Kinetic energy Definition and 1000 Threads

Homework Statement https://s2.lite.msu.edu/res/msu/perl_author/MI3/CH7/IMAGES/MI3_7P32.png The figure shows a potential energy curve for the interaction of two neutral atoms. The two-atom system is in a vibrational state (i.e., a total energy state) indicated by the heavy solid horizontal line...

1. A ball falls to the ground through the air. Is the energy of the air conserved?2. None3. When a ball falls to the ground a transformation of energy occurs. The previously stored potential energy gradually becomes kinetic energy during its fall. The energy conserved in the air is the slight...

Does the law of conservation of energy make valid predictions when energy is converted from gravitational potential energy into kinetic energy?

Homework Statement So a little background before stating the problem: During a lecture a couple weeks prior to lab, the instructor did an example where we were told to find the max height of a ball launched upwards by compressing a spring. In order to calculate that, he showed that E1 is the...

Homework Statement At a waterpark, sleds with riders are sent along a slippery, horizontal surface by the release of a large, compressed spring. The spring with a force constant k = 4300 N/m and negligible mass rests on the frictionless horizontal surface. One end is in contact with a...

Homework Statement So I'm trying to find the final velocity of a proton that is being accelerated by a particle accelerator, just before it collides with a particle. All I have is its kinetic energy just before collision: 4.7066×10^(-13) J. I thought I should use KE = 1/2 mv^2 but then...

Homework Statement Show that the quantization of angular momentum implies that the kinetic energy of the electron is quantized as K=nhforb/2, where forb is the frequency of rotation. Assume circular orbit. Homework Equations Radial acceleration: arad = v2/r = (4π2r/T = 2*π*v/Tr = nħ KE =...

Homework Statement Just a simple question, does Kinnetic enrgy applies to a bullet that has being shot?Homework Equations K=1/2 * m * v^2 The Attempt at a Solution N/A

W_{total} = \delta K What about lifting a block upward? If you lift a 10kg block vertically and bring it to a rest, you are doing work on it but the velocity in the beg and the end is 0, thus the equation says the work done on it is 0. But isn't there potential energy? Does the equation not...

Homework Statement On cart with a mass of 371 kg and another cart with a mass of 495 kg are rolling toward each other. Just before they collide, the 495 kg cart has a speed of 2.09 m/s, and the 371 kg cart has a speed of 1.90 m/s. We will consider the friction between the cart wheels and track...

http://imgur.com/luj32IE 1. Homework Statement A skier starts from rest at the top of a smooth incline of height 20 m as in Figure 2. At the bottom of the incline, the skier encounters a horizontal rough surface where the coecient of kinetic friction between the skis and the snow is 0.21. (a)...

Homework Statement [/B] Our teacher has given us the weekend to go and work on the Egg Drop project. He's restricted us to 20g total mass and 6cm * 6cm * 30cm in size. Food, foam, bubble wrap is prohibited. Parachutes can be added but can not make it exceed 12cm * 12 cm * 30cm. So that's what...

Homework Statement A 100 kg person in space throws a 1kg sphere away from their body. The sphere starts from rest and ends up traveling 10 m/s away from the person. What is the kinetic energy of the person and the kinetic energy of the sphere? Is kinetic energy conserved?[/B]Homework Equations...

Homework Statement A 15.0g bullet is accelerated from rest to a speed of 780m/s in a rifle barrel of length of 72.0cm a)Find the kinetic energy of the bullet as it leaves the barrel b)Use the work kinetic energy theorem to find the net work that is done on the bullet. (this problem had part...

Hello! I'm new to this forum but ok let's get this started, First I'll revisit the definition I know as physics; the study of nature in order to provide a reasonable(radical/rudimentary) explanation/reason. This I believe in is not quite how things are today, at school, with my teachers or at...

1. Homework Statement Homework Equations In picture The Attempt at a Solution Is my setup correct for finding the combined kinetic energy in part a)

Homework Statement Suppose a subatomic particle of mass m kg has kinetic energy K.E. a nJ and is moving southward toward a vertical wall. When the particle is distance d cm from the wall a magnetic field is turned on: it has magnitude b T and points upward. The particle turns westward so it...

