Kinetic Definition and 1000 Threads

First of all i am not a native speaker so i apologize for my english. Kinetic energy is velocity squared multiplied by mass, whereas momentum is just velocity multiplied by mass. I have read that the reason for this is because conservation of kinetic energy is related to symmetry of the motion...

I want to write the kinetic energy operator as a matrix within a finite element approach for electrons moving in a crystal with some effective mass that is a function of position. Now usually we have: K = -ħ2/2m d2/dx2 such that the second order derivative of a wavefunction maybe written as...

Homework Statement The average kinetic energy of water at 0 °C is __________ the average kinetic energy of ice at 0 °C. Homework EquationsThe Attempt at a Solution I said that it is greater than because when ice melts, energy is added to break the potential energy (bonds). I also know that...

Homework Statement A particle of mass M is released from rest on a rough inclined plane, which makes an angle of 30° with the horizontal. It is observed that the particle moves a distance of 3 m in 3 s. What is the particle’s acceleration? Draw a properly labelled free body diagram. Calculate...

Homework Statement At what speed the kinetic energy of particle equal n times it's rest energy Homework Equations i use this equation ##T=(\gamma - 1)m_{0}c^{2} ## The Attempt at a Solution ##T=n(m_{0}c^{2})## ##n=\gamma -1## ##\gamma =n+1## ##\frac{1}{\sqrt{1-\frac{v^{2}}{c^{2}}}}=n+1##...

A balla of mass 5 kg is dropped from a height of 10 meters. What is the kinetic energy after 1 second has elapsed?First i found the velocity using this equation V^2=2gh = 14m/s Then I used this equation to find Kinetic Energy KE=1/2mv^2 and got this 490 J. But i don't know how to find KE...

So, i have some questions, they might sound simplistic or fanboyish even, i apologize beforehand for that! I cannot reveal anything more at this point, sorry :D I would need some realistic assesments of a simple rod, launched from low orbit, designed to take out a city or more... Would need in...

energy. Consider a particle in a box of the form ##V(x)= \begin{cases}0 \; \; \; -L < x < 0\\ V_0 \; \; \; 0<x<L\\ \infty \; \; \; \text{ elsewhere}.\end{cases}## One can show that the probability density ##P(x) = \Psi^* \Psi## is greater in the region of lower kinetic energy (that is at higher...

Homework Statement Respected Physics Gurus/experts...! I am confused in the application of Kinetic energy Expression, i.e, KE = (1/2)MVCM2+(1/2)ICMω2 I had been trying out this question actually(it's pretty simple though:-p)...--- "A rigid body is made of three identical thin rods each of...

Probably a stupid question, but I do not get it... Here you can see an experiment demonstrating the Gaussian gun: Here I understand how momentum is conserved, i.e. the smaller mass of the ejected ball times its high speed is equal the bigger total mass of the recoiling masses times its...

I am doing a course on statistical mechanics and we are using the textbook by Mehran Kardar. We are currently dealing with a chapter on kinetic theory. The problem is, I find the exercise problems to be quite tough (and many of my classmates agree with me), and there are no good solved examples...

Hello everyone! I have a (supposedly) calculus problem that I just can't seem to figure out. Basically, I'm trying to understand why alternative kinetic energy formulation does not yield the same equations of motion in problem 11 of Goldstein's Classic Mechanics 3 edition. The text of problem...

Hello, I would like to provide my thoughts on the distinction between KE and p and would like to know if this reasoning is sound and objective. I will give an example to start: A bowling ball is dropped from some height into a pool of honey. It is observed that the bowling ball has a velocity V...

I have really problem with equation of the root – mean – square (rms) speed of the gas molecules when we use the universal gas constant (R) mentioned in all references. Accordance to all reference books, we have below equation for the total translational kinetic energy: Vrms = (3RT/ M)^0.5...

