Kinetic energy Definition and 1000 Threads

I got a question towards kinetic energy and elektrical energy. They always talk about about particle accelerators or devices when talking about transformation of elektrical energy into kinetic energy of elektrons. But do elektrons also have kinetic energy when they are circulating in an...

So basically, I was doing my AP Physics 1 homework and came across the spinning ice skater question yet again. The question states, "An ice skater is spinning about a vertical axis with arms fully extended. If the arms are pulled in closer to the body, in which of the following ways are the...

Hello all! I am new to this forum, though I have been lurking for a long time. I intend to fill out my profile and introduce myself, but finals leave me with little time to spare at the moment. I have this final next week and would like to sort this out beforehand, hence the hasty post! Thank...

Homework Statement Problem: Consider a "crystal" consisting of two nuclei and two electrons arranged like this: q1 q2 q1 q2 with a distance d betweem each. (q1=e, q2=-e) a) Find the potential energy as a function of d. b) Assuming the electrons to be restricted to a one-dimensional...

Homework Statement Consider the nuclear decay 21486Rn → 21084Po2- + α. Calculate the Q for this decay, and give the value of the kinetic energy of the alpha particle in the rest frame of the Rn nuclide. The rest mass of the Rn nuclide is 213.9954u, of Po is 209.9829u, of α is 4.00015u and of...

Can someone someone explain and possibly draw a free body Diagram. kinetic energy of an object has the same direction as its acceleration

Homework Statement A bullet leaves the barrel of a gun with a kinetic energy of 90 J. The barrel of the gun is 50 cm long. The gun has a mass of 4 kg, the bullet 10 g. (a) Find the bullets final velocity. (b) Find the bullets final momentum. (c) Find the momentum of the recoiling gun. (d) Find...

I find difficulties in identify the forces acting behind the acceleration of objects that are considered consequence of conservation principles (for istance of KE and angular momentum). I'll make an example to explain. The same string-mass system is linked to a rod. In case (a) a force pull the...

For a photon the energy is given by $$E = h\nu$$ Does this includes both kinetic energy and energy due to mass? If so then de Broglie gave the equation λ = h/p by equating hν with mc2 but since E = mc2 just gives the energy due to relativistic mass at that speed it would not include kinetic...

Homework Statement 1.) A 1200 kg car traveling at 20 m/s collides with a stationary 1400 kg car. The two cars lock together. Determine the speed of the vehicles immediately after the collision if 80% of the initial kinetic energy is converted to heat and sound during the collision 2.) Must all...

why does kinetic energy depend on half the square? if we add up all the velocities does it not produce half a square?

Consider a collision between two point particles, with no external forces acting on the system. Linear and angular momentum of the system are always conserved, while the kinetic energy of the system is conserved only if internal forces acting in the collision are conservative. This last point...

Homework Statement Pretty simple question, just checking for confirmation. It was a small question at the beginning of a summative test, a rock was dropped off of a bridge and we were asked to graph the kinetic energy over time. Homework Equations 1/2mv^2. The Attempt at a Solution I...

Homework Statement A sample of hydrogen atoms is irradiated with light with wavelength 85.5 nm, and electrons are observed leaving the gas. (a) If each hydrogen atom were initially in its ground level, what would be the maximum kinetic energy in electron volts of these photoelectrons? 0.9 eV...

Homework Statement A beam of ultraviolet light with wavelength of 200 nm is incident on a metal whose work function is 3.0 eV. Note that this metal is applied with +1.0 V with respect to the ground. Determine the largest kinetic energy of the photoelectrons generated in this process. Homework...

While studying energy on Sears & Zemansky's University Physics, I came up with a doubt on the meaning of kinetic energy. The book gives two possible physical interpretations of this quantity. I'm okay with the first meaning of KE but I don't understand completely the second one. I don't...

Homework Statement There is a Ball that weights .150 kg and is moving at 90m/s =607.5 Joules and it is moving to the right, so its coming from the left. on the opposing side is a 35kg cart moving at 4.5m/s = 354.37 Joules The Cart has superior momentum and mass... however, in this scenario some...

Entropy is basically a measure of the number of avaible microstates a system can have, given a certain energy of the system. It is a measure of the uncertainty of the exact state of the system. Now, suppose we have a box with a single particle inside and with the only internal energy being the...

If an electron in an excited wave form passes thru an electric field , can it lose kinetic energy in doing so.?

Hello, I want to make sure I understand the following considering ideal gases. Assuming I have two different types of gases, say, O2 and H2 (each at thermal equilibrium), is it correct to say that the kinetic energy of the O2 gas equals to the kinetic energy of the H2 gas since they're both...

In the Hamilonian for an H2+, the kinetic energy of the electron (KE of nucleus ignored due to born-oppenheimer approximation) has a negative sign in front of it. I understand the signs for the potential energy operators but not for the KE apart from the strictly mathematical point of view. Can...

Hello, I tried a different route to derive relativistic kinetic energy and I cannot see why it doesn't work. Here is my work: 8.00000000000000E+01 RM, Rest mass of object 7.50000000000000E+05 v, velocity of object 6.00001877636573E+07 Momentum, p,= RM/Sqrt(1-(v^2/c^2))*v...

Homework Statement I am looking at part C.[/B] https://scontent-ord1-1.xx.fbcdn.net/hphotos-xal1/v/t34.0-12/12782422_10205657311624690_1648245885_n.jpg?oh=79b686a8b74392888fab0b070b86627d&oe=56F7E1E4 The Attempt at a Solution Here I am looking at part C. My initial thought is that they have...

I'm trying to prove that kinetic energy is not conserved in inelastic collisions using the conservation of momentum. This is the set-up. An object A of momentum ##{m_1}{v_1}## collides inelastically with object B of momentum ##{m_2}{v_2}## using momentum conservation ##P_i = P_f## {m_1}{v_1} +...

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 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...

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...

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...

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 I need to explain for a lab, why the efficiency of a rubber band slingshot constant for different stretch lengths. I don't need math, just a general explanation of why kinetic energy of projectile/elastic potential energy in rubber band is constant. Homework EquationsThe...

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...

Im sure Imma mess this up, probably because I am really tired...but I have a bullet that weights .015kg's and is moving at 285m/s, so 609.18J's as with KE. I hit a 70kg block, penetrates .3048 meters thus exerting 1998.62N's of force, which is a lot of force. .3048/285m/s so 0.00106 seconds...

If I have a bullet with 700 Joules KE, the mass is 0.008036m, velocity 417.39m/s, momentum p=3.35kg-m/s Kinetic energy is the ability to do work, Kinetic energy converts into FORCE...so yes KE will exert a force...which will do work, as to do work requires force and distance. Thus, when the...

I was wondering something, I dropped a box onto my glass desk but it didn't bounce back, I also hit a hammer against a rigid wall, the matter smacked into the wall, it has KE. It never bounced back, I didn't see any deformation or rebound in either situation, I wasn't hitting too hard nor...

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...

Mentor note: Thread got moved to the homework section How close can two protons get if one is at rest and the other has a kinetic energy equal to the average energy at T =107 K? I know that the kinetic energy of the moving proton is 3/2kT, but what is the kinetic energy of the proton at rest...

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...

I'm currently in High School and we have to create an idea to make the world better. Mine is to use the force of gravity and convert it to energy to power a system that will filter air. This is supposed to be used in developing countries where there are large amounts of biomass and harmful...

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...