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.
Homework Statement
So first the task:
Determine the average value of the kinetic energy of the particles of an ideal gas at 0.0 C and at 100 C (b) What is the kinetic energy per mole of an Ideal gas at these temperatures.
I took the above right out of the pdf we got from our professor.
I know...
Homework Statement
A truck is moving at constant velocity v0 with a box of mass m on it. Suddenly it starts decelerating until its velocity becomes zero. Between the box and the truck the is a force of friction and the deceleration of the truck is sufficiently slow to allow the box not to start...
I am having trouble deciding when to use which equation.
If you're given the wavelength of a proton, let's say 100 fm, and have to find the kinetic energy of it, how would you do this?
Here are my ideas:
Idea 1: Use lambda = h/p, where p = sqrt(2Em).
Idea 2: Use E=(pc)^2+(mc^2)^2 =...
Homework Statement
Homework Equations
Q = c m ΔT
The Attempt at a Solution
so converting 55 mph to meters per sec gives me a velocity of 24.58 m/s
kinetic energy of car is 1/2 m v2
i set 1/2 m v2 = c m ΔT
plugging in v and c and masses of both
ΔT = 134.56
is that correct?
Homework Statement
A bullet of mass 2.0 * 10-3 kg is fired horizontally into a free-standing block of wood of mass 4.98 * 10-1 kg, which it knocks forward with an initial speed of 1.2 m s-1.
(a) Estimate the speed of the bullet.
(b) How much kinetic energy is lost in the impact?
(c) What...
Homework Statement
The problem is that my teacher asked to solve this using kinetic energy but i doubt it uses kinetic energy... i thought it uses potential energy.
[/B]
You put your little sister (mass m) on a swing whose chains have length L and pull slowly back until the swing makes an...
Homework Statement
The kinetic energy (in keV) of the alpha particle, when the nucleus 84210Po at rest undergoes alpha decay, is
A 5319
B 5422
C 5707
D 5818
Homework Equations
## E = mc^2 ##
Kinetic energy ## = mv^2/2 ##
The Attempt at a Solution
alpha particle is emission of helium nucleus...
Homework Statement
After being hit, a 0.145 kg baseball has a speed of 45.6 m/s.
1. What is the kinetic energy of the baseball after it has been hit?
2. How much work is done on the baseball by the baseball bat?
3. In moving through the air, the baseball slows down to a speed of 30.0 m/s...
Homework Statement
A particle charge of 7.6μC is in a uniform electric field directred to the left. Another force, in addition to the electric force, acts on the particle so that when it is released from rest it moves to the right. After it has moved 8cm, the additional force has done...
As we know that every object that has kinetic energy could also have potential energy. Now suppose an object is in rest at a distance of h meter from ground so it has some potential energy and no kinetic energy, now if it starts to fall towards the ground can we say that its total potential...
I am curious about how a particle's kinetic energy changes with the explansion of the unverse. I calculated that for a matter dominated universe it would vary as 1/a2, while the photon temperature varies as 1/a. Is this correct? Is this also true in general? If so, the implication would be...
In case of quantum LHO in eigen state of the system ##|n \rangle##
\langle \hat{T} \rangle=\langle \hat{U} \rangle=\frac{1}{2}(n+\frac{1}{2})\hbar \omega
What will happened in some superposition of states? Does Ehrenfest theorem can tell me something more general? Is it possible to say that...
I was wondering why the average kinetic energy is calculated in this manner.
They are dividing the kinetic energy function by the period (noted here as To) and integrating it with limits from 0→To. Why?
(This is a tiny portion of a larger textbook example, not an actual assignment.)
Sorry for...
Hi, here i need to calculate the tilt angle of the scissor lift. I had done some reviews for designing a scissor lifter, some source state that, tip-over will happen only when the kinetic energy of the system is less than the Potential energy after impact.
Hence, i was trying to use this...
I have performed an experiment testing how mechanical energy is conserved. I conducted this experiment by first creating a ramp. I gathered data by first calculating the gravitational potential energy of a marble on various points on the ramp (depending on height). Next I rolled the ball down...
Has anyone ever seen KE derived this way? The only non-classical assumption is that mass = Energy/c^2 (I know, that's a big one) and that it accumulates as mass as the object is accelerated. (sorry for the plain text formatting, I need to learn how to do it right, I may reply with my first try)...
1. The temperature of air wil ... if we add a hydrogen molecule of a speed higher than 1980 m s/-1.
2. The temperature of air will ... if we take away a hydrogen molecule of a speed highr than 1980 m s /-1.
3. The temperature of air will ... if we take away a hydrogen molecule of a speed lower...
Imagine this object as a big tanker ship, moving to the right
weight 500 000 metric tones
linear velocity 0.01 m/s
momentum cca 5 000 000 kg m/s
kinetic energy 25 000 J, which is 25 kilowatt-secondshow much power could i extract from this object in order to slow it down to complete stop ...
Lets think we have a sphere and it moves a constant veloctity v.So it will have a kinetic energy.Is this kinetic energy efectts spheres particle energy.(sphere made up but atoms)
Thanks
Hi fellow scientists and engineers,
I have a question regarding the design of a flywheel. I know that the actual engineering of a flywheel is very complex and in no way I should expect actual practical answers from this simple question. I'm just trying to get some estimates for a renewable...
What equations can be used to compare the force of a resting X mass to the force of a smaller Y mass falling Z distance.
Specifically, how much resting mass would equal the force of 300 pounds being dropped from 10 feet up?
Homework Statement
There is a system consists of a ball and the earth. Explain why you can consider the kinetic energy of the system equals to the kinetic energy of the ball.
