In physics, energy is the quantitative property that must be transferred to a body or physical system to perform work on the body, or to heat it. Energy is a conserved quantity; the law of conservation of energy states that energy can be converted in form, but not created or destroyed. The unit of measurement in the International System of Units (SI) of energy is the joule, which is the energy transferred to an object by the work of moving it a distance of one metre against a force of one newton.
Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object's position in a force field (gravitational, electric or magnetic), the elastic energy stored by stretching solid objects, the chemical energy released when a fuel burns, the radiant energy carried by light, and the thermal energy due to an object's temperature.
Mass and energy are closely related. Due to mass–energy equivalence, any object that has mass when stationary (called rest mass) also has an equivalent amount of energy whose form is called rest energy, and any additional energy (of any form) acquired by the object above that rest energy will increase the object's total mass just as it increases its total energy. For example, after heating an object, its increase in energy could be measured as a small increase in mass, with a sensitive enough scale.
Living organisms require energy to stay alive, such as the energy humans get from food. Human civilization requires energy to function, which it gets from energy resources such as fossil fuels, nuclear fuel, or renewable energy. The processes of Earth's climate and ecosystem are driven by the radiant energy Earth receives from the Sun and the geothermal energy contained within the earth.
Hello!
So here what I did is first calculated the potential energy; $$ E_p = \frac{1}{2} * k * x^2 $$ E_p should be = 0,125 J Now i tried calculating the kinetic energy, I used this formula $$ E_k = \frac{mv^2}{2} $$ to get v I used this formula $$v = x *\sqrt{\frac{k}{m}} $$ v should be =...
In Example 41.5, they are implying that, for a hydrogen atom, if the orbital quantum number ##l## goes down the electron will lose energy. However, they said nothing about the principal quantum number ##n## going down, so there should be no loss in energy. As far as this book has presented, the...
So I read that Bohr's atom has discrete energy levels that an Electron can orbit at and that each level has n amount of sublevels (if n = 2 then there are 2 sublevels). Does the sublevel that the Electron is in have to do with it's mass? Does an electron in energy level l and sublevel d have...
I'm trying to complete this past exam paper Q.
Water volume = 200hl = 20000L
1L=10^-3 m^3
20000L = 200 m^3
Density of water at 15 deg C = 999 kg m^3
Density = Mass/Volume
999 kg m^3 = Mass/(200 m^3)
Mass of water = (200)(999) = 199800 kg
Heat required to to heat 199800 kg water:
Q =m C dT
=...
In most textbooks, the recoil energy of the nucleus is ignored as it absorbs so little energy, and since its main role in the reaction is to absorb some of the photon's momentum without absorbing much energy.
I'm tempted to say that the nucleus gets the maximum energy when the kinetic energy of...
Suppose we have a molecule A-A and a molecule A-B . And we want to compare the differences in energy of the different molecular orbitals for example the 1s antibonding orbital with the 2s bonding orbital.How can we do that?
In using scintillator or germanium energy sensors, certain radionuclides representing some definite line energies are used to calibrate the sensors. What technique or method is used to measure or determine the energies of these standards.
How can we calculate the energy of a hole or an electron in p and n type semiconductors?
Which are the contributions from different sources we must take into account? I know it is the dopant and base but if we change one of them how that changes it ? Maybe the interatomic distance has...
In ΛCDM, H(t0) = 70km/s/Mpc,
Ωd(t0) = 0.3, Ωr(t0) = 0 and ΩΛ(t0) =0.7,
so that Ω(t0) = Ωd(t0) + Ωr(t0) + ΩΛ(t0) = 1and the universe is spatially flat.
I want to know the t and z when the matter density equal to the vacuum energy density. By total energy density equation, I think Ωd(t) +...
Thank you for reading :bow:
Section 1
To find the energy states of the particle, we define the wave function over three discrete domains defined by the sets ##\left\{x<-L\right\}##, ##\left\{-L<x<L\right\}##, and ##\left\{L<x\right\}##. The time independent Schrodinder equation is...
The figure is as shown below
a. From 0< t < t1 => 0 <t<4ms, the transistor is "ON"
The circuit will become like this
The current ##i_s = i_L##. To know the magnitude of the current ##i_L## do i need to know the impedance of the inductance or since it is DC voltage the impedance is not...
