Kinetic energy Definition and 1000 Threads

How would one find the velocity of this electron. Is it considered relativistic or will 1/2mv^2 work just fine??

In my theoretical mechanics class, we went over some very basic conservation laws (namely momentum) and talked about colliding masses. Say you have 2 masses, m1 and m2. m1 is moving to the right (towards m2) with velocity v. m2 is stationary. After the two masses collide, m1 recoils with...

Just read in Taylor that in general the kinetic energy can depend on position as well as velocity. I believe him, but how is that true? I thought it only depended on velocity. Chris

Hi everyone. I'm quite troubled with this physics question. A .035 kg bullet is fired from a .23 m barrel. The bullet experiences a force of 4500 N while in the gun barrel. What is the kinetic energy of the bullet as it leaves the gun barrel? I don't understand how to figure out the...

Homework Statement SolvedHomework EquationsThe Attempt at a Solution Solved

Homework Statement Consider a solid disk of mass m and radius R rolling along a horizontal surface with the center of the disk moving horizontally with a speed v. The total kinetic energy of the disk is a combination of translational kinetic energy , KEt and rotational kinetic energy, KEr...

When you compute the average potential energy of a horizontal spring mass system from the mean position to the positive amplitude A, the value comes to be (1/6)kA^2. For the average kinetic energy over the same range and direction, it is (1/3)kA^2, which is double the average potential energy...

Definition/Summary Kinetic energy (KE) is energy associated with movement as a whole (linear or rotational or both). Kinetic energy of a body therefore does not include thermal energy (associated with internal movement, of its molecules), nor any other form of potential energy (such as...

I knew this may not be possible, but I was wondering if you can compare kinetic energy with the energy that makes up mass? When I say that, I mean the mass of our atoms that is represented by a quantity of energy.

The kinetic energy of an object can be expressed as KE=mc^2(\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}-1) (1) For speeds much lower than the speed of light however, we know that KE=\frac{1}{2}mv^2 (2) The second expression can be derived from the first one using binomial expansion of the term with the...

Homework Statement The rotating drum on a clothes washer has a rotational inertia of 1.2 kg*m^2. In the spin cycle, it rotates at 240 rev/min. (a) What length of time is required for a 0.25 hp motor to bring the drum to this rotation rate starting form rest? (b) If the angular acceleration is...

Average kinetic energy of a molecule is = (3/2)kT Avg. K.E is directly proportional to temp.(T) only. As you increase temp of gas then K.E will also increase. In my book given that, Average K.E is independent of pressure, Volume or nature of the gas. When you increase the pressure...

I know that . Average kinetic energy of a molecule is (f/2)kT (for translational motion.where f=3 ) In my textbook given that... If the degree of freedom of the gas molecule is f then the average heat energy of each molecule of the gas is = E(avg.) = (f/2)kT which is same as the...

Homework Statement Hi! Task is to calculate kinetic energy of a projectile and cannon recoil velocity. known data: -mass of antiaircraft cannon: 3t -max horizontal distance: 4km -mass of a projectile 2kg barrels: 2 The Attempt at a Solution Since there is no initial velocity or time or max...

Why the kinetic energy is same as internal energy of ideal gas?

Hi all, Here is the derivation of kinetic energy from Work: W = ∫Fds From the second law of motion F = dp/dt, which is equal to mdv/dt, so: W = m∫dvdx/dt which = m∫dv x v because dx/dt = v Therefore W = 1/2mv2, when integrated. However from simple algebra derivation, W = Δ1/2mv2...

Hello, when gas compressed it get heated, proper reasons i don't know. If we consider first kinetic energy increases due to external work done but hows that happens? and if we consider heat is first, where from it came? my guess is that when molecules come closer in confined wall( due to...

Hi there, I'm helping tutor a friend in astrophysics and I've come across a question I can't answer - which is annoying and embarassing to say the least :) The question reads: (a) Calculate the kinetic energy and pressure involved when the Earth gets hit by a stony meteoroid (ρ = 3400...

