Kinetic Definition and 1000 Threads

Homework Statement This question has two parts; the first part I understand but the second part I do not. Part 1: What is the rotational energy of a planet about its spin axis? Model the planet as a uniform sphere of radius 6420 km, and mass 5.59x10^24 kg. Assume it has a rotational period...

Homework Statement What is the minimum amount of kinetic energy of proton that hits another still proton so reaction ##p+p\rightarrow p+n+\pi ^+## is possible? How big part of the initial kinetic energy is used for kinetic energy of new particles?Homework Equations The Attempt at a Solution...

Hi Everyone, This is a real simple question, but I should make sure I have this right. In the following formula, is the value of P in watts? P = 1/2 Aρv3 I'm assuming that this is in watts, but you know what they say about assuming. Thanks in advance for your help! Cheers, Rick

Homework Statement What is the minimum amount of kinetic energy of electron that hits another electron, so ectra electron-positron pair is produced. Homework Equations ##p^{\mu }=(E/c,\vec{p})## The Attempt at a Solution Before the collision: ##p^{\mu...

A 2-kg block is attached to a horizonal ideal spring with a spring constant of 200 N/m. When the spring has its equilibrium length the block is given a speed of 5 m/s. What is the maximum elongation of the spring? Is not the solution simply: 1/2kx2 = 1/2mv2 x = (mv2/k)0.5 x = 0.5 m...

Homework Statement A uniform solid sphere of mass M and radius R has a light, thin metal spike driven through it, so it is free to turn about this spike. So imagine a bowling ball on a stick that is free to rotate about this stick. A bullet of mass m is fired at speed v into the ball at a...

Homework Statement In a simple model of the wind speed associated with hurricane Emily, we assume there is calm eye 18.8 km in radius. The winds, which extend to a height of 4000 m, begin with a speed of 303.0 km/hr at the eye wall and decrease linearly with radial distance down to 0 km/hr at a...

A hollow, thin-walled sphere (ICM = 2MR2/3) of mass 20 kg is completely filled with a liquid of unknown mass. The sphere is released at the top of a plane inclined at 30° to the horizontal, and it rolls 20 m to the bottom in 3.6 s. What is the mass of the liquid? 2.My approach is...

Homework Statement An 8-kg sphere A is moving to the left with a velocity of 15 m/s when it strikes the 45° inclined surface of a 10-kg block B which is moving to the right a 5 m/s. The ball strikes the block 1 meter above the ground. The block is supported by rollers and impact is perfectly...

What happens if a ball goes from rolling on a surface to a frictionless surface? I know friction is required for the ball to roll, so would the rotational energy be transformed into translational energy (the ball goes faster without rolling), or does something else happen? Thanks!

Homework Statement You are given Force as a function of distance (F vs x). Find the change in kinetic energy from $x=a $ to $x=b$. Homework Equations see attempt solution conservation of energy equations The Attempt at a Solution Since F = -dU/dx we get the integral of F = U...

Homework Statement In reference frame S', two protons, each moving at .500c, approach each other head-on. a) calculate the total kinetic energy of the two protons in frame S'. b) Calculate the total kinetic energy of the protons as seen in the reference frame S, which is moving with one of the...

Homework Statement A solid cylinder is rolling without slipping. What fraction of its kinetic energy is linear? Homework Equations Ke=\frac{mv^2}{2}+\frac{I(v/r)^2}{2} The Attempt at a SolutionKe=\frac{mv^2}{2}+\frac{(v/r)^2}{2}*\frac{(mr)^2}{2} Ke=\frac{3(mv)^2}{4} Linear Ke...

Can anyone explain this case ? If a moving box is pulling with a force F and the kinetic friction is 0.4F, of course, it will move in the direction of applied force with an acceleration and the net force is 0.6F But what if the force suddenly decreases to 0.3F ? The box is still moving so the...

A box slides down a 30° ramp with an acceleration of 1.20 m/s^2. Determine the coefficient of kinetic friction between the box and the ramp ok so the only equations I know are μk= Fk(kinetic friction)/Fn(normal) and that Fn=mass x gravity so i don't know how to get Fk or mass... so help on...