For one-dimensional binding potential, a unique energy corresponds to a unique quantum state of the bound particle. In contrast, a particle of unique energy bound in a three-dimensional potential may be in one of several different quantum states. For example, suppose that the three-dimensional...
I am currently studying Electrical Engineering and I have this question: An energy band is formed by the overlapping of atomic orbitals of atoms coming close to each other.I suspect that if the energy of the atomic orbital of the valence electrons of a chemical element is less than the energy of...
So force on a current carrying wire = ILxB.
If I have a bunch of bar magnets making a uniform magnetic field of strength B, then a 1 meter long wire of 0 ohms carrying 1 Amp, the force on that wire is (1)(1)xB = 1B. If I let that force move the wire for a time T, let's assume the wire moved a...
Hi,
In Problem 9.12 of Griffiths Introduction to Electrodynamics, 4th edition (Problem 9.11 3rd edition), in the problem, he says that one can calculate the average energy density and Poynting vector as
using the formula
I don't really understand how to do...
I try to use relativistic energy equation:
$$E'=\gamma mc^2$$
But, I use
$$\gamma=\frac{1}{\sqrt{(1-(\frac{v'}{c})^2}}$$
then I use Lorentz velocity transformation.
$$v'=\frac{v-u}{1-\frac{uv}{c^2}}$$
At the end, I end up with messy equation for E' but still have light speed c in the terms. How...
The expectation value of the kinetic energy operator in the ground state ##\psi_0## is given by
$$<\psi_0|\frac{\hat{p^2}}{2m}|\psi_0>$$
$$=<\psi_0|\frac{1}{2m}\Big(-i\sqrt{\frac{\hbar mw}{2}}(\hat{a}-\hat{a^{\dagger}})\Big)^2|\psi_0>$$
$$=\frac{-\hbar...
Summary:: Design compressed air energy storage for PV plant
[Mentor Note -- Thread moved from a technical forum, so no Homework Template is shown]
Hi All
For a PV project of 5 kW, we will use a CAES.
The preliminary design will consist of a compressor - 2 heat exchanger - Air receiver - air...
Hi,
I understood that to calculate the available energy in these two reactions could be calculated from Ed = [Mn(X) – (Mn(Y) + m(e))] c^2, but when I have to change use the atoms' mass instead of the nucleons' mass, it gives out two different formulas :
Ed = [M(X) – M (Y)] c2 for β-
Ed = [M(X)...
A baseball is thrown and lands 120 m away. While the ball is in flight, assuming the effect of air friction is negligible, which of the following is true?
a. At maximum height the ball has its greatest kinetic energy.
b. The horizontal component of the baseball’s kinetic energy is constant.
c...
Five electrons are in a two-dimensional square potential energy well with sides of length L. The potential energy is infinite at the sides and zero inside. The single-particle energies are given by (h^2/8mL^2) (nx^2+ ny^2) where nx and ny are integers. The energy of the first excited state of...
Now before i take a ton of beating I'm not a Physicist this thread was a google command away looking for a physicists. I am an entrepreneur from the Blockchain world and before that the IT world. Now with the Current World Economic Forum, green bonds and saving our planet conversations i would...
Could directed energy fundamentals be used in active confinement by hybridizing the heating system with directed energy. I'm sure I'm wrong in this because I only have my high school diploma.
I am trying to calculate the energy within an electric field that is generated between two plates by a pulse but am unsure of what voltage value to use. The pulse is a sinc wave.
I am assuming I can still use the equation ## E= \frac{1}{2}CV^2 ##. I know the ##V_{rms}## and ##V_{max}## which...
If the high energy ion spectra is similar to that of Maxwell-Boltzmann distribution, possible to consider it as High Energy Maxwell-Boltzmann distribution?
The ion spectrum is obtained due to the electric discharge in gas; and the peak energy is 30 keV and end point energy is 1.5 MeV and it is...
In every book I checked, the energy (per unit mass) of elastic deformation is derived as follows:
## \int \sigma_1 d \epsilon_1 = \frac{\sigma_1 \epsilon_1}{2} ##
and then, authors (e.g. Timoshenko & Goodier) sum up such terms and substitute ##\epsilon ## from generalised Hooke's law i.e.
##...
Hi,
In my textbook it says that if you consider the electrostatic repulsive barrier that protons in the Sun need to overcome in order to get into the range of the strong nuclear force to fuse together then it fails to fully account for the measured power output of the Sun.
It says that the...
