Kinetic Definition and 1000 Threads

I tried to use this formula: KE=(1/2)(I)(w)^2, and work=change in KEFor the first question, i tried to plug the number into the rotation kinetic energy formula: 3600rpm=376.8rad/s (0.5)(2,000kg)(0.125m)^2(376.8rad/s)^2 I found out this was the answer 1.1 x 106 J, but I got 2218410J For the...

Homework Statement Problem: A 10 kg box slides down a hill and has a constant velocity. The angle of the hill is 10° with respect to the horizontal. What is the coefficient of kinetic friction between the surface of the hill and the box? Homework Equations Fn = mg + ma ƒk = μk * Fn The Attempt...

A block slides from rest, along a track with an elevated left end, a flat central part, into a relaxed spring, as shown in the figure. The curved portion of the track is frictionless, as well as the first portion of the flat part of L = 10 cm. The coefficient of kinetic friction between the...

1. I have two blocks, one that is 1.6 kg moving left at 3.00 m/s and the other is 2.1 kg moving right at -1.74 m/s, and they are compressing a block with a spring constant of k=600 N/m. I'm supposed to be finding the distance that the spring is compressed at that instant, and I know that...

Hi, I am struggling with a particular point on the derivation of the kinetic theory of gases. Between 5mins and 6mins 30seconds of the video below they discuss how to get a value for the average of the squared velocities of the molecules in the gas. The bit I don't get is why they divide by 'N'...

Homework Statement A crate is pulled by a force (parallel to the incline) up a rough incline. The crate has an initial speed shown in the figure below. The crate is pulled a distance of 9.33 m on the incline by a 150 N force. The acceleration of gravity is 9.8 m/s 2 . What is the change in...

question: I came across a question which said: Derive the equation for kinetic energy of a body of mass m and velocity v. What do they mean? Attempt: I actually just wrote that by work energy theorem diff. in KE = work done so Fx = KE $$ max = m \frac {v²-u²}{2x} x = ½mv² - ½mu² $$ each of...

Homework Statement A cannon at ground level is shooting emergency packets to people stranded on the roof of a flooded building of height H=125 meters. The corner of the building is located a distance D=50 meters from the cannon. It is desired that the incoming packets are flying tangent to the...

Homework Statement [/B] A horizontal force of 50 N is applied to a 2.0 kg trolley, initially at rest, and it moves a distance of 4.0 m along a level, frictionless track. The force then changes to 20 N and acts for an additional distance of 2.0 m. (a) What is the final kinetic energy of the...

Homework Statement A stationary gas has a kinetic energy of 500 J at 30 C. What is its kinetic energy at 60 C? Homework Equations KE = 3/2 RT The Attempt at a Solution I first converted T to Kelvin = 333K. I substituted all the values into find KE but my answer is around 40K, which is not...

Homework Statement A rock is dropped from a distance RE above the surface of the Earth, and is observed to have a kinetic energy of K1, when it hits the ground. An identical rock is dropped from 2RE above the surface and has kinetic energy K2 when it hits the ground. Re is the radius of the...

Homework Statement I know incline is 16 degrees I know distance traveled is 2.85 meters I know Vf is 2.71 meters/second I calculated the meu static and got .287 Homework EquationsThe Attempt at a Solution Tried every thing so lost

Homework Statement "Show that particles hitting a plane boundary have traveled a distance 2λ/3 perpendicular to the plane since their last collision, on average."Homework Equations (Root mean path squared) <x> = 2^(.5)λ λ = ( 2^(.5) * n * sigma )^(-1) ANSWER: The Attempt at a Solution...

K = Ktranslational + Krotational My book says that in order for this equation to be valid the moment of inertia must be taken about an axis through the center of mass. Why is this true?

An Object slides with a consistent velocity down an incline that has a 30 degree angle. I'm trying to find the kinetic friction and the ratio that the mechanical energy is lost on the way down. I think I have already calculated µ with F(friction)= µmgcos(θ)=mgsin(θ) out comes Tan(θ) = µ I...

Homework Statement Helium gas with T1 = 500K and P1 = 0.02MPa in a rigid container with volume V = 1 cm^3. Then Helium goes through a process where atoms with kinetic energies greater than kB*T1, where kB is Boltzmann constant, are instantaneously removed from the container. Atoms remaining...

