Kinetic Definition and 1000 Threads

Homework Statement since the bombarding electron has only 7.0eV ... it's not sufficient for the electron in the ground state to be excited which needs 10.4eV , so no excitation occur. and in my opinion, the bombarding electron should emerge with the same amount of energy ... but the ans given...

A block of mass 10 kg is pulled 5 m upwards along a rough surface at an angle of 20 deg, an external force of 100 N and vi = 1.5 m/s. The coefficient of friction is 0.4. Calculate: 1) The work done by gravity 2) The increase in internal energy between the block and the surface as a result of...

HI, I have been going through dirac's paper on quantized singularities in the electromagnetic field and there he referred to a problem of negative kinetic energy of electron, what does it mean? I am going to make a presentation on magnetic monopole next month so I need an explanatory answer...

Just wondering if apparent weight affects kinetic energy or is it only mass that affects it regardless of apparent weight? for example, a helicopter is falling but is providing a small thrust. say the helicopters mass is 50kg and it provides 100N of thrust upwards therefore, using w=mg, the...

Homework Statement An inclined plane of angle θ = 20.0° has a spring of force constant k = 460 N/m fastened securely at the bottom so that the spring is parallel to the surface as shown in the figure below. A block of mass m = 2.51 kg is placed on the plane at a distance d = 0.324 m from the...

A 250-N force is directed horizontally as shown to push a 29-kg box up an inclined plane at a constant speed. Determine the magnitude of the normal force, FN, and the coefficient of kinetic friction, µk. So, I know I have to find the vertical and parallel forces Vertical: Fn and 250 sin of...

Homework Statement We have an object with much smaller mass than compared to the sun. This object is at rest when released at 1AU from the sun. After a week how far is the mass from the sun. The Attempt at a Solution So I look at the gravitational potential energy and set it equal to...

Homework Statement What is the kinetic energy of an electron with a momentum of 40 GeV/c? The Attempt at a Solution Kinetic energy involves velocity of the particle so my first thought was to write momentum in terms of velocity. p = \frac{mv}{(1-(v/c)^2)^{1/2}} p^2 = \frac{(mv)^2}{(1 -...

Homework Statement Show that 1/2mγv^2 does not give the correct kinetic energy. Homework Equations 1/2mγv^2 γ = 1/(sqrt(1-v^2/(c^2))) The Attempt at a Solution Well, since the classical mechanics version of kinetic energy was the integral of momentum with respect to v, I felt I could...

Homework Statement Two objects of inertias m1 and m2 start from rest and then interact with each other (assume neither is interacting with any other object). What is the ratio of their kinetic energies at any instant? Homework Equations \frac{K_{1}}{K_{2}} = ? The first part of the equation...

Is there a way to transfer kinetic energy between two objects without the objects touching one another?

Net Work = Change in Kinetic Energy. What about potential energy? Homework Statement When we say net work = change in kinetic energy, does that mean that if the height of an object changes (and its initial and final velocity) do not change, then the work done also equals the potential...

Homework Statement There is a hemispherical dome that sits on a horizontal plane. It has a radius of 10m. A 2 kg block sits on top of the dome. Pt. 1: Assuming the coefficient of kinetic friction is 0, at what angle, θ, will it leave the dome? Pt. 2: Assuming that μk is 0.3, what is the...

Please could someone explain the following situation. A truck weighs 4 tonnes and travels at 18m/s. A car on the same road, weighs 1.4 tonnes and is traveling at 35 m/s. The car has more kinetic energy but less momentum. My book says that momentum is how hard it is to stop something which is...

Homework Statement http://puu.sh/bz0km/092f2d8781.png Homework Equations h^2/2ma^2 The Attempt at a Solution I've found the uncertainty of the kinetic energy through many means, and I'm confident that it's .052MeV. The easiest method that gave me this answer was: using...

Homework Statement A motor imposes 5 Nm on a shaft of a 100kg flywheel which is 80cm(diameter) What is the rotational kinetic energy after 10 mins? assuming the flywheel was at rest and the mass moment of inertia of the shaft is negligble. Homework Equations Ig=1/2 * mr^2...