When reconstructing traffic accidents to obtain the collition velocities it is needed to obtain the "crush energy" which is the amount of kinetic energy transformed into permanent damage to the cars involved. From that kinetic energy we get the Energy Barrier Speed which is used with the...
Earlier today I've attended a physics exam and there is a query I'm not sure about.
A metallic cube (specific heat capacity 30 cal/K*Kg ) falls from an height of 50 m on a non-conducting surface, and it stops. After the inelastic collision, what is the temperature of the cube?
a_ The...
Article: https://phys.org/news/2021-01-covid-lockdowns-drove-older-australians.html --
Older Australians are having problems with energy poverty. Because COVID has forced them to stay at home and inside, heating and mostly cooling costs have increased by as much as 50%. Instead of going to...
My book uses ##1/2m_1v_{1c}^2+1/2m_2v_{2c}^2=1/2m_1v_{1c}'^2+1/2m_2v_{2c}'^2## to show that the angles of deflection of the collision between two particles are the same in the centre of mass frame. However, I am doubtful that one can apply the conservation of energy to a "moving" system because...
imagine two flat plates, the upper one moving with speed v in the +z direction, the lower one is stationary
is the upper plate inserting work (per unit time) on the fluid system or the system exerting work on the plate?
or both? why they don't cancel each other e.g if the fluid is receiving work...
When an oscillator produces waves - let's say they are highly focused - that are damped by a second negative phase oscillator, where is the wave energy? The energy in each set of waves must still exist. Has it become hidden?
Background: self-studying. Very confused. Here are some initial questions I have about the photoelectric experiment. Some more may pop up later.
1. The book says we know photons exist due to energy considerations (such as emission or absorption). They also say that this photon energy is...
This is very much, a ... what's wrong with this approach...
Consider a large mass with no atmosphere, i.e. the moon. On it, construct a tower of arbitrary height. On the tower build an energy to mass machine, to convert energy to mass via E=mc^2. Once the mass is created, drop it from the...
Hey peeps,
Ok, so I need some help here. I've just been watching some videos explaining the existence of dark energy and dark matter - something which has always fascinated me.
These videos pose the theory that for the first 9 billion years of the universe dark matter ruled but, for the last...
Could I put this on here for answers please ? If produced a solid glass beam with a spiral column thorough the middle of it would the core be hotter or cooler than the surrounding air? If colder could it be use in conjunction with ground source technology to produce hot water? I not sure how to...
I will quote this statement from another thread:
In that thread number of other posters seemed to agree with this statement. So I tried to analyze it a bit.
For the sake of my questions let's say we limit GR to Schwarzschild spacetime and if there are problems with gravitational potential...
From an excel file I can get the probability of each energy state Εi and I saw at Wikipedia that the probability of each energy is proportional with
e^−Εi/KT, from this I find the energy of every micro state. Also from the formula which I found on a paper I can get a curve like the curve...
Consider two massive charged objects at rest with a large horizontal distance ##d## between them (object ##1##: mass ##m_1##, charge ##q_1## and object ##2##: mass ##m_2##, charge ##q_2##).
I apply a constant vertical force ##\vec{f_1}## upwards to object ##1## so that it gains an acceleration...
Hello!
I was reading two things:
1) tidal locking (as explained in the Wikipedia article:https://en.wikipedia.org/wiki/Tidal_locking
where it is stated that, because of internal friction caused by the body of water being attracted to the moon and deforming, the kinetic energy of the system...
Summary:: How internal energy changes in a acclerated cabin.
There are two tourus shaped insulated closed pipes containing equal amounts of ideal gas under same conditions.
B has a adiabatic partion wall.
If both are to change angular velocity by w radians per second.
How internal energies...
I have a doubt about the first request:
I suppose to find the minimum energy of ##\gamma## in the situation where ##p## is stationary, there is no reason to say that the proton is stationary if I were to calculate it in the CM, right?. So I have to consider che LAB-frame to find ##E_\gamma##...
Hello,
I am trying to correctly interpret the energy diagram below.
For example, a diatomic molecule can translate (kinetic energy), rotate (rotational energy), vibrate (vibrational energy). Each different type of energy is quantized and has associated modes (also called states). The...
Hi,
To compute, for example, the Gibbs energy change for a ligand binding to a protein, various so called alchemical methods are used in molecular dynamics simulations. My question is why can't we just obtain averaged Gibbs energies for 1) the free ligand and protein in the same water box, and...