Concept Definition and 1000 Threads

Homework Statement A gas contained in a piston-cylinder assembly undergoes two processes, A and B, between the same end states, 1 and 2. State 1: P1 = 1 bar, V1 = 1 m3, U1 = 400 kJ State 2: P2 = 10 bar, V1 = 0.1 m3, U1 = 450 kJ Process A: Constant-volume process from state 1 to a pressure of 10...

Hi, please help me with the following questions ! can we say that harmonics are because of Reactive Power (i know that one way of controlling harmonics is filtering) ? IF YES, can we control Reactive power by increasing Power Factor ? IF YES it means Harmonics can be controlled by increasing...

Homework Statement A truck is pulling a car. is the magnitude of the force that the truck exerts on the car is the magnitude of the force that the car exerts on the truck Consider the following scenarios independently. 1. The truck is driving up a mountain with a constant velocity...

Hi I'm just having trouble wrapping my head around differential equations with matrices and vectors... For example: let y be a vector. let A(t) be an nxn matrix. I have the differential equation: dy/dt = A(t)y So I think I understand why the solution is y = ceA(t) But I'm having trouble...

Let's start with a vacuum, I will write |0000...> as |0>. $$ \psi^+ (x) |0\rangle = \sum_k e^{-ikx} a^+ (k) |0\rangle $$ Qns: What happens if you superpose/add up state vectors corresponding to a particle of momentum k and you add up with coefficient e-ikx? $$ \sum_k e^{-ikx} a^+ (k) |0\rangle...

In the past, reciprocating engine platforms have prevented the use of thermal insulating materials like ceramics due to, among other reasons, abrasion and vibration. One of the problems in the past has been the movement of the piston and piston rings over the cylinder wall where the insulating...

I am in introductory physics, and have just been introduced to the topic of toque. For forces in translational motion, I know that we idealize objects to be point particles. However, when it comes to torque, we don't deal with point particles, but with "lever arms." I guess essentially my...

Homework Statement What is the formula of a compound containing 3 moles of oxygen, one mole of aluminum and 3 moles of hydrogen in each mole of the compound? Homework EquationsThe Attempt at a Solution I don't really understand the question at all.

Homework Statement Using a galvanometer and a coil, we thrust a magnet with a defined north and south pole into the coil and the galvanometer measured the induced current created. Now, depending on how the coil flow(front to back or vice versa) the galvanometer measured an induced current...

Homework Statement Homework EquationsThe Attempt at a Solution 1) charges should remain the same since there is no path for them to go anyway. 2) Now, if the panels were of infinite length, I believe the electric field should be the same regardless of distance? But in this case, the panels...

Homework Statement Hi,I am learning to solve 2nd-order differential eq. Suppose I have a equation dy/dx - 3x = 0...(1) Then dy/dx = 3x -----> x = 3(x^2)/2 Now if I have a 2nd order ODE such that: d^2y/dx^2 = 3....(2) Then it could be solved by integrating both sides wrt x twice,which yields y...

Homework Statement Is the statement cirrect: "the rate at which a wave transfers energy depends on the amplitude at which the particles of the medium are vibrating." And does the energy=A^2 ? Homework Equations E (proportional) A^2 The Attempt at a Solution For the statement I am about...

I am trying to understand the concept of interatomic spacing. Below is a link to three pictures, and my questions is: why are they different? I thought atoms were packed together touching each other like in the first picture but the second and third imply otherwise. Any explanation or help is...

I have a problem with static/non-static spacetime. The problem is that the notion of spacetime includes time itself, so how can it change with time? Imagine an asteroid approaching the Earth-Moon system. The Earth-Moon system is a non-static spacetime, so presumably is giving off gravitational...

ca·tab·o·lism The breakdown of complex molecules, in living organisms, to form simpler ones, together with the release of energy; destructive metabolism. I don't understand this part of the definition together with the release of energy So anything anti catabolic would be a non breakdown of...

Hi This is my first post and I have come here as I cannot find an answer anywhere else. So, my physics knowledge is limited to what I learned in High School, supplemented with the odd bit of further reading via books and the internet. However, many of the concepts I learned about I find...