How can you tell the difference between kinetic energy and momentum? I know KE is a scalar and momentum is a vector but physically how do they differ? I don't seem to have a full intuitive understanding. I think I do, but I am unsure. I understand the difference quantitatively, KE= (1/2)mv^{2}...

Okay, so I'm at conundrum with my physics textbook and I cannot seem to understand a few concepts. Allow me to elaborate. 1. Why is the total momentum of a firecracker sliding on ice the same before and after it explodes? Shouldn't the explosion cause the momentum to increase since the...

Homework Statement An electric motor is used to pull a 125kg box across a floor using a long cable. The tension in the cable is 350N and the box accelerates at 1.2 m/s/s [fwd] for 5.0s. The cable breaks and the box slows down and stops a )Calculate the coefficient of kinetic friction...

Homework Statement (NOTE: I solved the first two parts of this problem, but I included it anyway so you have background knowledge for the third question) The average kinetic energy of an electron in a ground-state helium atom is 2.4x10^3 kJ/mol. A. What is the corresponding electron...

Homework Statement There's no specific problem statement but I have to explain how I would find out the coefficient of kinetic friction given the angle (θ) of the inclined plane and mass of the object sliding down, nothing else. Homework Equations ƩF = ma μk = Fk (kinetic friction) / Fn...

Homework Statement An unstable particle of mass M = m1 + m2 decays into two particles of masses m1 and m2, releasing an amount of energy Q. Determine the kinetic energies of the two particles in the CM frame. Given that m1/m2 = 4, Q = 1 MeV, and that the unstable particle is moving in...

Homework Statement A block is pushed across a horizontal surface with a coefficient of kinetic friction of 0.15 by applying a 150 N horizontal force. The block accelerates at 2.53 m/s^2. Find the mass of the block. Homework Equations ƩF = ma The Attempt at a Solution μk = 0.15...

Say you're given a function that represents the kinetic energy of some object, what would you have to do to derive the force from that function? I know that for motion along a straight line a conservative force F(x) is the negative derivative of its associated potential energy function U, but...

Say you're given a function that represents the kinetic energy of some object, what would you have to do to derive the force from that function? I know that for motion along a straight line a conservative force F(x) is the negative derivative of its associated potential energy function U, but...

Hello, Please i have a question about the internal energy: The Internal Kinetic energy is the motion of molecules and it's a random motion. But at macroscopic level the whole object formed by those molecules move in a same direction? how it can be? In a flowing fluid not static? thank you

Hey guys, I am in a teaching assistant in another 8th grade science class for my 2nd field experience in a title 1 school. The teacher is really struggling(*) to explain to the students the difference between Mechanical and Kinetic Energy. The book their using defines Mechanical Energy as...

Homework Statement A block is projected up an inclined plane that makes an angle θ to the horizontal. It returns to its initial position with half its initial speed. What is the coefficient of kinetic friction between the block and the plane in terms of the angle of the incline...

Homework Statement Charged particles such as protons are accelerated to high velocities and are allowed to collide with atomic nuclei to probe their internal structure. The electric potential outside of a point charge Ze. A) A lead nucleus (Z - 82) is approximately described as a sphere of...

Hi friends, I have an issue in solving a Kinetic energy problem during collision. Please Help me in solving this. Thank you all in advance. The problem is as: https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-prn2/1375160_1432382953655477_313625437_n.jpg Attempt...

Homework Statement Two closed containers A and B contain equal number of moles of ideal gases GD (diatomic)and GM (Monoatomic) ,respectively. Q .1 a) If the temperature of gases are same,which of them has more average translational kinetic energy ? b) Which of them has more...

Hi All, I have a very simple question on a calculation, I would not doubt it correctness if it were not for the fact I am told by a colleague it is wrong, and I cannot see why (good job college times are gone). We have a cylinder of length L, density $$\rho$$ constant along the cylinder, one...

Homework Statement Two iceboats hold a race on a frictionless horizontal lake. The two iceboats have masses m and 2m. Each iceboats has an identical sail, so the wind exerts the same constant force F on each boat. The two ice boats start from rest and cross the finish line a distance s away...