Homework Statement An Electron (rest mass=9.11*10^-31kg) is accelerated to an energy (mass energy+kinetic energy) of 30*10^6 eV (30 MeV). What is its kinetic energy? Its momentum? Its speed? (Note: 1 eV = 1.602*10^-19 Joules; c=2.998 * 10^8 ms^-1) Homework EquationsThe Attempt at a Solution...

Homework Statement An alpha particle (helium nucleus, charge +2e) starts from rest and travels a distance of 2.5 cm under the influence of a uniform electric field of magnitude 12.5 kV/m. What is the final kinetic energy of the alpha particle? Homework Equations U = 1/2 QV = 1/2 C(V^2) =...

Homework Statement See, I was collecting data for a lab, and now when I look it at, I'm being asked to find the kinetic friction force and the coefficient of friction. What I was given was: the mass of the block: .261 kg gravity: 9.81 m/s2 the acceleration: -7.3125 m/s2 And that's it. If it...

hello! how is it called the mechanism that makes watches self-charged by the movements of the wrist? where can I find more info about this? thanks!

Homework Statement A cat is chasing a mouse in a straight line. The cat's mass, mc, = 5.0kg. The mouse's mass, mm, is 0.035kg. Problem 1. If the kinetic energy of the cat is 100 times the kinetic energy of the mouse can the cat catch the mouse? Problem 2. If the cat and the mouse have the...

The equation for kinetic energy is: k = 1/2*m*v2 This confuses me because this indicates it take more and more energy to accelerate... Lets imagine a rocket in space (assume the mass of the rocket stays the same when accelerating) - the formula suggests it would take more energy (therefore...

Homework Statement A cat is chasing a mouse in a straight line. The cat's mass, mc, = 5.0kg. The mouse's mass, mm, is 0.035kg. Problem 1. If the kinetic energy of the cat is 100 times the kinetic energy of the mouse can the cat catch the mouse? Problem 2. If the cat and the mouse have the...

Homework Statement A skier is sliding down a 20o slope at constant speed, what is the kinetic friction coefficient? Homework Equations E = 1/2 mv2 W = Fd F = ma F = μN = μmg The Attempt at a Solution Attempted to use ma = μmgsin20, which crosses out the masses since mass was not given, but...

Homework Statement 2 cars of equal mass and traveling in opposite directions on a wet and slippery road collide and lock together after impact. Neither car brakes before the collision. The tangled wreck moves off in an easterly direction at 5 m/s immediately after the collision. if one car was...

Homework Statement I am trying to answer the following question: Among the animals that appear in the zoo of the Universe there are black holes and neutron stars. The mass of each of these is often the order of the mass of the Sun. The radius of a neutron star is about 10 km and a certain...

Two astronauts are trying to figure out the mass of Mercury and the mass of Neptune. The astronauts decide to hit a 142 g ball with a bat on each planet and see how far it goes. They know the radius of mercury is 2,440 km and the radius of Neptune is 24,622 km. On mercury one astronaut hits the...

Homework Statement What is the ratio of the average speed of an atom of neon to another atom of neon at twice the temperature but the same pressure? Homework Equations KE = 3/2 RT; v1/v2 = sqrt. m2/sqrt. m1 The Attempt at a Solution I first used KE = 3/2RT and substituted 1 and 2 for T and...

Homework Statement An object with mass of 900 kg Is moving at a speed of 0.85c when it collides with an object at rest with mass of 1400 kgs. Find the speed and mass of the composite object. Homework Equations mc^2/gamma +mc^2/ gamma=Mc^2 The Attempt at a Solution My issue is that I am not...

Homework Statement imagine a planet with half the mass and half the radius of Earth ..with temperature reaching 800K k=1.38×10-23 mass of O₂ = 5.3×10-26 does the planet have O₂ or not? Homework Equations ½mv² = ½kT or ½mv² = kT or ½mv²= 3/2 kT either only vertical or anything other than...

Homework Statement A truck is initially moving at velocity v. The driver presses the brake in order to slow the truck to a stop. The brake applies a constant force F to the truck. The truck rolls a distance x before coming to a stop, and the time it takes to stop is t. 8. Which of the following...

Homework Statement You have been assigned the task of designing a flywheel capable of storing the translational kinetic energy of a 600 kg car traveling at 100 km/hr. The flywheel is to be manufactured out of steel and the maximum rotational speed is 12,000 rpm. a. Assuming that the flywheel is...