Homework Statement I want to find the equation of the kinetic energy of a pendulum at any point. I know the initial angle it is released from but I am having trouble finding the velocity at any point to be able to find the kinetic energy at any point. Homework Equations θ =...

A man is running and chemical energy converts to thermal and kinetic. The output (thermal and kinetic ) has the same amount of energy as the input (chemical). But what does thermal and kinetic energy convert to?

Can you explain me this: Ferromagnet has permanent magnetic force and can't lose it in the constant conditions, so if i put magnet and piece of the metal it will be pulled away from the magnet creating some kinetic energy. As energy can't be created, just transfered, so I don't understand who...

When water is vigorously shaken the kinetic energy and, hence, the motion of the molecules increase. Which particular forms of energy do increase : the translational energy (is this the energy associated with the collision and the chaotic random motion of the water molecules ?) or also the...

There is this equation: E=h*f that give us the energy of each photon. If we want to find kinetic or dynamic energy,what equation we will use? Something like K=1/2*m*v^2 (where v is the speed and we have v=A*cos(t/T- x/λ)) ?

Homework Statement A 50 gram steel ball moving on a frictionless horizontal surface at 2.0m.s^-1 hits a stationary 20 gram ceramic ball. After the collision the ceramic ball moves off at a velocity of 2.5m.s^-1. (i) Calculate the velocity of the steel ball after the collision. (ii) Calculate...

Homework Statement (The picture is not from my textbook) A Faraday Dynamo is used as a brake. The brushes are connected with an external resistance R_\Omega. The circular disk has mass m, and angular velocity \omega_0 when t = 0. a) How long does it take until the kinetic energy of the disk...

Homework Statement A solid, Uniform disk of radius 5.00 cm and mass 1.50 kg is rolling without slipping a long a horizontal surface. The disk makes 2.00 revolution per second a. Find the total kinetic energy (translational + rotational) of the disk b. Find the minimum height h of the...

My mcat book says temperature is a measure of the total kinetic energy of a system. Then later on it says temperature is a measurement of the average kinetic energy of a system. Is this an error? Thank you.

I read that based on temperature , electrons have kinetic energy in metals so they randomly move around the ion lattice. when we apply current to a room temperature conductor, the electrons being charge carriers align and form current? but what happens in the plates of a capacitor , when the...

Hi, all. Here is an expression about kinetic energy from analytical dynamics of Haim Baruh which confuses me. "Consider a particle and the case which the kinetic energy is only quadratic in terms of velocity of the particle. We take the differential form of work-energy principle and remove...

So my professor said that the Kinetic energy of the particle in a 3D infinite well is dependent on position where in a 1D infinite well it's NOT dependent on position. She is sort of notorious for being wrong apparently and many of my undergrads are telling me she is wrong. I understand that...

is it related to fermi energy? what is the exact equation form?

Hello folks! I have just come from a night at the pub with fellow students of life where over many a pint several mysteries of the universe were discussed. One of my friends asked me a question concerning special relativity that initially took me by surprise and which has me wondering about the...

This has been bugging me. Several respected propulsion scientists at the 2008 Joint Propulsion Conference claimed that interstellar travel within a human lifetime was impossible. The KE of a rocket traveling at a significant fraction of c would be enormous via KE=0.5 * m * v^2 and that...

Homework Statement A horizontal 845.0 N merry-go-round with a radius of 4.3 m is started from rest by a constant horizontal force of 74.0 N applied tangentially to the merry-go-round. Find the kinetic energy of the merry-go-round after 2.2 s. Assume it is a solid cylinder. The...

Linear Momentum question - help please Homework Statement A 15,000 kg loader traveling east at 20 km/h turns south and travels at 25 km/h. Calculate the change in the loader’s kinetic energy. linear momentum. Homework Equations KE2-KE1 = change in KE p=mv The Attempt at a Solution a...

