Law Definition and 999 Threads

Homework Statement Two circular plates, as indicated in the figure, slide one over the other. Calculate the torque lost in this situation. The rotation w of the internal radius of the plates R1, the outer radius of the plates R2, the absolute viscosity of the lubricant between the plates (η)...

Dan put n different kinds of cheese in a row randomly, so that between two kinds of cheese there is a space. Then he puts a pickle on one of the n-1 spaces between the cheeses randomly. What is the probability of goat cheese and parmesan cheese (2 from n kinds of cheese) to be in the different...

if I get proof of fundamental laws like Newton's laws of motion or fundamental laws of thermodynamics then will they be laws anymore or will they become theorem. Please tell

What are indications for future development of transistors and general computing technology design with the Moore's law in mind? Are we going to redesign architecture for better efficiency and what future brings?

When we talk about current and ohm’s law, do we pretend that current is continuous rather than discrete in the same way that we do with charge distributions?

Hello, I have four questions. As it stands now, I don't have the necessary materials to test this myself, which is how I'd prefer to learn the answer. I still plan on doing this experiment for fun once I can acquire the necessary components. This deals with Lenz's Law. My goal is to maximize...

MODERATOR'S NOTE: NO TEMPLATE BECAUSE THREAD WAS ORIGINALLY POSTED IN A NON-HOMEWORK FORUM A monoatomic gas is present i n cylinder if its volume increase from 100cm3 to 200cm3 at constant pressure 1*10^5 what is change in internal energy. I tried to solve it but couldn't. I tried to solve it...

Is I understand it Hubble's law states that V = Hd = dx/dt Solving this differential equation, I got d = kexp(HT) where k is an arbitrary constant. This implies d²x/dt² = Hv = H²d and dⁿx/dtⁿ = Hⁿd. However (at least for me), finding the value of k is a problem, for 1, it must vary from galaxy...

With FIXED SOURCE AND RECEIVER, I have a light incident from fluid 1 with velocity v1 into fluid 2 with velocity v2. Obviously, according to Snell's law, v1/v2=sin(alpha1)/sin(alpha2), where alpha1 and alpha2 are the angles with regard to the vertical line. My question is: how to calculate...

Homework Statement A portion of a long, cylindrical coaxial cable is shown in the accompanying figure. A current I flows down the center conductor, and this current is returned in the outer conductor. Determine the magnetic field in the regions (a) R ≤ r1, (b) r2 ≥ R ≥ r1, (c) r3 ≥ R ≥ r2, and...

Homework Statement The accompanying figure shows a current loop consisting of two concentric circular arcs and two perpendicular radial lines. Determine the magnetic field at point P. Homework Equations B = μ/(4π) ∫ (I*dl x r)/r2 Btot = Ba - Bb The Attempt at a Solution For part a: Ba =...

Homework Statement The correct answer is 20.3 kg, but I got 23.4 kg. What did I do wrong here? Please refer to part 3 for the problem question. Homework Equations Refer to part 3. The Attempt at a Solution [/B]

If we have two frames related by ##x' = Rx## where ##R## is a rotation matrix and ##t'=t## Newton's law doesn't remain the same, for $$m \frac{d^2 x'}{dt'^2} = m \frac{d^2 Rx}{dt^2} = mRa$$ whereas it will be just ##ma## in the other frame. How do we solve this?

Homework Statement A metal rod can slide on a rail without any friction in the presence of uniform magnetic field of B=1T which is perpendicular to the plane of the paper.The distance between the tracks is d=0.1m and the resistance given is R=0.1 ohm.The resistance of the rail is negligible and...

Homework Statement I really don't know if I'm in the right subforum... I've started reading this text on statistical mechanics from MIT, but I'm stuck on page 2. Here's the statement: Let the equilibrium state of systems A, B, and C be described by the coordinates {A1, A2,· · ·}, {B1, B2,·...

Homework Statement For a lab, we explored Kirchhoff's Laws. I made a procedural mistake while measuring my voltage values across my different elements. I know that all of my calculated voltage sums are correct, so I was wondering what I might have done to have loops ACBA and CDBC have almost...

