Total energy Definition and 221 Threads

What is the total energy of the universe? I would like a gross energy, not a net energy, as I saw somewhere that the net energy of the universe is zero.

Is there a direct relation between the relativistic mass (total energy) and rest mass? In other words, can we say a proton has higher rest mass than an electron because a proton-antiproton annihilation would produce that much more energy than electron-positron one? And the ratio of energy...

During the (recently departed) matter-dominated era, the total mass of the Universe, including dark matter, is believed to have been fairly constant at around 1055 kg. This was the case in a time period from at least the CMB last scattering surface to nearly the present. Mass content is...

Homework Statement Hi I am new to this forum and offering quantum physics at A level. Can anybody help with the following problem: The rest energy of an electron is 0.511MeV. A positron created in a cloud chamber has 0.158MeV of kinetic energy. It collides with an electron at rest...

A mass of 0.5 kg is attached to the end of a massless spring of spring constant 0.40 N/m. It is released from rest from an extended position. After 0.7 s, the speed of the mass is measured to be 1.75 m/s. What is the amplitude of oscillation? What is the total energy (relative to the mass at...

Does anyone know how to calculate the total energy of magnet? Thanks!

Homework Statement A loaded ore car has a mass of 970 kg and rolls on rails with negligible friction. It starts from rest and is pulled up a mine shaft by a cable connected to a winch. The shaft is inclined at 30.0° above the horizontal. The car accelerates uniformly to a speed of 2.20 m/s in...

Homework Statement The element N has 7 electrons and 7 protons in the atom. An ion of N has all the electrons removed except 1, so it resembles a hydrogen atom with a nuclear charge of +7 e. E1(Hydrogen)= -13.6eV, r1(Hydrogen)= 5.29x10^-11m. k = 8.99x10^9 e = 1.6x10^-19 What is...

Why is the total energy of an elliptical orbit given by: E_{tot}=\frac{-GMm}{2a} Where a=semi major axis. I agree for a circular orbit I can do the following: F_c=F_g ma_c=\frac{GMm}{r^2} \frac{v^2}{r}=\frac{GM}{r^2} v^2=\frac{GM}{r} Since the total energy also equal to the kinetic plus...

Homework Statement The power supplied by a certain battery is a constant 6 W over the first 5 min, zero for the following 2 min, a value increases linearly from zero to 10 W during the next 10 min, and a power that decreases linearly from 10 W to zero in the following 7 min. (a) What is the...

I'll ask this in the form of an example. A bus is traveling at some speed and there is no wind. The bus experiences a drag force related to the pressure differential at the front and rear of the bus. Most of the divergence in pressure from ambient occurs behind the bus, where the air is...

The total energy of a pendulum is calculated either by it's maximum height (Gravitational Potential), or by the lowest point with maximum velocity (Kinetic Energy). For the significant formulas of a pendulum see http://en.wikipedia.org/wiki/Pendulum_(mathematics)" wiki page If you use the...

Alright, the problem is fairly simple actually; however, I've seen a few methods to solve this that have kind of confused me. The questions is: Consider a frictionless roller coaster with a mass of 12,000kg. If the coaster starts at rest at point A, which is 95m above the ground...

According to my physics textbook, the equation E^2=\left(mc^2\right)^2+\left(pc\right)^2 suggests that a particle may have energy and momentum even when it has no rest mass, and that the total energy then is E=pc. This strikes me as odd, since the relativistic momentum of a particle is given by...

Homework Statement (a) A light particle of mass m orbits in a circular orbit around a massive attractive centre with a potential that is given by V(r) = Cr^2 (b) Using the equations for circular motion show that the total energy of such a particle must be given by E = 2Cr^2 Use...

Homework Statement A charged particle is observed to have a total energy of 0.642 MeV when it is moving at 0.700c. If this particle enters a linear accelerator and its speed is increased to 0.980c, what is the new value of the particle's total energy? Homework Equations Rest mass...

Homework Statement An electron has a total energy equal to five times its rest energy(0.511MeV). --What is its momentum (in MeV/c)? Homework Equations E(total) = [mass(electron)*c^2]/[sq. root of (1- velocity^2/c^2)] ----I converted 2.555MeV (total energy) to 4.088e-13 J and...

