some communication theory, which uses negative frequency, what does negative frequency means? So I checked textbook, found the negative frequency comes from the Fourier transform, which comes from the euler formula, e-jx=cosx+isinx, or another form cosx=(ejx+e-jx)/2, then any...

Homework Statement Homework EquationsThe Attempt at a Solution Negative ∆H means that the product is more stable. Change from solid to gas requires energy so cancel out A and C. Reaction D doesn't make sense. The products of reaction B and E are more stable than the reactant because there is...

When an alternator is supplied with a 3-phase voltage and its rotor is rotated in opposite direction to that of the stator rmf, the ratio phase voltage/phase current is the negative sequence impedance of the alternator. My understanding of this is as follows: When rotor is rotated in opposite...

Hi, i'm looking for an explanation to this answer of a past paper that I'm doing, it's from OCR (A level) G485, question 1 b ii) the question on top, and answer on bottom i don't understand why would the point experience a negative electric field strength when it's getting closer to a...

http://imgur.com/BNQPAQa I'm missing something. Why does x+1/x suddenly become x-1/x2? I get that they moved the x to the top, subtracted the -1-1, but does that exclusively set the fraction negative all on its own ? I've computed it by hand. 1-2 comes out to be 1... So why is it negative... ?

Hello. The first image is the question, the second image is from the solutions manual. I don't understand why these answers are negative. Anyone have a clue?

Under what conditions would negative buckling (B^2) be possible?

Hello, Following Hooke's law, the force applied by a string on an object attached to one of its ends is F = -kx But here is my question : if we consider the equilibrium coordinate x=0 of a horizontal string, and the string is stretched until its end reaches a coordinate x1>0. By applying hooke's...

We recently performed one experiment regarding measurement of negative sequence impedance of an alternator(unloaded) in our lab session. The alternator was star connected and we shorted Y and B phases together, leaving R phase open(an L-L fault). How does this arrangement generate negative...

Hello to all members! I heard on a documentary about general relativity and singularities that "energy is locally never negative". However, I was not able to get grasp the meaning of this term. Could someone explain to me the meaning of this term in the framework of general relativity. I really...

The Earth has a net negative charge whilst the Ionosphere has a net positive charge, this has been known for well over a hundred years now. My question is about the negative charge of the Earth, are the free electrons on the Earth's surface stationary? are they whizzing around in the Earth in...

Hawking and others have claimed that there's a negative energy associated with gravitation that makes the universe's total energy balance -- including all the energy in all the mass in all the matter in the universe -- zero. But there was no such thing as negative energy in any type of physics...

I am having trouble with this program with negativeCntr . Any one explain what i am doing wrong and guide me please. [CODE]#include <iostream> #include <cstdlib> using namespace std; class IntNode { public: IntNode(int dataInit = 0, IntNode* nextLoc = 0); void InsertAfter(IntNode*...

Homework Statement Homework Equations F = ma The Attempt at a Solution [/B] I already have the solution, however, I have a few questions. 1)In the solution they have taken m2's acceleration relative to the ground to be a0-a downwards. However, if a>a0, then wouldn't the acceleration...

Or basically anything that isn't a positive integer. So I can prove quite easily by induction that for any integer n>0, De Moivre's Theorem (below) holds. If ##\DeclareMathOperator\cis{cis} z = r\cis\theta, z^n= r^n\cis(n\theta)## My proof below: However I struggle to do this with...

Homework Statement Homework Equations The Attempt at a Solution I am not really sure how to do this problem. How can I convert from db to linear terms just given db? Don't I need more information? For do I have to do a system of equations or something using the Power gain =...

in some books it is written that it is because of gravity but i can't understand how gravity can cause such a effect

Good morning, How do we prove that the number zero is a negative or positive number?

https://en.wikipedia.org/wiki/Negative_refraction http://www.cmth.ph.ic.ac.uk/photonics/Newphotonics/pdf/DRS&JBP_final_.pdf Supposed the nature of light is altered and light itself cause negative refractive index in normal lenses.. what would we see with our eyes, lenses, binoculars? What...