Homework Statement Blocks A and B are moving toward each other. Block A has a mass of 2.0 kg and a velocity of 50 m/s, while B has a mass of 4.0 kg and a velocity of -25 m/s. They suffer a completely inelastic collision. The kinetic energy dissipated during the collision is: Homework...

Homework Statement At what energy does an electron become “relativistic”? Consider electrons with kinetic energies of 50 eV, 50 keV, and 50 MeV. For each case, calculate the momentum of the electron first using the non-relativistic formula for kinetic energy, and then using the correct...

I read in a science magazine that you would be able to generate more energy by collecting a mass of water and tipping it through a turbine than from generating energy from the impact of that mass of water as individual raindrops. Now this may simply be to do with the technology we have that...

Homework Statement An ice block is being pushed through a displacement d→=(15m)i -(12m)j along an embankment with rushing water. It exerts F→=(210N)i -(150N)J on block. How much work on block does force do? Homework Equations W=Fxd Pythogoreum equation a^2 +b^2= c^2 The Attempt...

Homework Statement A bullet of mass 4.2 g strikes a ballistic pendulum of mass 2.0 kg. The center of mass of the pendulum rises a vertical distance of 18 cm. Assuming that the bullet remains embedded in the pendulum, calculate the bullet's initial speed. Homework Equations The...

Homework Statement If the velocity of a rocket is 10 meters per second and its mass is 10 kg, its kinetic energy is: a. 5000 joules b. 500 joules c. 10000 joules d. 1000 joules [b]2. Homework Equations [/b) Ek= (1/2) mv2 The Attempt at a Solution e=(.5)10x10(2) E=5000 j

If I needed to calculate the kinetic energy of a bar suspended by a rope at one of its ends, in other words, a bar pendulum, do I need to calculate the kinetic energy of the center of mass plus the kinetic energy relatively to the center of mass or do I need to calculate the kinetic energy of...

Homework Statement A 100 kg refrigerator is on rest on the floor.How much work is needed to move the refrigerator at a constant speed for 6 m along with a floor friction force of 200 N ? Homework Equations I used ΔK = W(Fg)+ W (N) + W(f)+ W(T) =0 and W(Fg)+ W (N) = 0 so W(T)=-W(f)=f*...

Homework Statement A 23.0 kg child plays on a swing having support ropes that are 2.10 m long. A friend pulls her back until the ropes are 41.0-degrees from the vertical and releases her from rest. a.)What is the potential energy for the child just as she is released compared with the...

Homework Statement I don't know how to solve this question. 28.8J of work were done in accelerating a mall of 1.8 kg from rest. Find its final velocity. I'm not sure which formula to use..Homework Equations F=ma W=Fs KE=1/2 mv^2The Attempt at a Solution I can't figure out which formula to use...

Homework Statement A ring of mass Mb, radius b, is mounted to a smaller ring of mass Ma, radius a and with the same centre, and they are free to rotate about an axis which points through this centre and is perpendicular to the rings. Dust of mass Ms is distributed uniformly on the inner...

Homework Statement With the work function of copper being 4.65eV calculate the kinetic energy of a photoelectron knocked out with a photon with wavelength of 200nm . Then calculate the velocity of the electron.Homework Equations KE=hf-ø The Attempt at a Solution FIrst time I have done a...

Homework Statement A 5kg ball (m), is to be dropped 1 meter (h) in a vacuum with no resistance in the Earth's gravity (g). Use the speed and motion equations to show that its KE at impact is equivalent to its PE at its starting point. Homework Equations PE = mgh KE= 1/2mv^2...

If an electron is traveling at C/2, the Lorenz formula says that mass is about 1.15 me, do we get the value of KE simply multiplying 1/2mv2 by 1.15? Is it as simple as that?

Homework Statement a rocket explodes in flight into two equal mass pieces still going in the same direction with one piece moving twice as fast as the other. What is the ratio of the total kinetic energy of the pieces just after the explosion to that of the rocket just before? Homework...