Energy transfer Definition and 150 Threads

There's been some buzz about wireless energy transfer for quite some time now, but it seems really far fetched to me that we will get any significant power usage out of wireless energy transfer. What do you guys think? Does this form of energy have any significant potential at all, or is it just...

Hi forum I need to explain the following to pupils of about 17 years of age. 2 questions regarding free electron kinetic energy transfer to copper wire (or resistor) material atoms in an electrical circuit. 1. I am confused as in which situation free electrons in a circuit transfer...

Compound A has an albedo value (visible spectrum) of 0.08, and an emissivity (infrared) of 0.08. Compound B has an albedo value of 0.04 and an emissivity of 0.88, in the same spectrums. We need to explain why A is more effective at transferring energy to the water flowing behind it, when...

Homework Statement A silver block, initially at 58.5* C is submerged into 100.0 g of water at 24.8* C, in an insulated container. The final temperature of the mixture upon reaching thermal equilibrium is 26.2* C. What is the mass of the silver block? Homework Equations q = M x Cs x Δ T 1/M...

When I walk do I transfer energy to the ground via my foot, if so would the ground/earth than gain an extremely small amount of mass because e=mc2

If Newtons third law says there is an equal and opposite reaction how can there be energy transfer. For example if I push a box and give it 1000 joules of energy wouldn't it "give back" the energy. Also does an object have to be moved for it to gain energy, if I were to punch a book many times...

Task: A steady flow boiler takes in feed water at 1.5kg/s, at a temperature of 30 °C. The water is heated and turned into wet steam. This leaves at 1.5kg/s, with a pressure of 10 bar and a dryness fraction of 0.97 to the superheater, where it receives heat at a constant pressure and emerges...

I wasn't sure whether this question belonged in relativity or QM, or even just plain classic. This forum seemed the best bet, but I am not using speeds near C - mere Galilean relativity will suffice here. I have two objects, A and B A is moving with velocity V and thus has kinetic energy E...

Homework Statement A system consists of two masses. The system has normal modes of frequency wa and wb. Suppose one of the masses is displaced. How long will it take for energy to be transferred to the other mass and then back to the first mass. this question is a review question for my...

I have an exercise with the following text: Suppose you put both electrons in a helium atom into the n=2 state. What would the energy of the emitted electron be? I have attached the solution to the problem, but I am not sure I understand it. I understand the first part about the total...

Homework Statement A closed system consisting of 14.5 lb of air undergoes a polytropic process from p1 = 80 lbf/in2, v1 = 4 ft3/lb to a final state where p2= 20 lbf/in2, v2 = 11 ft3/lb. Determine the amount of energy transfer by work, in Btu, for the process Homework Equations W = ∫v1v2p...

Why does no temperature change occur while ice is melting? Specifially, when very little ice is left, how does so much water remain at 0 degrees Celcius? Is the energy transfer (of heat) to ice constant? Specifically, does the time range in an exponential manner for different sizes of ice to...

Consider a magnet moving towards a coil. We know that the motion of the magnet will induce a current in the coil and the direction of this induced current is to oppose the motion of the magnet. Now does the magnet experience resistance to its motion immediately as soon as it starts...

I've been trying to understand what happens on a microscopic level - in terms of charges and EM fields - in a simple circuit (say a battery with wires to a lightbulb), and I'm finding it pretty difficult. I read these articles that try to untangle the flow of charge from the flow of energy, and...

Let's consider a mach-zehnder apparatus The picture is below: http://en.wikipedia.org/wiki/File:Mach-zender-interferometer.png 1. When the photon encounters (and emerges from) a half-silvered mirror does it loose any energy? The photon does change phase when it moves through a half...

Understanding energy transfer during the creation of entanglement Below is an attempt to understand the energy transfer process during entanglement, please correct where required. Broadly/conceptually speaking: There are two kinds of 'energies’ associated with a photon. 1. The photon...