Homework Statement You are trying to slide a sofa across a horizontal floor. The mass of the sofa is 200 kg, and you need to exert a force of 350 N to make it begin to move. a) Calculate the coefficient of static friction between the floor and sofa b) after it starts moving, the sofa reaches a...

why were quantities like momentum, force , potential energy, kinetic energy,work ,etc needed to be introduced in physics? and why were they defined the way they are defined?. would it not be possible to explain nature without defining these quantities or by using alternate physical quantities ?

is it right to say, "when all the potential energy is converted in kinetic energy the object is moving at the escapevelocity. and "when the change in potential energy and kinetic energy is constant at the same time it is laying still on the ground or in a perfect circulair orbit. and the last...

Homework Statement A piece of taffy slams into and sticks to another identical piece of taffy that is at rest. The momentum of the two pieces stuck together after the collision is the same as it was before the collision, but this is not true of the kinetic energy, which is partly turned into...

Homework Statement This is a more than one part question that depends on answers from the previous parts, which I have so I will not rewrite those questions. I will write the question I am facing difficulty with: Answers from previous parts: Length = 1.95 m (From top of chains to center, its...

Finding the maximum kinetic energy in a simple parabolic projectile motion requires us to find the maximum velocity. I know that the velocity will be maximum at two points, the point of projection and point of return. So there must be two points where the kinetic energy is maximum. But my...

If light of certain wavelength falls on two particles say electron and a neutron(isolated) then since they are absorbing the same amount of energy their kinetic energy must be same. But using the formula: $$ \lambda = \frac{h}{\sqrt{2mE}} $$ we get $$ E = \frac{h^2}{2m \lambda^2}$$ which states...

Question in my textbook:- The wavelength of light from the spectral emmision line of sodium is 589 nm. Find the kinetic energies of electron and neutron at which they both have same de broglie wavelength. Logically, since light of same energy is falling on both then their kinetic energies must...

I am having trouble wrapping my head around a physics concept. If we roll solid sphere down an inclined plane it will reach the bottom at a different time than if we were to say, roll a hoop down the same inclined plane. This is because they have different rotational inertias, and so more of...

Homework Statement A trolley of mass 0.5 kg rolls along a level, frictionless ramp at a velocity of 6.0 m s-1. It collides with a second trolley of mass 1.0 kg which is initially at rest. The first trolley rebounds with a speed of 2.0 m s-1 . a) Stating clearly any principles involved, find...

Homework Statement This problem comes from an intermediate step in the textbook's derivation of relativistic energy. It states that E_k\:=\:\int _0^u\frac{d\left(\gamma mu\right)}{dt}dx then leaves the following intermediate calculation as an exercise to the reader: Show that...

On very small scales, an object's kinetic energy tells you its temperature, and on larger scales, an object's kinetic energy tells you its velocity. Where's the cut off? I mean, velocity is relativistic, but temperature... isn't... is it? Also, black body radiation decreases a body's temperature...

I see that black body radiation slowly depletes a body's thermal energy, which is just another way of saying that black body radiation depletes the kinetic energy of a body's constituent particles. But does black body radiation also cut into the kinetic energy of the body as a whole, such that a...

So I understand that thermodynamics of a chemical reaction is the change in Gibbs free energy and that kinetics mainly deal with the activation energy (or production of a high energy intermediate). My question comes from something that my organic chemistry professor stated in class. He said...

Can anyone please let me know an example where a body has large mass but low Kinetic Energy? Please provide some reasons for same.

Homework Statement I have solved the problem where one mass m1 is on a horizontal frictional table connected to a mass m2 which is hanging off the table by a string over a pulley (assuming pulley massless), assuming that m2 is greater than m1 there is a net acceleration causing the mass 2 to...

Homework Statement Calculate the deBroglie wavelength of a proton moving at 1/4 the speed of light. How does the kinetic energy of this proton compare to its p^2 /2m? What does p^2 / 2m anyway conceptually (isn't it one of the triangle thingies in the lower version of E=mc^2)? Homework...

1. A ball hanging on a pendulum hits an object standing on the table. The interaction is elastic and linear. After that, the object falls on the floor. Homework Equations From state 1 to 2, we have the conservation of the potential energy of the pendulum to its kinetic energy, right before...

The mass of a particle will increase as its velocity increases according to special relativity. This has been confirmed in countless experiments in which particle accelerators accelerate charged particles. What type of experiments have confirmed this for uncharged particles? Thanks in advance.