[Note from mentor: This was originally posted in a non-homework forum so it doesn't have the homework template.] ----------------------------------------- Problem: The surface of a solid metal sphere (radius r = 4.58 cm) is at potential V = 9,851 Volts. Find the magnitude of the potential...

Then why did they find out it's harder to accelerate particles when they are near the speed of light? Even the lorentz equation indicates that the dimension is mass (rest mass / lorentz factor). Infinite energy is required to accelerate an object approaching to the speed of light, but what did...

micromass submitted a new PF Insights post The History and Concept of the Number 0 Continue reading the Original PF Insights Post.

1. Momentum is not a force nor energy, it is a completely independent thing 2. Both p = mv and F= ma is for calculating the effort of changing the speed of an moving object, but the former one do this through comparing the momentum of an object before and after it changes speed while the latter...

Hi, I'm reading a high school textbook about mechanics. It's amazing how the author draws up the problems and solves them by introducing a new consistent concept. Now I'm reading about collisions. He writes the conservation of momentum but the problem is that we have two unknowns in one...

Hey guys!, this is my final year aeronautical engineering project that me and my group are going to work on! we have this concept of producing a roll in an uav/RC aircraft by reducing the area of the wing on one side while keeping the other side area constant or increasing it(gradually) and...

int_0^(pi) sin(t)/[3 + cos(t)] dt Answer: u = cos(t); du = -sin(t) dt; a = 1; b = -1 int_1^(-1) -1/(u + 3) du int_(-1)^1 1/(u + 3) du = ln(u + 3) from F(1) - F(-1) ln(4) - ln(2) = ln(2) I had help on this. And there are a few aspects I don't understand. What is the purpose of a=1; b=-1...

Homework Statement A small solid sphere of mass M0, of radius R0, and of uniform density ρ0 is placed in a large bowl containing water. It floats and the level of the water in the dish is L. Given the information below, determine the possible effects on the water level L, (R-Rises, F-Falls...

When we are given a problem to find the value of say tan(120 °), I was instructed to proceed by tan( 90*1 +30), which lies in the second quadrant and tan is negative in the second quadrant , plus odd multiple of 90 so it becomes -cot(30). Hence tan (90+α)= -cotα. But this works only because we...

Hi, I was using Hasse Diagram as it is great tool for data analysis but there is a confusion the thing is that I downloaded a software for fca and every time it uses a algorithm it gives a different lattice ,I do understand but suppose I am using it for some representation of concept lattice...

Homework Statement If an electron in metallic cesium absorbs a photon of red light (6.6x10^-7) m in vacuum), all the energy is used up in escaping from the attractive forces in the metal. Suppose light with 5x10^-7 is used, what percentage of the photon's energy does the electron retain after...

Homework Statement [C2O4]-2 ------> CO2 Find if the reaction is oxidation or reduction and determine the no. of electrons lost or gained by carbon. Homework EquationsThe Attempt at a Solution I started with finding the oxidation states of both elements. It's 3+ and 2- for carbon and...

I'm unsure if the following is true or not in the absence of external forces: Electric potential is a scalar quantity. This I know is true because there is no direction associated with potential energy. It is always possible to assign a value of zero to the electric potential at the...

Hi, I shall be grateful if someone can help with this fundamental understanding, Thermal resistance (in case of conduction mode of heat tarnsfer) can be defined as; Rt = L / kA where k is the thermal conductivity Thus. thermal resistance if inversely proportional to the thermal...

Homework Statement [FONT=Arial]A cyclist with a bell ringing with a frequency of 658.8 Hz drives towards a wall with a speed of 3.18 ms-1. Just before colliding with the wall the cyclist hears beats, due to the bell itself and the reflection of the sound from the wall. What is the frequency of...

I was reading a fiction book and they mentioned a fascinating concept described as "spiral time" - are there any credible scientific hypothesis concerning such as thing - no matter how generally outlined? The concept, obviously is that time is neither a unidirectional timeline nor a circular one...