Homework Statement it is a multi part problem i found most just need help on last two but gave answers to the ones i found because they are needed to determin the answer. What is the translational kinetic energy of the real system, at the instant shown in the right diagram? Ktrans =...

Hello, I have measurements of the sound intensity produced by a sound source for a given frequency (*). These measurements were taken on on a grid on an imaginary sphere around the source. From these measurements it is clear that the sound intensity is not equal in all directions. The...

Homework Statement Explain why it is possible for potential energy and total energy to be either positive or negative, but kinetic energy is always positive Homework Equations The Attempt at a Solution I'm thinking that Potential Energy and Total Energy can be opposite and take...

Homework Statement A flash attatchment for a professional camera stores energy in a capactior. When a picture is taken, all of the charge is converted to energy, and the capacitor is fully discharged. A.Assume the battery charging the capacitor is a 300V battery. When the light flashes, it...

Excuse this beginners question, but someone asked me if the Universe can appear out of nothing. I answered yes, because all the energy in the Universe cancels out to make nothing. So, conversely, out of nothing can come equal positive and negative energy. He seemed half convinced. Am I correct...

Homework Statement A solid sphere has a mass of 1.0 kg. It is rolling at a translational speed of 10 m/s. What is the total energy of the rolling sphere? I think I got the problem but I'm not sure I went about it the right way. Homework Equations I = (2/5)mr^2 KE_rot = (1/2)Iw^2 KE =...

Hello! I've just finished a discussion with my peers and lecturer on some of the postulates of QM, My lecturer said that "the total energy of any quantum mechanical system is always given by the Hamiltonian, which may be obtained by appropraite application of the classical Hamiltonian"...

Hi all, I have to compute the entropy, temperature and show that the total energy can be written as E(T,N) = 3/2*N*hbar*omega*coth(hbar*omega/(2*kT)) I have found that the temperature can be written as 1/T = k/(hbar*omega)*ln([E/N*hbar*omega+3/2]/[E/N*hbar*omega-3/2]) by...

I have a question on the Hamiltonian from a classical viewpoint. I understand that the Hamiltonian, H, is conserved if it has no explicit time dependence, in other words: \frac{\partial H}{\partial t} = 0 What I am not clear on is how one can determine whether a given Hamiltonian...

Homework Statement for this problem i found all of the separate capacitence for each capacitor, each potential difference, and each charge on each capacitor but I am not sure how to get the total energy stored for the whole system. does anybody know the correct equation Homework Equations...

Many texts and research papers seem to argue the case for the total energy of the universe being zero or constant. Indeed the Friedmann equation is often derived in books using KE+PE=constant, where the constant is zero for a flat universe. The sign of the constant also determines whether the...

Fermi energy: E_f =\frac{\hbar^2 \pi^2}{2m L^2} n_f^2 The number of states with energy less than E_f is equal to the number of states that lie within a sphere of radius |\vec{n}_f| in the region of n-space where nx, ny, nz are positive. In the ground state this number equals the number of...

Hello everyone, I hope someone can help me with this simple harmonic motion question I've been trying it for about an hour now and I think i may have found the problem but I want to run it by someone else :) I'm taking this Phsyics 12U course (Uni prep for Ontario, Canada) through correspondence...

I am looking for an expression for the total energy of a particle of rest mass m_0 that includes kinetic and gravitational potential, if there is such a thing. If I take the product of the time-components of the four-velocity and four-momentum vectors, I get m_0 c^2 \gamma^2 where...

Thermodynamics asserts that energy can neither be created nor destroyed and thus the total energy of the universe is always constant. Thus the accelerating expansion of the universe indicates that some form of energy is being converted into another form at increasing rate? Can this be explained...

Homework Statement A gardener exerts a force of 1.5 x 10^2 N (22 degress below the horizontal) in pushing a large 18 kg box of flower seeds a distance of 1.6 m. The coefficient of kinetic friction between the box and the floor is 0.55. use the law of conservation of energy to determine the...

