In physics, the kinetic energy of an object is the energy that it possesses due to its motion.
It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes. The same amount of work is done by the body when decelerating from its current speed to a state of rest.
In classical mechanics, the kinetic energy of a non-rotating object of mass m traveling at a speed v is
1
2
m
v
2
{\displaystyle {\begin{smallmatrix}{\frac {1}{2}}mv^{2}\end{smallmatrix}}}
. In relativistic mechanics, this is a good approximation only when v is much less than the speed of light.
The standard unit of kinetic energy is the joule, while the English unit of kinetic energy is the foot-pound.
I first tried to get the solution by conserving the rotational kinetic energy and got ##\omega'=\frac2{\sqrt5} \omega##.
But, it was not the correct answer. Next I tried by conserving the angular momentum and got ##\omega'=\frac 45 \omega##, which is the correct answer.
Why is the rotational...
If we have a photon being converted to a positron-electron pair, but we lack enough energy for this to happen (hv<2Me*c^2) but the difference is smaller than the uncertainty amount, such that tunneling may be possible, would the resultant pair have net negative energy? Would tunneling even be...
Hi all,
I've read so many times that "temperature is a measure of the average kinetic energy of the molecules in a substance," or sometimes "particles" to encompass atoms and ions too. But how big can "molecules/particles" be before their kinetic energy is no longer relevant to temperature?
If...
I am not sure I understand the question. I imagine there is a horizontal table and all the diagrams are the top-view of the table.
The question states that "A particle moves from P1 to P2 without acceleration along five different paths". In the first picture, I think the path is in the shape of...
If this question asked for internal energy, then it is a straightforward thing, just use the formula U = (3/2) nRT = (3/2) PV. But the question specifically asked for average translational kinetic energy which I'm stuck with the value of T to plug in into the formula as the question only give us...
I've marked the right answers.
They mainly indicate at power carried by the particles being zero, and here is my doubt- why should it be zero? Shouldn't it have some definite value?
I do understand that the kinetic energy is max at the y=0 and potential energy is max at y=A, but I don't know...
When does an object have rotational energy? Is it only if it rotates around an axis within the object? Does for example a ball attached to a string with a uniform circular movement have rotational kinetic energy?
I'm trying to make up an example for my students to illustrate that in nuclear decay, mass-energy and momentum are both conserved.
I found this problem: https://physics.stackexchange.com/questions/304277/calculate-velocity-of-radon-220-nuclear-after-decay
I am trying to modify it so that they...
How did you find PF?: We can derive the equation 1/2mV2. But what is the fundamental reason behind mV2(total energy) is divided by half?
I find only derivative solutions to this question. But still unsatisfied.
first, i calculated the kinetic friction:
0.77 x (weight of the 2 boxes x 9.8)= 55.16N
then i calculated the angle of the triangle:
tan^-1(2.5/4.75)=27.758
then i drew this
then i used sine to find out force 3 which is 33.3556
so the final force needed is 33.3556 + kinetic friction=...
Does anybody know of a derivation of the van der Waals equation from the molecular kinetic theory of gases, but without using the tools of statistical physics (such as partition functions)?
I apologize in advance if this is in the wrong forum, I have no idea where this question would really sit.
A number of proposed theoretical weapons, and a concept often used in science fiction, describe a satellite launched, or rather dropped, rod that would gain large amounts of kinetic energy...
Well I am pretty sure that the kinetic energy stays the same because in this case the velocity vector and energy make a ninety degree angle so no work is done, but I am lost about angular momentum. It could decrease maybe if the torque is clockwise while the ship is going in a counterclockwise...
So, I know the right solution should be like it has same potential energy initially, in the trial one, since the floor is frictionless, the plane will move too and it shares the potential energy with the block. So in trial 1 the potential energy equals final kinetic energy of the block and...
Hello! When the kinetic energy of a molecule is written in its CM frame we get the formula attached. The first term is the kinetic energy of the CM frame with respect to the lab frame, the second term is the kinetic energy associated with the distance between the nuclei and the last term is the...
Hello,
When a charged particle is inside a magnetic bottle at the right speed, the particle bounces back and forth and is confined inside the magnetic field.
The magnetic force does not work on the particle hence the particle's kinetic energy remains constant.
That means that the particle may...
Let ##\Theta## be the angle, following the movement of the center of the disk.
In order to find the kinetic energy, we brake the movement of the disk into 2: The translation of the center of mass, and the rotation of the disk around it.
So, the kinetic energy will be given by:
$$T= \frac 1 2...
kinetic friction coefficient=tan(angle)
kinetic friction force= tan(angle)x mass x g(9.8)
by these 2 equations, I calculated kinetic friction equation=39.236N
by f=ma,
f= 24.7kg x 8.5ms-2
=209.95N
so the force required should be 209.95+ 39.236N=249.1863?
Im not sure, are there any other...
Hello.
I need some guidance on how to find the fraction of molecules with KE between K1 and K2 from the Maxwell kinetic energy distribution function.
Here's an link to an earlier post where the speed distribution was integrated, how will I proceed with the kinetic energy distribution...
If a block slides down an inclined surface under the presence of the kinetic friction, does that mean the total energy lost by the block is equal to the work done by the kinetic friction? Thanks in advance.
I want to calculate the kinetic energy distribution amongst let's say nitrogen molecules by using M.K.E.D, but not sure where to start.
I posted a picturefrom my physics book where the formula is shown, there was no example in the book.
As for g(K), is K the same as the kinetic energy formula...
I was going over the rolling disk versus rolling hoop problem, in which the hoop has more Kr due to greater I and therefore smaller Kt and v. I know this can be algebraically proved with two unique expressions for V that don't involve omega. The question in class that came up concerns torque. If...
