Law Definition and 999 Threads

[Moved to homework, so no template] Summary:: trying to figure out physics for current and having issues. keep getting something that does not make sense. working on this issue, and i think i have to find ttl resistance, to find current using ohms law. looking at the circuit attached there is...

I am trying to get more confidence on the direction of current using Amperes law, the problem statement is Loop1: My first task was to assign the direction of current. If I wrap around the my right hand fingers in the direction of integration the thumb is pointing up hence Positive Y direction...

Hello, I'd like some clarification with the exact wording of Kirchhoff's law of thermal radiation. The law states that at thermal equilibrium αλ=ελ. However sometimes I read that absorptivity= emissivity and sometimes I read that rate of A. = rate of E. Which one is correct? I'm not sure but I...

I tried validating the equation by somehow 'solving' only with the involved units. Magnetic Flux Density – Tesla (T) – Weber (Wb) per square meter (Wb/m2)

This is the problem, first time i am attempting the Ampere's law problem From the above question this is my attempt, the picture is ∫B.ds = μ*Ienc; ----> Ampere law , where Ienc is the current enclosed in the amperian loop. I assume the circle as the amperian loop, is it correct? Can i...

No idea how to solve

Good afternoon, My question concerns Maxwell's first law. Knowing the formula of the electric field created by a uniformly charged disk, we calculate its divergence and evaluate it at one point, it does not give us zero, as it should be because the volumetric density of charge is zero, why does...

i have little experience with the differential form of Gauss's Law, and I've tried three times now to arrive at it for a point mass M (spherically symmetric classical gravitational field) but instead of getting an answer proportional to the mass density I keep getting zero. Is the divergence...

We have a closed chamber of 20 liters. The bottom of this chamber is filled with ammonia solution of 5% (=2,7M/liter). The solution temperature is controlled at 40°C I would like to calculate the concentration of ammmonia in the chamber air, above the solution. It should be something with...

Hello everyone I was hoping someone could shed some light on the following:- I am trying to derive the equation of Momentum from Newton's 2nd Law. What I know is the following:- I don't know how to get from Force = Mass * Acceleration TO Momentum = Mass * Velocity. I have attempted to...

Hi. My understanding was that a scientific theory and law complement each other. There is a guy at work that insists that a theory with more evidence becomes a law. Recently he cited an article that said that a theory that has been repeatedly verified and appears to have a wide applicability in...

Quoting from Modern Cosmology by Andrew Liddle on pages 130 and 131: "Let me stress right away that the luminosity distance is not the actual distance to the object, because in the real Universe the inverse square law does not hold. It is broken because the geometry of the Universe need not be...

Hello, As far as I know, the standard sign convention for Kirchhoff's law are: For resistor: the potential difference (voltage) is negative if the chosen loop direction is the same as chosen current direction through the resistor, positive otherwise. For battery: the voltage is positive if the...

Note that the solution is 5625 V/m in z direction which is found easier using Gauss' law, but I want to find the same result using Coulombs law for confirmation. Lets give the radius 0.04 the variable a = 0.04m. ##\rho## is the charge distribution distributed evenly on the surface of the...

I'd like to apply the 1st law of thermodynamics in a reference frame (RF) moving with constant velocity. We have: ##\Delta{}E = E_{in} - E_{out}## I am limiting myself to rectilinear motion. Suppose we are in a RF moving with a constant velocity ##V##. Let the system consist of a mass ##m##. The...

My question is going to be rather specific. I am trying to understand how Gauss's law applies to this scenario. I know if a cylindrical shell is infinitely long, and there is an external electric field, the inside of the shell will have an electric field of zero everywhere. I am wondering...

There are many diagrams like the following which demonstrate that if A acts as a point source of wavelets, then we will have constructive interference in the case that ##i=r## as shown, as we can show with a little geometry that the path difference is zero. However, surely this isn't the...

Hi, The shown below, Figure 1, is an interaction of magnetic fields of stator and rotor of a squirrel cage induction motor. I believe the current is coming out of the squirrel cage bar on the left and entering on the right as is shown below, Figure 2. I have assumed that the bars highlighted in...

When proving that Newton's Universal Law of Gravity will produce an elliptical orbit, the radial acceleration is confusing to me. Can someone please explain how the radial acceleration is equal to d^2/dt^2 - r(d x theta / dt)^2. Could someone please detail how that acceleration is derived...

Hello, and thank you again to anyone who can confirm if I have the right answer or who can give me some suggestions. This question felt like a bit of a surprise because we have not yet covered one where the mass of a planet was missing. Thus, my confidence in my work is low. Part b felt like a...

my question is in fig.

I know that the normal force and Fg are unbalanced in this case, but I don't get how to set up the equilibrium equations with that. I struggle with determining what you set the equations equal to when its either balanced or unbalanced forces you're dealing with.

Thank you very much your time! I first found the force of the air on the boat using the principle of Newton's third law and the fact that no friction is involved. Faction= -Freaction 150 N backwards = -150 N backwards 150 N backwards = 150 N forward I then sought to determine the...

My textbook tells me that one of Maxwell's equations, namely divergence of E = 4pi * charge density (in cgs) or divergence of E = pi / epsilon nought (in SI) is exactly equivalent to Coulomb's Law. How in the world is that so? Any ideas would be appreciated.