If we had a parallel circuit with a voltage of V between the beginning and end, and the circuit has a resistance R, then the current given by ohms law is I = V/R. What does this mean? The current is not the same throughout the whole circuit. Where is the current equal to this value?

Is correct to calculate the resistance of a semiconductor sample in a magnetic field with ohm’s law?

Homework Statement Two long wires, one of which has a semicircular bend of radius R, are positioned as shown in the accompanying figure. If both wires carry a current I, how far apart must their parallel sections be so that the net magnetic field at P is zero? Does the current in the straight...

1. Homework Statement i did part a,b,c but i am confused about part d.. i have a test tomorrow and will reattempt this when i wake up but i really need a hint here..so when the worker pulls upward he is decreasing the magnitude of -mg right? so if Fn and mg initially cancel each other out...

Homework Statement A ray of light is traveling in a glass cube that is totally immersed in water. You find that if the ray is incident on the glass-water interface at an angle to the normal greater than 48.7°, no light is refracted into the water. Calculate the refractive index of the glass...

Hi, The article below states that they made a material that blocks the motion of molecules in only one way but passing the other way is possible. See the article. https://physicsworld.com/a/blocking-the-symmetry-of-motion/ This seems to me in contrast with the second law. You can for example...

In the derivation of the electric field inside a non conducting sphere, We still use the permittivity of free space even though we are in a medium. The same applies for ampere's law in a solid wire. http://physics.bu.edu/~duffy/semester2/c15_inside.html...

Homework Statement A current I flows along a wire toward a point charge, causing the charge to increase with time. Consider a spherical surface S centred at the charge, with a tiny hole where the wire is – see figure below. The circumference C of this hole is the boundary of the surface S...

Homework Statement Hi, So I'm having some trouble deriving the biot savart Law. We have been given a derivation in the notes and I understand everything up until the last step which is labelled in the picture? Equating the two, How did the B vector turn into dB? It seems like he...

Hello, Can not Gauss's Law be used to calculate the electric field generated by a uniformly charged finite thread? I suppose it is because I can not consider the electric field constant (always going to the same direction), and for this I would have to do it by parts (the lateral flow, and the...

Homework Statement When considering a satellite in geosynchronous orbit, its speed is zero across (relative to) Earth's surface. From Kepler's third Law: T2=(4π2r3)/(GM), we can derive that v2=GM/r This would tell us that as the radius of a satellite to Earth's centre increases, its velocity...

Homework Statement I've recently watched a video which explains Kirchhoff's first law however, I'm not sure about his calculations. I got the same answer just wanting to make sure I am doing it right. the guy wrote L1: -75I2 +3V=0 ⇒ I2= -3/-75=0.04A He calculated L2 like -12V -125I3 +75I2=0 ⇒...

How is the centrifugal force in an orbiting planet or star, balanced if according to Einstein there is not such gravity force and is only space time curvature. Also, how come in order to determine internal pressure of a planet or star, the force acting near the center is calculated using the...

Homework Statement A person whose mass is 20 kg needs to accelerate vertically from the surface of the Earth at 5.0m/s^2 and is trying to pick which rocket he should strap to his back. How much thrust does he need if each rocket has a mass of 30 kg? Homework Equations F=ma The Attempt at a...

Homework Statement i'm viewing an example written in class. it looks like this: f(x1, x2, x3, x4) = [(not x1) * x2 * x4] ∨ [x2 * x3 * x4] what should be function after applying absorption law? Homework Equations i know how another option called "gluing" works: [x1 * x2 * x3] ∨ [(not x1) *...

Found this brief read on my new feed, thought it would be appreciated here.

The quotient limit laws says that the limit of a quotient is equal to the quotient of the limits. If we had a limit as x approaches 0 of 2x/x we can find the value of that limit to be 2 by canceling out the x’s. If we split it up we get the limit as x approaches 2 of 2x divided by the limit...

I’m a bit stuck with differentiating between the conservation of energy and D’Alambert. For a question I need to find the average resistance of the ground after it has been struck by an object. I chose to look at the equation as Ma + Mgh - Fr = 0. Can you advise if this is correct?