I have some doubts about ballistic pendulums.
First, we say that if a bullet hits the pendulum, the linear momentum is conserved. But when we consider a rod attached to a pivot at one of its ends instead of a pendulum we say that the linear momentum isn't conserved because the rod can't move...
Consider the situation in the attached photo. The kinetic energy in A is 10 J, in B is 30 J. What is the kinetic energy in C?
Using that the mechanical energy is the sum of potential energy ##(E_p=mgh)## and kinetic energy ##(E_k=\dfrac{mv^2}{2})##, we get that the mechanical energies in...
Hi,
When objects fall in a gravitational field, they convert gravitational potential energy into kinetic energy. Because energy is always conserved:
amount of kinetic energy gained = amount of gravitational potential energy lost.
Now the gravitational energy lost should be equal to the amount...
In these lecture notes about statistical mechanics, page ##10##, we can see the graph below.
It represents the distribution (probability density function) of the kinetic energy ##E## (a random variable) of all the gas particles (i.e., ##E=\sum_{i}^{N} E_{i}##, where ##E_{i}## (also a random...
Hey all,
I was recently searching for kinetic friction coefficients, and I noticed that for a reason which is unknown to me, some materials had not been appointed such coefficient. The specific kinetic friction coefficient that I'm looking for is aluminum on greasy/lubricated cast iron. Any type...
In Kinetic theory of gases, what is the reason behind introducing a new kind of average known as root mean square velocity (##v_{rms}##)?
I read the following: The molecules in a container are in constant random motion. So when we add all the velocity vectors to find the average it cancels out...
Hello, I just have a quick question on deriving the kinetic energy formula using calculus. I understand most of it, I just have a question about one of the steps. here are the steps.
Begin with the Work-Energy Theorem.The work that is done on an object is related to the change in its kinetic...
Homework Statement:: Consider a platform (mass: M) which horizontal surface AB s smoothly joined to vertical surface CD as shown in the figure below. Initially, the platform is fixed in place on a horizontal floor. A small object (mass: m) is placed on AB and given an initial speed of v in the...
Hi to all, I whant to ask a question about theoretical chemistry. Let us consider a cyclic reaction ##\alpha A\rightarrow \beta B\rightarrow \gamma C\rightarrow \alpha A## where ##\alpha,\beta;\gamma## are the stochiometric coefficients and ##A,B,C## chemical molecules ... there are relations...
It says that for Ag atoms, from Kinetic Theory, the velocity vx of an atom of mass M is evaluated by setting
(1/2)M(vx)^2 = 2kT
This is my confusion. What I have studied is that it should be equal to (3/2)kT instead of 2kT.
Summary: Finding the KE of a two proton collision that creates Kaons. Given the rest KE of protons and kaons, what is the minimum KE of one proton that can create the two kaons.
In high-energy physics, new particles can be created by collisions of fast-moving projectile particles with...
My solutions: When ball is launched horizontally, assuming its velocity is entirely in the horizontal dimension, there is no interaction of the ball with the gravitational field, thus no change in GPE, so all of the EPE (elastic potential energy ) of the spring is transferred to KE of the ball...
I got acceleration by dividing force by m then replaced a by dv/dt and then integrated it to get velocity as a fxn of time and hence got kinetic energy but problem is my ans does not match with any option can someone please compare their ans
Firstly I tried defining into an equation to make the whole thing more 'tangible'.
##m_1= Paula's~Weight⋅2 = m_p⋅2##
##m_2= \frac {Dave's~weight}{2} = \frac {m_d}{2}##
Before impact
##E_k1= \frac 1 2 (m_p⋅2)(0^2)##
##E_k1= \frac 1 2 (2m_p)##
##E_k1= m_p ##
After Impact
##E_k2= \frac 1 2...
Hi.
I searched and found no answer to this simple question:
Is the spinning wheel in this videoclip keeping the same rotation (kinetic energy) when flipped upside down and back again?
(if we forget about friction)
I always read that the static friction applies when the object is not moving. If it starts moving then you have kinetic friction.
But suppose the case of a block on conveyor belt. The block is moving, but I was told that that friction was static friction.
Or suppose the Death Wall. I've also...
Suppose object1 with mass m and velocity v has collided with a block. Also, object2 that has identical shape and dimensions with mass m/2 and velocity 2v has collided to that block. Since the momenta of two objects are identical but the kinetic energy of object2 is twice:
Are the forces between...
Summary: I always confuse Binding Energy with Released Energy in such processes. Which one comes from mass defect?
For example in a Deuterium-Tritium fusion two nuclei with lower binding energy converse to He-4 with much higher binding energy (and a neutron). The released energy is 17.6 MeV...
Summary: Integrating the 1 dimensional MB Distribution in terms of translational kinetic energy up to infinity, does not yield ##\frac{1}{2}k_BT## as it should be.
The format for the 3 dimensional Maxwell-Boltzmann Distribution is ##A\cdot e^{-\frac{E}{k_BT}} \cdot g(E)## in which ##A## can be...
I'm programming a game in which I'd like to simulate the real world physics of an attack using primarily medieval style weapons. Think dwarf fortress, but rather than assigning damage numbers we're calculating force or kinetic energy. Getting that much is easy enough since I can find the mass of...
My attempt at the solution...
I only have problem in solving part a)
1) i calculated the spring force actingbon the table block and it is greater than the frictionnand tension force acting in the opposite direction, so by that the block will move in left.
2) now i found that which forces are...
Usually when setting up an energy equation I use the general form, (Initial KE) + (Initial PE) + (Any other work done to the body) = (Final KE) + (Final PE) ...
For this I said the initial GPE and KE are 0, and the work done by the field is GMm/x (derived by integrating a force of -GMm/r^2 from...