Hello 1. Homework Statement In a uniform solid cylinder of radius r, mass m and height h we emptied a cylindrical cavity of radius r/4 tangent and parallel to the symmetrical axis z of the original cylinder. The cylinder is rolling without slipping on a horizontal plane. Find the kinetic energy...

Hi guys, I got one confusion when reading Goldstein's Classical Mechanics (page 20, third edition). After getting the equation, then it says that Note that in a system of Cartesian coordinates the partial derivative of T with respect to qj vanishes. Thus, speaking in the language of...

Homework Statement An object has a mass of 10 lbm. b. Find the change in kinetic energy ft·lbf when its velocity decreases from 50 mph to 15 mph. Homework Equations KE=1/2mv^2 Ke=(ft*lbf) 1MPH=1.4667 ft/s The Attempt at a Solution When calculating this, does it need to be in slugs, lbm, or...

It's my first post so big thanks in advance :) 1. Homework Statement So the question states "By interpreting <pxΨ|pxΨ> in terms of an integral over x, express <Ekin> in terms of an integral involving |∂Ψ/∂x|. Confirm explicitly that your answer cannot be negative in value." ##The 'px's should...

Homework Statement Determine the maximum kinetic energy of a uniform rod of mass 0.5Kg and length 0.75 that has an angular displacement of 5 degrees. Homework Equations y = rsin (x) where x is the angular displacement The Attempt at a Solution Using conservation of energy ETotal = EMech +...

When a body is in motion , does kinetic and static friction act simultaneously

Homework Statement I am trying to get the hamiltonain operator equality for a rigid rotor. But I don't get it. Please see the red text in the bottom for my direct problem. The rest is just the derivation I used from classical mechanics. Homework Equations By using algebra we obtain: By...

Homework Statement A man pulls a 15-kg sled containing a 5.0-kg dog along a straight path on a horizontal surface. He exerts a force of 55 N on the sled at an angle of 20.° above the horizontal, as shown in the figure above. The coefficient of friction between the sled and the surface is 0.22...

Homework Statement I need to rearrange the change in kinetic energy equation for mass Homework Equations Change in Kinetic energy = 0.5mv^2-0.5mu^2 The Attempt at a Solution I factorised the right hand side to give: Change in kinetic energy = m(0.5v^2-0.5u^2) Then: m = Change in...

I would like to calculate the electron kinetic energy ejected from a cathode as a function of the electric field and pressure without known of the temperature and velocity.

Does rolling friction depend on the surface area? In other words, the size of the object placed? If I had a block and sphere of the same mass. Without static and kinetic friction coming into play. Which would experience greater rolling friction if they were on the same incline and of the same...

Homework Statement One mole of oxygen at 27°C and at one atmospheric pressure is enclosed in a vessel. Assuming the molecules to be moving with Vrms, find the number of collisions per second which the molecules make with 1 m2 area of the vessel wall. Homework Equations vrms = √(3RT/M) PV = nRT...

Hi all, I have charged particles (protons) accelerated by an electric field. If I add up all the momentum and find the change in momentum per sec I can find the acceleration of my craft by dp/dt /M = a If I add up all the kinetic energy of the particles and find the KE per sec, I can find the...

Homework Statement A Physics textbook weighing 3 kg needs must be launched into a nearby trash can. The velocity necessary to accomplish this feat is 4 meters per second when unleashed in its flight. Assume no wind resistance. What energy is necessary to accomplish this deed? Homework...

Homework Statement A toy car coasts along the curved track shown. The car has initial speed VA when it is at point A at the top of the track, and the car leaves the track at point B with speed VB at an angle θ above the horizontal. Assume that energy loss due to friction is negligible...

Hello, I have this problem statement : "Due to air drag, the radius of a satellite’s circular orbit decreases from r to r - △r, where the positive quantity △r is much less than r. The mass of the satellite is m. Show that the increase in orbital speed is △v = +(△r/2)[(GM/r^3)^1/2]; that the...

Hello PF. I have a question on a concept of Potential and Kinetic energy. So for this let's take a ramp and a ball at the bottom. If I apply a force on the ball to make it go up the ramp, when it starts to move it will gain kinetic and potential gravitational ( I think ) but what about at the...