I was presented with a very simple physics problem today which unfortunately stumped me for some reason: you have two spaceships: a cruiser weighing a ton, and a battleship weighing 100 tons. Now let's say the cruiser is moving towards the battleship at constant speed. From battleships point...

How can I measure the total energy loss of a Newton's cradle until it comes to rest. The only variables I am given are the horiztonal displacements for each swing (how far the ball travels out after it rebounds off the other balls) and the angle. I have no idea where to start, I was told I...

1. Homework Statement Plot total energy vs. time graph using MATLAB (damped system) wn(the undamped natural frequency) = 2 rad/s damping ratio, z = 0.01 mass = 10kg initial displacement = 0.1 initial velocity = 0 2. Homework Equations KE = (1/2)mv^2 PE = mgh 3. The Attempt...

Hi all. I've this problem and I'm stuck on the part where I have to find the total energy. Homework Statement A 507 g mass oscillates with an amplitude of 10 cm on a spring whose spring constant is 20 N/m. At t =0s the mass is 5.0 cm to the right of the equilibrium position and moving to the...

1. The length of a simple pendulum is 0.760 m, the pendulum bob has a mass of 365 grams, and it is released at an angle of 12-degree to the verticle. (a) With what frequency does it vibrate? Assume SHM. b) What is the pendulum bob's speed when it passes through the lowest point of the swing? c)...

Homework Statement An object of mass 2.00 kg is held at a position A, a vertical height of 20.0 m above the ground. Point B is 8.00 m directly below A. Neglect air resistance and use g=10.0 m/s(squared) What is the ratio of the total energy of the object at position A to position B? Homework...

Homework Statement A 175g mass attached to a horizontal spring oscillates at a frequency of 2.0Hz. At one instant, the mass is at x = 5.0cm and has Vx = -20cm/s. Determine the following. a.) the period b.) the amplitude c.)the maximum speed d.)the total energy Homework Equations...

I am reading from the book, "Nuclear Reactor Theory", by Lamarsh. I have run across an idea that I am struggling to understand: It states that for a neutron that scatters elastically with a nucleus, the Energy in the Center of Mass (COM) frame of reference will always be slightly less than...

Counting contributions from mass, spin, etc., is there a physical circumstance of zero total energy?

Homework Statement A 50.0 gram object, connected to a spring with a force constant of 35.0 N/m oscillates on a horizontal, frictionless surface with an amplitude of 4.00 cm. Find: a) The total energy of the system. b) The speed of the object when the position is 1.00 cm c) The Kinetic Energy...

Homework Statement Assume that the magnitude of the magnetic field outside a sphere of radius R is B = B0 (R/r)^2. Determine the total energy stored in the magnetic field outside the sphere.Homework Equations I think it's necessary to use the energy density equation. u = B^2/(2*u0) total...

If a nucleus is in its first excited state, is its total rest energy then mc^2 + Eex1?

Homework Statement A mass M is suspended from a spring and oscillates with a period of .940s. Each complete oscillation results in an amplitude reduction of a factor of .96 due to a small velocity dependent of frictional effect. Calculate the time it takes for the total energy of the...

I need with a problem...A 0.10 kilogram solid rubber ball is attached to the end of an 0.0 meter length of light thread. The ball is swung in a vertical circle. point P, the lowest point of the circle, is 0.20 meter above the floor. The speed of the ball at the top of the circle is 6.0 meters...

Homework Statement A 12 V battery is rated at 200 Ah (Amps hours). How much total energy can it supply?Homework Equations P=IV The Attempt at a Solution First I did E = 1/2 C V^2. (Got 4,320,000 J, although I'm not sure if that is correct). But now I need to convert it to kwh so my question is...

Homework Statement Can a system have the total energy conserved but the hamiltonian not conserved? Homework EquationsIf the partial of the lagrangian w.r.t time is zero, energy is conserved. The hamiltonian is found by the usual method- get the generalized momentum from the lagrangian...

Homework Statement Two point charges lie along the y axis. A charge of q1 = -12.0 µC is at y = 7.0 m, and a charge of q2 = -2.0 µC is at y = -4.0 m. Locate the point (other than infinity) at which the total electric field is zero. Homework Equations E = (K lql) / r^2 The Attempt...