I'm confused by an apparent ambiguity in the direction the E field in Faraday's law: ∫ E°dl = - ∂/∂t ∫ B°da Faraday's law says the change in magnetic flux through an open surface gives rise to an emf equal to E°dl taken around the closed loop which is the boundary of the open surface. And...

What exactly does the electric field as solved for by Gauss’s law tell us? If you use a Gaussian surface that encloses no charge you find that the electric field is equal to 0. But if there is a charge outside of that Gaussian surface, it is not true that the electric field is 0 on the Gaussian...

Hello, I have seen that biot savart's law works for infinitely narrow wires: "The formulations given above work well when the current can be approximated as running through an infinitely-narrow wire." When I wanted to derive the magnetic field of a solenoid, I had to do this substitution...

Homework Statement Examine the charge distribution shown. b) What is the net electric field acting on charge 1? Homework Equations I used the equation E= (kq1/r^2) + (kq2/r^2) The Attempt at a Solution I subbed 9.0 x 10^9 in for k, 3.0 x 10^-5 for both q1 and q2, and 2m for r. My final answer...

Homework Statement Homework Equations The Attempt at a Solution E4Πr2 = Q/∈0 49000⋅4Π4.12 =Q/∈0 Q = 91.6 μC Qshell = Q = 91.6 μC Qshell = Qinner + Qouter 91.6 = -3.3 + Qouter Qouter = 94.9 μC Can someone point out the error? I have skipped too many lectures and I am catching up right...

I am having a doubt of why is the radiative flux IvdvcosΘdw in equilibrium integrated for a spherical black body only from 0 to pi/2 not pi(e.g. For the entire surface for which it is zero), v=frequency dw= solid angle

If the universe keeps expanding and eventually ends in a "big freeze" or heat death, does this contradict the third law of thermodynamics? The third law of thermodynamics states that a crystal at absolute zero has zero entropy. Since the entropy of the universe can never decrease, as the age...

Are the laws of conservation of mass always obeyed. in a nuclear reaction mass is converted to energy therefore mass isn't conserved. I understand that energy is always conserved, but I feel like mass isn't.

Homework Statement Kepler's Constant for any object or planet orbiting the sun is 3.36x1018m3/s2. Calculate how long a year is for Pluto given the "radius of object" is 3.0x106m and the "mean radius of orbit" is 5.9x1012 Answer: 7.82x109s Homework Equations K = T2/R3 The Attempt at a...

Homework Statement We put a pole with a length of 0.2m in a magnetic field equals to 0.4T and move it with a velocity of 4m/s. What is the value of the charges that accumulate in the ends of the pole? Homework Equations E=Bv ε=El The Attempt at a Solution I know that E=1.6V/M and ε=0.32V (Book...

Homework Statement Homework Equations is biot-savarat law and ampheres law equivalent? The Attempt at a Solution

Homework Statement Find the speed at which a car of mass M will lose contact with the frictionless road Homework Equations Centripetal/Centrifugal forces (maybe?) The Attempt at a Solution I used OneNote to attempt this problem[/B]...

Hi there. I am trying to derive Gauss's law from the divergence. I would like to know if it is correct: The divergence is defined as (I saw this on Fuller & Byron "Mathematics of classical and quantum physics") ##...

Homework Statement https://gyazo.com/f8cf156e7bd2f2511e3fa859e3732fe6 Homework Equations Snell's law. The Attempt at a Solution I'm mostly confused about the relevance of the second medium (of index n2) given that the distance between the ring and the boundary is "small". Having attempted to...

Homework Statement Homework Equations Stokes Theorem The Attempt at a Solution I'm having a tough time "cancelling" out integrals from both sides of an equation (if possible). On the right hand of the equation, we know since it is a closed curve, that Stoke's Theorem applies and we can...

Homework Statement Three separate spheres next to each other. The one on the left is positive (charge of +25.5μ C). The one on the right is negative(-25.5μ C). The two are separated by 0.25m. The third sphere has a charge of +2.5μ C and is placed exactly halfway between the two. Find the force...