Negative Definition and 1000 Threads

Using the potential energy formula -GMm/R^2 I understand that the maximum potential energy is 0. But what is the significance of the potential energy as it approaches negative infinity? I am not sure how exactly to word this, but I cannot seem to grasp the what negative potential energy tells us...

Suppose that you have N = \left(\frac{\partial U}{\partial \mu}\right)_{S,V} < 0, supposedly the number of particles, even though the actual number of particles is greater than zero. This means that you can have, in a system subjected to a grand canonical ensemble, less than 0 particle for...

Background The teacher doesn't teach we just do activities and have whole chapters worth of 20 mini assignments due every few days. Yes I did read the book. 1. Homework Statement Determine the signs (positive or negative) of the position, velocity, and acceleration for the particle in...

The fact that energy in a laser can propagate without much loss over long distances is quite shocking ! It's a renowned fact that energy is dissipated when propagation takes place through any medium... (I'm fully aware that laser is an exception) But I have quite a difficult time understanding...

Hello. I really don't get a concept of a way to generates negative voltage as a one of the supply voltage to typical OP-AMP. (Operational Amplifier) The output voltages is supposed to swing to more than 10 V thus supply voltages to OP-AMP should be +15V and -15V. I'm thinking of supply these...

HI all How can Michelson itself predicted contraction of length and Einstein about constancy of light from negative result of MM experiment. forget about existence of ether, light speed always same in moving frame of reference and importantly in any direction so how can one except shift in...

Hello, I was looking for some sort of chip/IC that would accept a digital input of say 4-5 bits and that would adjust an output current. I am looking to have a +/-3.3mA current applied to a resistive load. It would also be helpfull (for testing purposes) if I could adjust the inputs so that I...

I was wondering if scientists or mathematicians have any use for complex numbers involving negative roots of I as in i=(-1)^(1/2). but my question is more what would be (-1)^(-1/2)?

In the range equation, is the value of g ever taken to be negative? dx=Vi^2/g x sin 2 (theta) Basically my question is where the y displacement is 0, and we are able to use the range equation, will the value of g ever be negative, and if so, when? I know Vi is simply magnitude and not...

Hi, I'm confused and need some help. What I thought happens in a battery is that the anode (the positive electrode) attracts the anions, it then goes through oxidation by taking the electrons and those electrons move through the closed circuit to the cathode and reduction is done. If that is...

Dear PF Forum. I saw once that sinh-1(x) is arcsinh(x). The reverse of sinh Why not sinh-1(x) is 1/sinh(x)? While x-1 = 1/x Is it just a 'convention' between mathematician? Thanks.

I'm reading through Sparknotes' explanation of the equation: U = -Gm1m2/r "Off the surface of the Earth, there’s no obvious reference point from which to measure gravitational potential energy. Conventionally, we say that an object that is an infinite distance away from the Earth has zero...

I originally posted the following question on physics.stackexchange, but no one was able to answer it. I did find this answer on PhysicsForums, but I was already aware of the oscillation of electrons in response to an external electric field. What is the physical cause behind a material having...

Hello. I've studied the golden rules of the feedback OP-AMP and applying this to voltage follower shows that voltage gain (Vout/Vin) is 1. Thus, Vout should eventually follows Vin when Vin suddenly changed. I've tried to follow this process for clear feeling by drawing pictures as shown in the...

Homework Statement Express (-1)1/10 in exponential form (My first time posting - I hope I got the syntax right!) Homework Equations The Attempt at a Solution [/B] I got the solution, it's ejπ/10, but I'm not sure why. Here's my work: (-1)1/10 = (cos(π) + jsin(π))1/10 = cos(pi/10) +...

Why does negative resistance indicate ballistic transport?

Hi, I read on a previous post that to calculate the exponential of a large negative number I use the formula: e-r=10(-rloge) This is just a quick question but it it meant to be a log 10 or natural log and also is it meant to be loge0 or loge1 Thanks in advance

Homework Statement Hi, with regards to the negative zero error , do we read the vernier scale from the left or from the right? In this case, should it be -0.04cm or -0.06cm? Thank you !