Homework Statement The work function for potassium is 2 eV. Consider light with wave length 3.6*10^-7 m hitting the potassium surface. a) what is the stopping potential? b) what is the kinetic energy and velocity of the fastest electrons emitted? Homework Equations KE_max = hf - Φ q_e V_s =...

Homework Statement A 'hammer' thrown in athletics consists of a metal sphere, mass 7.26 kg, with a wire handle attached, the mass of which can be neglected. In a certain attempt it is thrown with an initial velocity which makes an angle of 45 degrees with the horizontal and its flight takes 4...

Homework Statement Suppose an atom of iron at rest emits an X-ray photon of energy 6.4 keV. Calculate the “recoil” momentum and kinetic energy of the atom. (Hint: Do you expect to need classical or relativistic kinetic energy for the atom? Is the kinetic energy likely to be much smaller than...

Homework Statement Two blocks are hung by a string draped over a pulley, a 1.5-kg block on the left and a 3.0-kg block on the right. The two blocks start out at rest and at the same height. A. What is the change in the gravitational potential energy of the system of blocks and Earth when the...

Homework Statement Find the minimum force ##\displaystyle F## required to move ##\displaystyle M_2##.Details and Assumptions: ##\displaystyle M_1 = 3Kg## ##\displaystyle M_2 = 5Kg## ##\displaystyle \mu_1 = 0.4## ##\displaystyle \mu_2 = 0.6## ##\displaystyle g = 9.8m/s^2## Homework...

Homework Statement A truck hauling a big tank of oil starts at position x=D (Chicago) and heads due west (–x direction) toward its destination at x = 0 (Des Moines). At Chicago, the total mass of the loaded truck is M and the mass of oil it is carrying is λM. (Thus M(1–λ) is the "tare" mass =...

Homework Statement A small bullet is fired into a large piece of wood. After the bullet penetrates the wood, the assembly moves as one unit along a low-friction track in the direction of travel of the bullet. A. After the bullet is stuck in the piece of wood, is the momentum of the wood (not...

Homework Statement A uranium-238 atom can break up into athorium-234 atom and a particle called an alpha particle, α-4. The numbers indicate the inertias of the atoms and the alpha particle in atomic mass units (1 amu = 1.66 × 10^−27 kg). When an uranium atom initially at rest breaks up, the...

why we assume that velocity decreases linearly in a spring (i.e. if one end is fixed, then velocity of a particle (of spring) at x from fixed =vx/l where v is the velocity of the free end) and why does it hold good too when the spring (linear mass density) is non uniform... EDIT: spring has...

Dear PF Forum, I have a question in mind. But I'm not sure if this belong to SR forum, cosmology or classical physics. So I post it here. And perhaps as some of you might have known before or thought it over. It's about kinetic energy. Supposed this... A rocket, with a rest mass 1 ton. And the...

I have a question regarding how to calculate kinetic energy. Let's say I was to find the kinetic energy of a ball shot at 180 m/s at a 45 degree angle. Do i simply sub in 180 as v (velocity) in the kinetic energy equation (1/2mv^2) or must it be split into components?

I've recently created a 3D motion generator (Anti-Gravity Transportation (AGT)) in 2D/3D design. unfortunately my current physics knowledge is not advanced enough to take this machine to its maxium potential. i can concieve perpultion and sustainable energy coming from this idea. my question...

I got a little bit confused while studying gravitational potential energy, particularly the expression for long distances: (-GMm/r). An exercise asks me for the velocity, period and radial acceleration for a 1000kg satellite that I wish to put into orbit. That's okay. But after that, I'm...

We know that If object is homogenius and small (like gold atom) we can use this equation to calculate total energy of object when it moves very slow due to speed of light.And the equation is ##1/2(m_1v^2+m_2v^2+m_3v^2...=1/2Mv^2##, ##(M=m_1+m_2+m_3...)## here v is small and we are talking about...

Hi, I'm reading a high school textbook about mechanics. It's amazing how the author draws up the problems and solves them by introducing a new consistent concept. Now I'm reading about collisions. He writes the conservation of momentum but the problem is that we have two unknowns in one...