θ = 4 μs = 1 Fnet = Wpararell + fs m.a = 1/2.m.g.sinθ + μs.1/2.m.g.cosθ (divide by m) a = (g.sinθ+μs.g.cosθ)/2 a = ((9.8)sin4 + (1)(9.8)cos4)/2 a = 5.23 m/s^2 hello guys, I'm having trouble with this problem. Can anybody help me correct my attempt and explain it to me?? thanks

Hi everyone, I am currently trying to work something out in regards to non-equilibrium thermodynamics. If I have a block of metal in vacuum that is being heated by a laser with a constant power P, is it even possible to be able to describe the emission of radiation by the block via the Stefan...

I drew a free body diagram for the books but it's not the same one in the correction. The static force Fs between the books and the table must be opposite to the motion but the correction does not the same and puts that vector in the same direction as the motion. Here's a drawing of the...

Firstly, this is not a homework question. I found a worksheet online with an example of a square law circuit built using log-antilog operational amplifiers. I tried to derive the transfer function but I can't seem to eliminate the reverse saturation current term ##I_S##. I would really...

This is a question in my midterm. I calculated for the answer as c) 11.7 atm by the Ideal Gas Law. The professor states that "all the air is originally at 1 atm" in the prompt indicates an idea of "both 70 L of air and existing 6 L of air in the tank are at 1 atm", and he grades d) 12.7 atm as...

Assume that an individual only has two possible states: susceptible (S) and infected (I). Further, assume that the individuals in the population are independent, and that for each susceptible individual the time until the next infection follows an exponential distribution with expected value 1/λ...

I have read multiple threads on Physics Forums, Stackexchange and Quora, as well as the explanation of Gauss Law, but still don't understand the most fundamental aspect of it: its applicability for any kind of surface. More precisely, I don't get how this follows from the fact that...

Hi, I will use this text for my question: https://imagizer.imageshack.com/img921/1874/nUBPY6.jpg Source: https://www.electrical4u.com/lenz-law-of-electromagnetic-induction/ The text says that when the north pole of a magnet approaches the coil, the induced current in coil is such that it...

Hey everyone! I have been looking everywhere to try to find the answer to this question so I thought I'd pose it here. When we discuss finding the mass of orbiting bodies, it's easy to find the combined mass of the system using Kepler's Third Law in the form M1+M2=(4pi^2)(a^3)/((G)(T^2). My...

Hi gentlemen. My model is simple. Imagine, I watch a body which approaches me with velocity of w which value I can measure . I know that this a body has velocity v in a some reference system which aproaches me with same velocity of v. This velocity needs to be calculated (I can not mesure it)...

I've just been learning about Gauss' law which as far as I can tell states that the net electric flux through a surface equals the enclosed charge divided by the permittivity of free space, and is often expressed as the integral $$\int_S {\bf{E} \cdot d \bf{A}} = \frac{Q}{\epsilon_0}$$In some...

Hello all I am trying to understanding Newton's 2md Law of Motion which states:- Force = Mass * Acceleration If I had a force of 10Newtons pushing an object along the ground (assume no friction) in a perfectly horizontal direction that has a Mass of 10kg then the objects acceleration would be...

The formulas we have been given include Potential energy=mgh, Stored strain energy=(1/2)K(change in X)^2, , Kinetic energy=(1/2)mV^2, Work=F(change in d), Force=K(change in X). Not sure how exactly to answer the question.

Hi everyone! I have started to study physics this month and I got to the Newton's laws. According to Wikipedia, the first law is: This definition made me wonder: If there was, let's say, a fictional road, infinite long and frictionless, and a body would move in constant velocity over it, could...

Answer choices: N2L for Translation, N2L for Rotation, Both, Either1. You are asked to find the angular acceleration of a low-friction pulley with a given force exerted on it. My solution = N2L for rotation 2. You are asked to find the angular acceleration of a low-friction pulley due to a...

I've attached an illustration of my set up.

I am curious about the historic experimental evidence that lead to Kirchhoff's radiation law. It is easy to take for granted the ubiquitous temperature/wavelength curve that lead Planck to the quantization concept. But I wondered historically how the curve was derived. To clarify, we...

This question will sound mostly stupid but anyways. We see that galaxies have some velocity due to the Hubble law. Let's take an object that has a recessional velocity of ##v##. In SR case assuming the universe is nearly flat, can we say that the galaxy gains mass relative to us ? I guess in...

I am having troubles with a question I have to do for my chem pre-lab. The question is: The following intercept and slope were obtained for a Beer’s Law plot of Absorbance versus concentration (mg Fe2+/L). Slope = 0.2200 L/mg Fe2+ Intercept = 0.004 Calculate the percent (by mass) of iron in the...

In one of my textbooks about quantum mechanics, they mention a vehicle moving in a straight line along the x axis. With Newtons first law they take the second derivative from a which is d^2x/dt^2 and that should be equal to -∂V/∂x. What exactly does -∂V indicate? The complete equation...

As I mentioned I am self tutoring myself on a subject I studied 20 years ago. I'm sure I can answer all the questions apart from question (iii). I think I'm supposed to use a simultaneous equation. But I need to answer question (iii) to answer the rest. Any help please?

m1 is the large cruise ship m2 is the tug boat The question doesn't state it explicitly, but I assume that both masses are undergoing acceleration because the tug boat is experiencing a change in velocity. I assume the system accelerates uniformly, and I assume that m1 and m2 accelerate...

I tried to think why Ampere's law seems to fail in this case. For me it was clear that there is no symmetry in the z direction, there is no translational symmetry because of the finiteness of the wire. On the other hand, I know that Ampere's law is independent of the loop we take. This also...

P1= 13.6 V1= 1.1 T1= 22 P2 = 14.4 V2= x T2 = 32 my answer is 1.51L am i missing something?　

How does viscous force depends upon velocity gradient?