K'sys=1/2MtotalVcm2+1/2\muVreli2 I understand this equation represents the total kinetic energy in a reference frame. What I'm not getting out of this is the overall concept. I understand that the first part of the equation is supposed to represent the total kinetic energy required to...

What are my units when finding % diff. In kinetic energy? Homework Statement Phrank (36.4kg) runs at 2.2 m/s and jumps onto a large stationary skateboard (2.3kg) on which Phrancine (22.7kg) is sitting. After the collision, Phrank, Phrancine, and the skateboard move at 1.3 m/s. Find the...

Homework Statement Homework Equations The Attempt at a Solution KEi + PEi = KEf 2.4 x 10-19 + e(1) = KEf KEf = 4.002 x 10-19 J So option c would be correct, right? Thank you in advance.

The problem asks to show that the kinetic energy operator is Hermitian. The operator is given as T= -h^2/2mΔ but I know I can also write it as p^2/2m which would be (- ih∇)(-ih∇). My main question is if I can prove this in 1-D so that T=(-h^2/2m)d^2/dx^2 does that generalize to...

E is finite and V is infinite, So T should be negative infinite

A hockey puck on a frozen pond with an initial speed of 12.3 m/s stops after sliding a distance of 198.9 m. Calculate the average value of the coefficient of kinetic friction between the puck and the ice. So I started with finding the acceleration. I divided 12.3m/s by 198.9m then took the...

"A driver makes and emergency stop and locks up the brakes of the car, which skids to a stop on dry concrete. Consider the effect of rain on this scenario. If the coefficients of kinetic friction for rubber on dry and wet concrete are μk (dry)=0.80 and μk(wet)=0.50, how much farther would the...

[URGENT! Stopping Potential~~~~~~~#######~~~~~~~~~~~~~~~~ Homework Statement max Kinetic_energy= e*Vs=hf-work_function Vs is the stopping potential The attempt at a solution I am wondering, does this stopping potential refers the voltage difference of V_Emitter (where the...

Homework Statement A 4.5 kg block is on an incline with a coefficient of static friction of 0.50. The angle that the ramp makes with the horizontal is increased gradually, until the block begins to slide down the ramp. If you know that the coefficient of kinetic friction between the block and...

Hello everyone, I've run across an interesting Newtonian physics problem that I'd like some input on. The problem begins with a rotating object. Let's assume it is a slender rod rotating about one end with a given mass (m), length (L) and rotational speed (ω). This results in the rod having...

Homework Statement A container having a volume of 1m^3 holds 5 moles of helium gas at 50C. If the helium behaves like an ideal gas, the rms translational kinetic energy is? Homework Equations Total E= 3/2 nRTThe Attempt at a Solution I tried solving this question using this equation, but I did...

Hi, If I have a body which is freely vibrating with kinetic energy given by, say, Ekin=(1-1/10sin(ωt))cos2(ωt) what can be said about the potential energy? Of course the total energy should be constant but how big is it, in other words what is the potential energy? Thanks!

Homework Statement What is the maximum possible kinetic energy (keV) of a Compton electron and the corresponding minimum energy of a scattered photon resulting from scattering of a) 100 keV photon b) 1 MeV photon Homework Equations Δλ = 0.24(1-cosθ) The Attempt at a...

I have found that the kinetic energy term for each mass on a coupled (by a spring) pendulum has no \dot{y} terms, as in the the masses do not move in the y direction at all. What am I missing here? I know they are connected, but in the first normal mode, both masses should move like regular...

Hi, I'm learning about momentum and kinetic energy and I wanted to know if the following relationships are true. I think they are true, but I am not sure: If kinetic energy goes down and mass stays constant, momentum goes down If kinetic energy stays constant and mass goes down, momentum...

I really don't understand this example: A feather or spring or whatever it's called got the stiffness 29.5 N/m. It is lying inside a horizontal tube (feather cannon). The feather /spring is connected in the very end of the tube. The feather / pring is as "long" as the tube if it's not being...

Are there any fans of truck or tractor pulls out there? I am trying to understand what is happening to the coefficient of friction as the sled transitions from kinetic friction back to static friction. It is a fairly complicated model... The weight imposed on the front plate of the drag...

How could you tell in an experiment which was happening?