I heard that proportionality of kinetic energy with square of velocity, ##E_k\propto v^2##, can be derived with help of quadratic forms. It goes like: we guess that ##E_k\propto v^2## and we assume that momentum ##p\propto v##, then equation is valid in another inertial system. And so on. The...

Homework Statement A charged particle (q = -8.0 mC), which moves in a region where the only force acting on the particle is an electric force, is released from rest at point A. At point B the kinetic energy of the particle is equal to 4.8 J. What is the electric potential difference...

Considering horizontal flow in a pipe (under the action of pressure forces only) if we focus on a fluid element we have a pressure gradient across the same i.e, a net pressure force will always act over the element that essentially maintains the flow.Now, in a region in the flow field if the...

For particle in the box wave function, it is the eigenfunction of kinetic energy operator but not the eigenfunction of momentum operator. So, do these two operators commute? (or it has nothing to do with commutator stuff?) How about for free particle? For free particle, the wave function is...

Dear PF Forum, I'd like to ask a question regarding a post in Relativity sub forum. The formula for kinetic energy is ##E_k = 0.5mv^2## Which makes sense. Because if we push/accelerate 1 kg object for 1 m/s2 for 8 meters, we'll spend ##E = N.m = 8 joules## How much time do we need to do that...

Homework Statement [/B] A 2.0 kg ball moving with a speed of 3.0 m/s hits, elastically, an identical stationary ball as shown. If the first ball moves away with angle 30° to the original path, determine: a. the speed of the first ball after the collision. b. the speed and direction of the...

Homework Statement 2. Homework Equations [/B] KE=1/2 mv2 The Attempt at a Solution To calculate the kinetic energy of the ball just after it leaves the surface, I use the ratio of the centre of gravities of the ball at the two different heights. My working is (0.41/0.76)×0.75 which gives me...

Homework Statement In the figure here, a block of ice slides down a frictionless ramp at angle θ=55.0 ˚ while an ice worker pulls on the block (via a rope) with a force that has a magnitude of 54.0 N and is directed up the ramp. As the block slides down through distance d = 0.400 m along the...

Homework Statement This is my first time posting here guys so correct me if I am wrong. This question was on my test and I wanted to know if I did it right. There is a block of mass m and it is moving at a certain velocity before pressing against a spring which compresses distance x. Find...

Imagine two experiments A and B. In experiment A I load a gun with a cartridge and shoot a bullet. Total energy in this experiment will be E(heat) + E(projectile). I include recoil in E(projectile). E(heat) in its turn will heat the muzzle and some air. Done. In experiment B I do...

This is mostly a conceptual confusion I'm having, not a specific problem, so it didn't seem like it'd fit under homework problems. I'm having trouble understanding when potential energy should or shouldn't be used in a energy conservation equation. When looking at a problem with a skier going...

I have always found the Newton's Cradle that my daughter bought for me fascinating. With the steel balls as identical as possible then the analysis of the process is simple. Both the momentum and kinetic energy are conserved (assuming negligible losses) on collision. The only way(?) this can...

Hi, new here, so I hope I'm doing this correctly. I'll keep this question as brief as possible, but it requires just a bit of setup. I'm not an engineer or physicist, but do have a more than decent layman's understanding. I've lately become fixated on the game of bowling (ten pin), and have...

hi I have been given an assignment at school to look at various ways heat is transferred through liquids. I'm interested in looking more into the kinetic energy of molecules and how their vibration causes heat, I would like to know if there is a device I could use to record the frequency of...

I know there are some threads discussing about the Lorentz force equation but this is something different I came across and I couldn't find anyway to derive that formula. To be specific I'm talking about a charged particles in a magnetic field, where F=vqB and everything that is moving has...

There is 14 km of tunnel of 7.7 m diameter, full of water traveling at 3.75 m/s,that represents approximately 8000 Megajoules of kinetic energy. How? Calculate it to prove (Taken From Wikipedia under topic of "Water Hammer".

I know that kinetic energy depends referance frame is there any article about this issue thanks ?

Homework Statement Lets say we have a series of balls and an eggs. All items have equal mass but are traveling at different velocities. Thus they have differing kinetic energies. Now, for each 'ball' object we have, we want to find an egg object with a similar kinetic energy. Let's say...