Kinetic Definition and 1000 Threads

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)

This came up whilst helping my kid with her GCSE physics so ought to be pretty straightforward. Here goes: At his level the kinetic theory of matter is taught in a simple way and one "key point" which is stated time and time again is "the particles in a gas have more energy than the particles...

Homework Statement A horizontal force of 150 N is used to push a 50.0 kg packing crate a distance of 5.00 m on a rough horizontal surface. The acceleration of gravity is 9.81 m/s2 . If the crate moves with constant velocity, calculate: a) the work done by the force. Answer in units of J. b)...

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 =...

Can you help me work something out, please? I'm writing a science fiction story, and want to work out how much impact energy would be produced by railgun. As a starting point, though I'm sure it should be way too high, if I accelerated a 300kg shell to 290,000 m/s, the kinetic energy should be...

Homework Statement A lab I've performed was measured using forces. As the mass increases, the force does as well. The inclined plane is at an angle of 30 degrees. Now, finding the coefficient, should the kinetic and static friction be decreasing on a plane? I've measured the frictions on a flat...

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...

Hi! I'm pretty sure someone would have already made this if it did work, but I don't know why it wouldn't. Can someone explain why this spacecraft couldn't move forward?

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 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...

Homework Statement While traveling on the highway with your 1000kg car, at 115.2 km/h, where you’re ABS (automatic braking system) is disabled. This means braking is relying solely on the friction of your tires with the road when they stop spinning. A dear jumps into the road 50 meters in...

Homework Statement A 4.30 kg block is pushed along a floor by a constant applied force that is horizontal and has a magnitude of 43.0 N. The figure gives the block's speed v versus time t as the block moves along an x axis on the floor. The scale of the figure's vertical axis is set by vs =...

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...

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...

Hi all, I'm brushing up on some thermodynamics, and having been reading up on the interpretation of temperature as derived from kinetic theory. I can follow the derivation for an ideal, monatomic gas which relates temperature to the average, translational kinetic energy of the molecules. Most...

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 crate on a rough horizontal floor is being moved horizontally by a force applied at a 16 degree angle above the horizontal. This is the smallest force that will move the crate at constant speed. What is the coefficient of kinetic friction? A : .11B : .27 C ...

Hi all, I'm trying to come up with velocity equations for a multi-enzymatic system and came across this velocity equation. Does anyone recognize this equation? There was no citation or derivation and the variables were not explained. This is my guess: P, Q, A, B are concentrations of some...

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...

All particle species are in equilibrium at early times of the universe. But I didn't find any book that makes the difference of kinetic and chemical equilibrium clear. I have some of my own opinions and I hope to get your comments: (1) kinetic equilibrium means the distribution function obeys...

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 I'm stuck on question A4 that is linked below. University won't provide me with any solutions. I have a TKP resit exam next month. Homework Equations dU=dQ-PdV The Attempt at a Solution Internal energy is equal to heat flow plus the work done. Work done is 0 because it's...

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...

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".

Homework Statement This is a theoretical question from my homework. We did a lab in class where we were using motion to see how kinetic friction is affected by different variables. We found the acceleration of a sliding wooden block (sliding on another wooded block), and then used that...

Homework Statement A marble that is rolling without slipping approaches a hill at 8.5 m/s. How high vertically will the marble go under these circumstances: If the hill is rough enough to prevent any slipping? If the hill is perfectly smooth? Why does the marble rise to different heights when...

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

Homework Statement The question is to specify all forces and constraints that are applied in a system of a two-seat merry go round model in terms of the generalised coordinates - and their type (e.g. geometric, kinetic). http://i.imgur.com/FQ7PJyg.png The system is modeled as central...

Hi, I have been working on this problem for a while: You place a book flat on a table and press down on it with your right hand. The hand-to-book and table-to-book coefficients of kinetic friction are 0.48 and 0.43 respectively. The book's mass is 1.14 kg and your downward push on it is 9.70 N...

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...

Homework Statement Given a 2.0 kg mass at rest on a horizontal surface at point zero. For 30.0 m, a constant horizontal force of 6 N is applied to the mass. For the first 15 m, the surface is frictionless. For the second 15 m, there is friction between the surface and the mass. The 6 N force...

Homework Statement The sports car ) is rounding a flat, unbanked curve with radius R . If the coefficient of static friction between tires and road is Us, what is the maximum speedat which the driver can take the curve without sliding? why in this problem i am given Static fiction coefficient...

Homework Statement A body is moving on a horizontal plane which gradually turns to another plane forming an angle ##α##. Friction coefficient is ##μ##. Find the kinetic energy of the body after the turn if in the beginning it was ##K_o##. Homework Equations Newton's laws. The Attempt at a...

Homework Statement Homework Equations Please see below. The Attempt at a Solution I'm pretty sure my method is correct but I'm getting small answers: $$ COM \\ \\ E_{6}= E_{2}+E_{\alpha} \\ \\ Minus \ E_{2} \ and \ square \ both\ sides\\ \\ E_{6}^{2}+E_{2}^{2}-2E_{2}E_{6}=E_{\alpha}^{2}\\...