I am aware of what positive and negative polarities are but what specifically causes the distinction between positive and negative polarity?

Every thermodynamics cycle needs to do negative work to the environment, which lower its total positive work. For example, in Carnot cycle, the most efficiency possible: 1/ Engine receives heat from hot reservoir, expands and do positive work to surround 2/ Surround does work to engine...

I've already completed the first question, but with number two, it's a different case. Here's my attempt: \frac { d{ v }_{ y } }{ dt } \quad =\quad -g\quad -\quad \beta { v }_{ y }\\ \frac { d{ v }_{ y } }{ -g\quad -\quad \beta { v }_{ y } } \quad =\quad dt\\ \int { \frac { d{ v }_{ y } }{...

Given the following pattern. $$(-1)^{0}=1$$ $$(-1)^{1}=-1$$ $$(-1)^{2}=1$$ $$(-1)^{3}=-1$$ $$(-1)^{4}=1$$ $$(-1)^{5}=-1$$ $$(-1)^{6}=1$$ $$(-1)^{7}=-1$$ $$\ldots$$ In words, we might say that the power of a negative number is: Positive for even exponents. Negative for odd exponents. How...

Just wondering why to use negative hydrogen H- ion in spallation neutron source. I read the literature through http://neutrons2.ornl.gov/facilities/SNS/works.shtml , still not yet get the answer. If directly use proton, then still easy to accelerate, and no need to strip off the unwanted...

Homework Statement We were asked to use a Hall probe (in units of Guass) to measure the magnetic field strength in 0.5 cm increments away from a wire carrying 4 A of current. As we got further and further away from the wire our B value got smaller and smaller. Eventually they became negative...

For Hooke's Law, why is there a negative in F = -k*x? Is it because k is the reaction force against the force applied on the spring and not the force pushing or pulling on it? For example, let's say that the origin is set where the spring ends when it's in equilibrium with no forces applied to...

In the Hamilonian for an H2+, the kinetic energy of the electron (KE of nucleus ignored due to born-oppenheimer approximation) has a negative sign in front of it. I understand the signs for the potential energy operators but not for the KE apart from the strictly mathematical point of view. Can...

I'm currently completing an Atwood Machine Experiment with two 100g weights on either side of the pulley, with a variance in weight created by attaching dimes and pennies to either side of the weights. The point of the experiment is to validate: (m1 – m2)g = (m1 + m2 + I/R2) Homework Statement...

https://www.mpg.de/research/negative-absolute-temperature A temperature below absolute zero Atoms at negative absolute temperature are the hottest systems in the world January 4, 2013 What is normal to most people in winter has so far been impossible in physics: a minus temperature. On the...

Hello, I want to know if there exist any result in literature that answers my question: Under which conditions on the real valued matrix ## R ## (symmetric positive definite), the first argument results in and guarantees the second one: 1) for real valued matrices ##A, B, C,## and ## D ## with...

Hi, I'll start by offering some context to my question. I am a mechanic by trade, and have a bachelor of technology in motorsport engineering. I have a friend who is an electrician by trade, and he likes to work on his car in his spare time. In my line of work I only deal with 12V/24VDC...

Hi everyone, I've been seeking the answer to this question for a long time. I've looked at posts like... https://www.physicsforums.com/threads/op-amp-transient-state.855512/ and https://www.physicsforums.com/threads/how-does-negative-feedback-in-an-op-amp-work-conceptually.584881/ ...but I...

Hello all and thanks in advance for your contributions. I am calculating how much weight it will take to keep a car on the floor of a 5' deep pool. The engine and transmission have been removed as well as the hood and trunk. The remaining body weighs 2,000 lb. The cab will be sealed air...

Homework Statement In the diagram below, each division on the horizontal axis (the displacement s) is 0.10 m while each division on the vertical axis (the electric potential V) is 1.0 V. What is the electric field component along the displacement axis s in each of the regions specified below...

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...