Hey guys apparently the answer to this is 491 m/s, but i keep getting 34m/s by using a method whereby i find out the height reached by the block then using kinetic energy to potential energy... doesn't seem to work tho! Please help! A 50.0 g bullet is fired into a stationary 10.0 kg block...

I have a situation where I need to figure how much force it will take to stop an 8,000lb tractormoving at a max speed of 5mph in somewhere around a foot. It will not be an impact stop as there is nothing for it to hit but rather a heavy brake stop. It has been quite some time since I have dealt...

Hello everyone, i was looking for suggestions on the beat book in the topic of kinetic theory, i need a book with deep explanation and covers everything from A to Z. I would appreciate it if someone could post a link for their suggestion on amazon or something. thanks in Advance.

Homework Statement Mass m whirls on a frictionless table, held to a circular motion by a string which passes through a hole in the table. The string is slowly pulled through the hole so that the radius of the circle changes from ##l_1## to ## l_2## Show that the work done in pulling the string...

I was thinking about this: Let's consider a dissociation of some chemical that can run in both directions: AB\rightleftharpoons A^{+}+B^{-} Dissociated form is soluble in a solvent and undissociated form is not - it precipitates. Then the reaction proceeds to the left much faster than to the...

Homework Statement A molecule has a velocity v and speed v. I've worked out (and understand) that the number of molecules in a gas with speeds between v and v+dv and moving at angles between Ө and Ө+dӨ to any chosen axis is: (1/2)nf(v)dvsin(Ө)dӨ The internet verifies this. f(v) is the speed...

"if kinetic energy of system of particles is zero, then linear momentum of that system of particles is zero but the reverse is not true. That is if linear momentum of a system of particles is zero, then the kinetic energy may not be zero" This is what I got from my text. Can you provide me with...

Homework Statement A person attaches a spring to an cubic object that weighs 36kg and pulls this object along a table made of material X horizontally with a steady speed of 1.3m/s. The spring stretches a distance of 3.4cm. Find the ratio of the spring constant to the kinetic friction...

Homework Statement Just found this site ,looks really helpful , so i am doing some revision using past exam papers and have a few head scratches you guys maybe able to help with . A car of mass 1000 kg is traveling at a speed of 25 m/s when it applies its brakes suddenly. The car immediately...

I am confused about the following; where am I going wrong here? 1. (1/2)kT is defined as the average kinetic energy of the molecules of a substance at temperature T, right? 2. You can derive the Boltzmann distribution/Boltzmann factors using (1/2)kT as the kinetic energy, making an argument...

Given psi as function of x^2, and the potential energy as function of x, find the kinetic energy. My reasoning: KE=P^2/2m and use the momentum operator. My professor's reasoning: Calculate the hamiltonian operator and subtract the potential energy then divide by psi. Note: I talked to my...

How was the formula for kinetic energy found, and who found it? My questions mostly concern the history of physics. Who found the formula for kinetic energy ##E_k =\frac{1}{2}mv^{2}## and how was this formula actually discovered? I've recently watched Leonard Susskind's lecture where he proves...

I always thought when there is no force acting on an object it moves at constant speed but every object that moves generates gravitational waves what causes that object to lose energy. Does it mean that object loses kinetic energy and slows down and after some (very long) time will stop.

Homework Statement There is a box that has a mass of 30 kg. The coefficient of the static friction is 0.75. Find the horizontal force. Homework Equations Fs=muFn F=ma The Attempt at a Solution Fs=(.75)(.98)(.30)=.2205 N That is probably way off... I am very confused right now. Could someone...

Could someone explain to me how the kinetic energy of a body moving in a circle is like? I got tempted it stays constant as the speed is constant but that turned out to be false. I am interested in places where the body is at top, side and bottom and so on. So I'd like to also know what the KE...

Homework Statement So a car owner wants to change his current tires and rims to a wider set of tires and rims for increased handling ability. However, the owner does not want to lose any acceleration performance due to the increased friction of having wider tires. To combat this, the owner...

Hi, I'm trying to get the relativistic kinetic energy, ## T ##, from the work expended, ## W ##, (assuming that the body is at rest initially) and I'm doing it like this (in 1D): \begin{equation} W = T = \int F ds = m \int \frac{d(\gamma u)}{dt}u dt = m\int u d(\gamma u) \end{equation} Where...

Homework Statement This is my first thread in this forum, please forgive me if I made any mistake on posting. Homework Equations I am having difficulty on solving the Problem 5. The Attempt at a Solution The answer I obtained is 1.5MeV, is it correct ?