Someone told me there is no such thing as negative acceleration and I did not believe them. They said its called deceleration and is not considered negative acceleration. Is this true and why?

How does one prove ##\sin{(x+y)} = \sin{x} \cos{y} + \cos{x} \sin{y}## for all real ##x## and ##y## (not just for ##[0, \frac{\pi}{2}]##? Almost every "geometric proof" I see for formulas like the one I mentioned above, or results such as ##\lim_{x \rightarrow 0} \frac{\sin{x}}{x} = 1##, places...

Hi, I have a question regarding the forces applied on an object that create the torque. I understand that the resulting torque is pos if the object turns counter clock wise and is neg if it turns clock wise and that you can also use the right hand rule to find the direction of the net torque...

Homework Statement I am working on a problem that states the following: Imagine an infinite straight wire carrying a current I and uniformly charged to a negative electrostatic potential Φ I know here that the current I will set up a magnetic field around the wire that abides to the right...

Hello, I know that a negative logarithm is undefined. But I am faced with an equation like this: -1 x (-2)^(n-1) = -16777216 I divided it by -1 to give (-2)^(n-1) = 16777216 And then took logs to get (n-1) log(-2) = log 16777216 Since I can't work out the log of a negative number, what do I...

Hello, I have some mathematics background but little to no physics background. I am very interested in physics and am beginning to learn about relativity. Upon exploring the derivation of the Lorentz Transformation equation I noticed something that confused me a little. Again, I don't have much...

Shyan submitted a new PF Insights post Negative absolute temperatures Continue reading the Original PF Insights Post.

For this function: $$\lim_{{x}\to{-\infty}}\frac {x} {\sqrt{x^2}} = -1$$ Why is this correct? If x is equal to -1, for example, -1 square is 1. And the square root of 1 is 1. So should the answer be 1?

Homework Statement (See image) 2. Homework Equations C=Q/V The Attempt at a Solution Part a took a while but I now understand that the electrons gather on the right plate of the 2μF capacitor and on the right plate of the 4μF capacitor. This imparts a negative charge of 133μC on each...

Homework Statement My teacher keeps saying we can't have negative times because they don't exist and when I do these questions I get negatives and can't understand them at all, can someone help me? 1. How long does it take to slow a car from 10m/s to rest at a rate of -1.75m/s^2? 2.How long...

Hello, I heard that theoretical particles that have negative mass (techyons) are predicted to tend to speed up to infinite, if their energies are low enough. I don't understand why infinite speed instead of 2c (double the speed of light) are predicted? Note: I don't know whose/which theory it...

Hello, I work in energy auditing. I noticed a lot of the standards I am given for lighting, etc are in Watts per negative square meter: W·m-2. Does anyone know what this means? Why isn't it just in W·m2 ?

Homework Statement I have to make a program that would end when entered a 0 and print out negative numbers and even numbers separately but what I have so far is not working. The Attempt at a Solution numbers = [] negative_numbers = [] while True: number = input("Enter a number: ")...

Homework Statement Calculate ##R_S## given the expression: $$A_v = - \frac{g_m (R_L || R_D)}{1 + g_m R_S}$$ The parameters ##g_m = 1.292 \frac{mA}{V}##, ##R_L = 180 k \Omega##, ##R_D = 18 k \Omega##, ##A_v = 5 \frac{V}{V}##. Homework EquationsThe Attempt at a Solution My question is about...

Certain aqueous ions have negative values for SO, such as Ca2+ with -55.2 J/(K*mol); how is this possible when dissolution is usually an increase in entropy? Also, all pure elements seem to have positive standard entropy value; why is this the case? Thank you.

I'm reading Padmanabhan's Gravitation. In section 3.4, at some point he writes the Lagrangian below: ## L=-\frac 1 2 \partial_\sigma V_\rho \partial^\sigma V^\rho-J_\rho V^\rho ## He then says that the sign of the kinetic term causes the time component of the V field to propagate as a wave with...