When I have a full tank of compressed air that I need to move to another tank will it require the same amount of energy that it took to compress it to move it? 2 -- 318 cubic feet (equal volume) compressed air tanks are side by side. One is full at 312 psi and the other is at atmospheric...

First: Theoretically, is it possible to transfer all of an object's KE to another object? e.g. (ignoring gravity, friction, sound, etc.) an object with mass=M and 1eV collides with another object of mass=m and 0eV-- afterwords, object M has 0eV and object m has 1eV (conservation of...

Hi I am thinking of ways how to transfer electricity so that I can separate the phase magnetically or otherwise, Ok we all know transformer is one way to do it but it's big with mains frequency, other would be pulsed DC in an smps , but that's is already a very tried idea, is there any other way...

I have two fishing lines that are of the same material but one has a larger cross sectional area than the other, which one will transfer energy faster? I am not a physics person so a simple amswer would be appreciated. Thanks

Homework Statement Propose an explanation for the following fact. Include a description of the energy transfers that would take place when the lift starts and stops. A fully loaded chairlift requires more energy to start then it does to maintain motion. The Attempt at a Solution I...

Hi everyone! How do these two types of energy work for things that are being lowered down slowly? I've been told that whenever one drops something (let's say it's 1kg) from 5 meters, it will be traveling at 10 meters per second just before it stops at the ground. And I've also learned that...

Hallo, I want to calculate energy transfer from an electromagnet that consumes 12W of electricity that's about 12J/S of energy transferred to: A. a non-magnetic rotor shaft( Do I have to include the magnetic field information?) B. permanent magnet rotor shaft * Electric energy > Mechanical...

Hello, I have a problem with the two seemingly conflicting descriptions of the energy transfer from a photon to an electron I found in my textbook. The first one appears in the description of the photoelectric effect: "In Einstein's picture, an individual photon arriving at the surface...

I'm working on setting up an experiment to test, calculate and compare the "stopping power" of various defensive handgun loads. This experiment assumes that "stopping power" is some sort of calculation like "power"/penetration distance, meaning that the higher the "power" and shorter the...

Ok, so want to clarify something: A nuetrino can change between flavors as it moves through space. A nuetrino that starts out as an electron nuetrino can turn into a tau nuetrino or a lepton nuetrino, or mixtures of the two. It can then turn back into its original electron nuetrino...

Let's say I have some simple molecule excited to higher electronic level. Is it possible that it goes back to its ground state by transferring the excitation energy into its vibrational degrees of freedom? I believe it is... what are the selection rules for such a process? TIA

A quartz tube contains one mom of gAs at 20 deg c. The gas is heated at constant volume to 300 deg c. How much thermal energy is transferred to the gas? If the same amount were heated at constant pressure, how muh energy would be required? I know how to solve this for constant volume using E=...

Hi all, I've a hamiltonian that describes the coupling of electrons in a crystal (bloch electrons) to an EM field described by a vector potential A \begin{equation} \mathscr{H} = \frac{e}{mc}\left[\mathbf{p}(-\mathbf{k}) \cdot \mathbf{A}(\mathbf{k}, \omega)\right] \end{equation}...

So, what I'm wondering is if it is possible for a kinetic energy transfer between 3 objects. Much like a pair of billiard balls, I would like to know if one can have two mobile objects collide with a still object at precisely the same time. Having all of the kinetic energy in both moving...

Homework Statement During a food lesson, some students wonder why the metal spoon inside the saucepan gets hot but the wooden handle does not. Explain how the energy is transferred from the cooker to the end of the metal spoon (and why the wood doesn't get hot). There is water in the...

Homework Statement Twenty grams of silver and gold (total mass of the gold plus the silver is 20 grams) is used to convert 1 g of ice at -3°C to steam at 100°C. If both the silver and the gold are at their melting points at the beginning and the final temperature of the silver, gold and steam...

I'm reading about this now. Apparently dividing the expression for the kinetic energy that a slice of air possesses at a point in time by time gives you the rate of energy transfer of the wave. This makes no sense to me.