The most so called "difficult" topic in chemistry mole.I am Confused in it a lot..please clear the doubt. Firstly,The mass no of each elements means the mass Of how much atoms in the elements and relative to what.as we know we assume a prototype as scientist did named it as kilogram and then on...

Homework Statement A particle moving along a straight line can have nonzero acceleration even when its speed is zero (for instance, a ball in free fall at the top of its path). Can a particle moving in a circle have nonzero centripetal acceleration when its speed is zero? If so, give an...

1. So my teacher gave us examples of how to solve capacitor problems. I know how to solve the problem but I don't this problem's particular "formation" of parallel capacitors. In this problem, my teacher says C3 and C4 are parallel but when I did the problem, I assumed it was series. Can anyone...

I always have some interesting on the photon. after I read the oscillator expansion of the electromagnetic field in a finite volume, I find photon is more a mathematical concept in theoretical physics than real particle. not like electrons, number of photon is a representation of the energy...

The kinetic energy of a photoelectron is independent of the intensity of the light. If we increase the intensity of the light, the effect is, the number of photons arriving will increase and in turn we will eject more photoelectrons. However, the maximum kinetic energy of anyone photoelectron...

What is the exact definition of force leading to F=ma? Couldn't we define another equation for force, say F=mj or maybe F=2ma? I think it is because of our senses and the force is defined by the Hooke's Law F=kx, but I am not sure..

Is it necessary to pass magnet through solenoid in Faraday's law experiment. If not, then how much emf could be induced if a normal bar magnet crosses a copper wire solenoid from a distance of approx 1 meter.

Homework Statement Consider an electron-proton pair and compare its electrostatic force with that of the gravitational force [G=6.67x10^11 Nm^2/kg^2]. Homework Equations F = k * |q1 * q2| / r^2 k = 1/4π∈ The Attempt at a Solution I calculated the force by using the charge of an electron...

Homework Statement I am trying to work the moment of inertia for a) rotating rod, axis through the centre of the rod http://hyperphysics.phy-astr.gsu.edu/hbase/mi2.html#irod3 b) Solid cylinder http://hyperphysics.phy-astr.gsu.edu/hbase/icyl.html#icyl2 [/B] Homework Equations I = R^2 dM The...

"Why do so many physicists believe there has to be a structure to the vast voids in space" ? Surely, Their thinking defies the basic principles of physics, i.e. in order to have something there has to be nothing ! to have a positive there also has to be a negative, so as for the positive to...

Hi, so I've just started learning about physics and I get the gist of most of it. I understand motion, torque, energy, light, radioactivity. But there is one topic that absolutely stumps me. Electricity. Can someone explain to an absolute moron like me what it is? It seems like everyone around...

I was watching a video on youtube with a theory of time, the video explains 'Time' as a physical process supported by mathematics) I want to know what you think about this? Pseudoscience, or have any validity? "Could the future be an emergent interactive property with 'time' formed by the...

How can it be proved that as lim n tends to infinity, (n2-1)/(n2 + n + 1) tends to 1 ?

Homework Statement A frog sits on the end of a long board of length L=5m . The board rests on a frictionless horizontal table. The frog wants to jump to the opposite end of the board . What is the minimum take-off speed (in s.i. Units) i.e.,relative to ground 'v' that allows the frog to do the...

Hello I do not fully grasp the concept of Riemann geometry.Please can you use mathematical descriptions but explain them because I am only a 10 year old but of course I know significantly the theories of dimensions. Thank you.

According to the concept: when a planet revolves around a star, and when both the bodies move in circular orbits due to the interaction between each other, both the bodies can be replaced by a single body of mass ##\mu## revolving in a circular orbit of radius equal to the distance between both...

So I'm trying to figure out the electric field that is acting on a point. This point is .3 m right of a point charge with -2N/C and .8m from a point charge with +4N/C. I've drawn it out, and realize both will have an impact on this object. what the issue I'm having is figuring out a formula to...

1. We have two positive point charges (+q) at a distance from each other 2. Goal is to Find electric field at point A halfway between the point charges 3.By logic and summation of fields we should get ZERO 4. But how would I use a gaussian surface (sphere i assume ) to prove at point A...