Homework Statement I'm just stuck on one part of a larger problem. I need to find the range of total angular momentum values for an electron in a j-j coupling scheme. Homework Equations j= l + and - 1/2 The Attempt at a Solution The electrons here are in a 5d 6s configuration. So for the...

Homework Statement Total Stopping distance = 50 meters Driver Reaction Time = 1 Seconds Coefficient of sliding friction = 0.58 Homework Equations D=(Total Distance)=V^2/2μg The Attempt at a Solution v≈36.66 (Initial Velocity) but I am sure what do after this step to find the negative...

<<Mentor note: Edited for readability.>> <<Follow-up: futher edited to fix LaTeX tags>> Context: FRW Metric /universe, perfect comological fluid , dark/vacuum energy So the equation of state ## w \rho=p, w=-1, \rho=-p## so this clealy implies either ##p## or ##\rho## is negative. Am I correct...

Homework Statement Homework EquationsThe Attempt at a Solution [/B] The electric field at the origin O, due to charges Q, q1 and q2, is equal to zero Hence , EQ = Eq1 q = cos30 x 300 x10^-9/4 * 1.8^2 = 210 x10^-9 C So I am able to find out that q = 210 x 10^-9 C and that mean that B and C...

I know that work is the "dot product" of force and displacement, but I got a little stuck with this problem: "Vera is driving her 1000-kg car at a speed of 8m/s. When Vera slams on the brakes, the ground exerts an 8000-N frictional force to bring the car to a stop. Determine the initial kinetic...

I have isolated a large molecular complex whose integrity is very sensitive to increasing ionic strength and thus had to be prepared for EM using low ionic strength solutions. And my goal is image this by electron tomography by collecting a dual tilt series of 120 images. Other experimental...

I read with interest the thread here https://www.physicsforums.com/threads/bells-theorem-and-negative-probabilities.59163/ and was trying to find out more about how a negative probability might be interpreted. I came across this and wondered if anyone could shed more light on it. "Let us...

New to the forum :) We were (trying to) discussing this at work the other day. Consider a simple battery powered circuit, with a resistor and an LED. With a battery, current is "chemically produced" in the battery and flows from the positive to the negative pole, passing through the LED...

Hi, Quick Qustion : If an object is propelled through the air (e.g. a ball is thrown), once the ball has left the throwers hand it will immediatly start to have negative acceleration (at least in the x plane). If the negative acceleration is measured at the same point in time after the ball...

This is not a homework question, but a question I am stuck on in my textbook. I have the answer but struggling to understand it. Homework Statement Picture below with answer. A positive and a negative charge of equal magnitude are placed at a distance 's' from each other on the x-axis as...

Hi Physics Forums! The ground state electron is the largest negative value, but what does this mean? Does this mean that kinetic energy is a positive value above zero? It seems at the ground state, the electron might also have kinetic energy as it is moving around as well as potential...

Hi, I'm planning on using a mosfet with my raspberry pi to controll a circuit, using the GPIO pins which can be set to +3.3V or GND but I'm having problems with choosing the type of MOSFET I will need. I've found the data sheet for a possibility here http://www.diodes.com/datasheets/ZVP3306A.pdf...

Homework Statement the focal point is said to be real and positive for concave mirrors and virtual and negative for convex spherical mirrors. what if the problem gives you the focal point for a spherical convex as 15 cm. am I supposed to take it that the the focal point should be plotted one...

Homework Statement In the case of the b trajectories, I want to understand why the electrochemical potential at voltage contact 3 must be the same as the current contact 4. And can you say anything about the electrochemical potential inside the sample itself? Homework Equations - I know...

Hello, My physics textbook describes negative work in cases where the force and displacement act in opposite directions. But I don't understand how work would be negative in the formula: W = F • d • cos Θ If the angle theta is 180 degrees, then the result of the cosine of 180 degrees would be...

Homework Statement If you were to throw a large log over the edge of the Grand Canyon and it took 5.65 seconds to hit the ground, calculate the velocity of the log at impact in m/s and calculate the distance the log fell in feet.[/B]Homework Equations vf=vi+at[/B]The Attempt at a Solution So...