This is not a homework question, just a simple physics question which I decided to ask here. I held off from asking in the other general physics forum because I get accused of asking random questions that are insignificant. I really want to understand these terms and how they are compared in...

For the following system, what is the total KE? I have the following \[ \frac{1}{2}m_1\dot{x}_1^2 + \frac{1}{2}J_1\dot{\theta}_1 + \frac{1}{2}J_0\dot{\theta}_0^2 + \frac{1}{2}m_s\dot{x}_s^2 + \frac{1}{2}J_s\dot{\theta}_s^2 \] \(J\) is the mass moment of inertia.

Homework Statement Hi guys! I have a problem pertaining to the kinetic energy gained by a point charge from interacting with a another point charge. Here's the problem: A point charge of mass m1 and charge q is placed near another point charge with mass m2 and charge Q. Both charges are of...

A 250-N force is directed horizontally as shown to push a 29-kg box up an inclined plane at a constant speed. Determine the magnitude of the normal force, FN, and the coefficient of kinetic friction, µk. FN µk (a) 330 N 0.31 (b) 310 N 0.33 (c) 250 N 0.27 (d) 290 N...

I solved the problem myself immediately before anyone replied.

Beginner and first time poster here so be gentle! First off, I understand the main difference is that one is an energy and one is a vector, but can somebody explain the following - A car of mass 1000 kg is traveling at 30 m/s. KE = 450 kJ Momentum = 30,000 kg m/s The driver brakes the...

I am trying to follow this solution but I can't see how the momentum p is equivalent to the sqrt(T^2+2Tmc^2) I get that T=p^2/2m which yields p=sqrt(2mT) but why is there a T^2 term...??

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

Homework Statement (Pathria 6.11) Considering the loss of translational energy suffered by the molecules of a gas on reflection from a receding wall, derive, for a quasi-static adiabatic expansion of an ideal nonrelativistic gas, the well-known relation ##PV^{\gamma} = \text{const.}## where...

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...

The derivation of the ideal-gas equation included the assumption that the number of molecules is very latge, so that we could compute the average force due to many collisions. However, the ideal-gas equation holds accurately only at low pressures, where the molecules are few and far between...

Homework Statement SolvedHomework EquationsThe Attempt at a Solution Solved

If I have ice, water and vapour at the triple point and they are in equilibrium at a temperature of 273.16. Does this mean that the average kinetic energy of the particles is the same in each state? If so how can the molecules in the water be moving with the same mean squared speed as the...

I have a question about deriving the equation of kinetic theory of ideal gas - PV=1/3 Nmcr2, where N is number of atoms, cr is root mean square of atom speed and m is mass of one atom. In deriving the equation, many textbooks consider the total rate of change of momentum within a certain time...

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...

[SIZE="4"]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...

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...

Hi guys, i have some questions regarding Frictional Force that came up in a book. If the cube moves throgh a distance of 4.0m in 2.0s, find the kinetic friction and coefficient kinetic friction between the cube and the plane. ( coefficient of static friction force Us= 0.466, angle of incline=...

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...

Homework Statement Suppose you want to make a velocity selector that allows undeflected passage for electrons whose kinetic energy is ##5x10^4eV##. The electric field available to you ##2x10^5V/m##. What magnetic field will be needed?Homework Equations ##u=\frac{E}{B}## u is velocity, E is the...

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...

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?

Homework Statement A 3-kg mass is attached to a light string of length 1.5 m to form a pendulum. The mass is given a initial speed of 4 m/s at its lowest position. When the string makes and angle of 30° with the vertical, find (a) the change in potential energy of the mass, and (B) the speed...

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...

Homework Statement A sled and its rider have a mass of 90 kg and a speed of 3 m/s at point A on the frictionless hill of Figure 5.25. At the bottom of the hill, the sled moves onto a rough surface with a coefficient of friction of .6. How far from the base of the hill will the sled move...