When an accelerated charged particle is shot into an electromagnetic field such that the accelerated particle comes to a complete stop in the field, we naturally have loss of energy from the charged particle. But what is this energy converted to? And where? Does the particle release radiation...

Homework Statement 1) 27,000 kg railroad car moving at 2.7 m/s hits a railroad car (stationary) weighing 9,300 kg. Heavy railroad car goes opposite direction at .6 m/s. How fast will the empty car go? Homework Equations no clue The Attempt at a Solution No idea where to start...

Peter M McGinnis describes work as being 'the means by which energy is transferred form one object or system to another' in Biomechanics of Sport and Exercise. Many people explain that deformation of a car striking a solid object or a body striking the ground as the object or ground doing...

I have some doubts concerning work, here are some examples I wanted to clear out: So, when I kick a football, I am doing work on it. In this example the ball will be in contact with the ground throughout. It will slide over the floor. The Energy Transfer: Chemical Energy from my muscles to...

Hi, I was wondering, for a process that produces a large amount of heat, are there any efficient systems out there to transform this into different types of energy (chemical potential, electrical, mechanical, etc) with a high efficiency (80-90%+) Thanks.

Hi guys wonder if you could help me out with a little project I am working on building.. Basically its a device that fires a .22 blank and I am struggling with consistency of shot so I have two alternatives for the hammer action. First one A has the firing pin attached second one hits the...

Hello, The statement in question is: "In Newtonian mechanics, changes in the energy state of a point particle are described by the equation dK + dU = dE, whose terms are the (infinitesimal) changes in kinetic, potential, and total energy, respectively. The total energy change dE describes...

can someone confirm that the equation for the linear energy transfer is: LET=-\frac{4\pi e^4Nz^2Z}{m_0v^2} (ln\frac{2m_0v^2}{I}-ln(1-\beta^2)-\beta^2)=-\frac{dE}{dx}, where e is the charge of an electron, Z is the atomic number of the material being irradiated, m_0 is the mass, z is the...

Hope you can help my understanding. Looking at entropy from a stat mech standpoint, two systems brought together will result in a higher entropy system. According to Kittel, the most probable configurations will dominate the statisical properties of the combined system, most probable...

I am currently stuck on how to work out this question. Calculate the energy transfer in 1200s in a component when the p.d across it is 12V and the current is 2A. I have been attempting it for at least half hour but still no luck. Can somebody please help me out on how to work it out :)

Homework Statement ice has formed on a pond and steady state has been reached. the air temperature above the ice is -10 degrees celcius, while at the bottom of the pond the temperature is 4 degrees celcius. the total depth of the ice and water is 0.50m. if the thermal conductivites of ice and...

Hi, When 2 bodies are close together such that their evanescent fields are interacting, what sort of energy transfer can I expect to take place between the bodies ? That is, how can I expect the energy transfer to vary with gap (i.e exponential variation? some sort of a power law? )...

Homework Statement A 613.0 kg mass is placed on a forklift that can generate 950 W of power. What is the constant speed of the forklift while lifting this load? Homework Equations P= E/T e=energy in joules T= time The Attempt at a Solution not enough information therefore i...

Homework Statement A glass windowpane in a home is 0.62 cm thick and has dimensions of 1.0 m x 2.0 m. On a certain day, the indoor temperature is 25˚C and the outdoor temperature is 0˚C. a) What is the rate at which energy is transferred by heat through the glass? b) How much energy is lost...

Help Asap :( Hi I was wondering if anyone could explain this question to me in more simple terms? And what I need to look for? It's confused me :( You are required to summarise the main energy transfer mechanisms within the Earth’s atmosphere, and most importantly to describe the effects of...

I have a general question regarding Radiation. If the net Thermal Radiation is understood to be : Pnet = Pabs - Prad= σϵA(Tenv^4 - T^4) . How is it that Pnet is negative if the environmental temp is higher than the temp of the object?

Hi guys, I'm having trouble with finding information on what energy transfer is and how it occurs, within an ehgineering context. any help would be greatly appreciated