Homework Equations
##F=-\frac{m_{1}m_{2}}{{r}^{2}}##
The Attempt at a Solution
The magnitude of the force acting on...
Why is the average kinetic energy of the molecules a cold liquid less?
As the temperature of a liquid decreases, the average kinetic energy of its molecules reduce. What is the reason behind this?
Homework Statement
If I have a ball moving in a circular path (ball is connected to a string), as shown in this picture:
http://w3.shorecrest.org/~Lisa_Peck/Physics/syllabus/mechanics/circularmotion/Images/cent_force_on_ball.gif
should I say that the energy of the ball is both its kinetic...
Homework Statement
A car has a power output of 45kW and travels at a constant speed of 30m/s. What force is the engine applying on the car?
Homework Equations
F=m*a
W=ΔKE+ΔGPE
KE=½mv^2
GPE=mgh
W=F*d
P=ΔE/ΔT
gh_1+½v_1^2=gh_2+½v_2^2
The Attempt at a Solution
I really have no clue. Since there...
Homework Statement
Find the speed parameter β and Lorentz factor γ for an electron that has a kinetic energy of:
a) 6.00 keV
b) 2.00 MeV
c) 4.00 GeV
Homework Equations
KE=(γ-1)*511 KeV
SQRT(1/(1-β^2))=γ
The Attempt at a Solution
a) 6 KeV=(y-1)*511
y=1.0117
1.0117=SQRT(1/(1-β^2))
β=0.152
b)...
Hi, I'm just an average guy here, mostly self educated, and am looking for experts to verify my theories on developing revolutionary impact protection. If I disrupt direct impact to the head using a highly elastic layer of material, does that create an inelastic impact interruption? A helmet...
In the included picture, I don't get how they get to the kinetic energy part. I would say, that the traveled distance is equal to (l + x(t))*θ. Then I would take the time derivative, resulting in dx(t)/dt * θ + (l + x(t))* dθ/dt. Then I would square this result and multiply that with 1/2 m. But...
Hello!
I've read that electrons can only absorb photons of exactly the right amount of energy to move to a higher energy level, if its to little or too much then it doesn't absorb it at all, so my question:
How can electrons be liberated from an atom with Kinetic energy when they can't absorb...
The question is about 2 sticks standing above each other, but i have a more general question.
The position of my mass is described by: (2rsin(a) - rsin(b) , 2rcos(a)+rcos(b))
the goal is to get a formula for the kinetic energy, so i need the speed of the mass.
If i take the derivatives of...
Kinetic Energy of Double Compound Pendulum and Parallel Axis Theorem
Hello, there.
I have a project I'm working on where I need to be able to calculate the kinetic energy of what basically amounts a double compound pendulum. However, the pivot point of the second pendulum is not at the center...
I think its correct to state that:
"Kinetic energy is a property of a moving object."
But would it be correct to state that:
"Kinetic energy is carried by a moving object"? If not is there a better alternative terminology to use?
Thank you.
Homework Statement
I was given a chart to figure out the different momentum and kinetic energies of different collisions (elastic and inelastic) and in the lab he posed the question "Calculate the percent elasticity for each of the collisions."
Homework Equations
conservation of momentum...
The question is.
There are two particles, one with charge -q and the other with charge Q, and -q particle rotates around the Q particle at a radius r1. What is the Energy at this point?
The answer is like this: E= KE + U
So now I know that U= -kQq/r1
But according to the answer: KE= kQq/2r1...
Homework Statement
A 6.0-kg object, initially at rest in free space, “explodes” into three segments of equal mass. Two of these segments are observed to be moving with equal speeds of 20 m/s with an angle of 60° between their directions of motion. How much kinetic energy is released in this...
Homework Statement
A pion at rest (mπ = 273me) decays into a muon (mμ = 207me) and an antineutrino (mn ≈ 0).
Find (a) the kinetic energy of the muon and (b) the energy of the antineutrino in electron volts.
Homework Equations
K = (γ-1)mc2
E = γmc2
ER = mc2
E2 = p2c2 + (mc2)2
I didn't...
Homework Statement
[/B]
Objects A and B, of mass M and 2M respectively, are each pushed a distance d straight up an inclined plane by a force F parallel to the plane. The coefficient of kinetic friction between each mass and the plane has the same value...
Question: A streetcar is freely coasting (no friction) around a large circular track. It is then switched to a small circular track. When coasting on the smaller circle its speed is:
a) greater
b) less
c) unchanged
Relevant
Formulas:
w = v/r
KE = 1/2mv2
My teacher said the normal force from...
If an object is dropped from height, h, then gravitational energy is E = mgh, but kinetic energy when object hits the ground is E=(1/2)mv^2. Conservation of energy states that E(g)=E(k). Why does kinetic energy not depend on height object was dropped?
Homework Statement
Homework Equations
1/2 mv^2 = mgh
The Attempt at a Solution
first, a side question, if p = mv, can't we just place p into 1/2 mv^2 so it becomes 1/2 p^2?
anyway, on to the question, at the point where the cube falls off, the Fnormal should just about equal 0, correct?
is...
Homework Statement
Prove kinetic energy is relationship between mass and velocity using E(g)=mgh (no calculus, momentum, kinematics).
Homework Equations
gravitational energy: E=mgh
kinetic energy: E=(1/2)mv^2
The Attempt at a Solution
I know it can be derived using the gravitational energy...
Homework Statement
A crate of mass 9.2 kg is pulled up a rough incline with an initial speed of 1.52 m/s. The pulling force is 110 N parallel to the incline, which makes an angle of 20.6° with the horizontal. The coefficient of kinetic friction is 0.400, and the crate is pulled 4.94 m.
(e)...
Homework Statement
So the first part asks to prove the time derivative of kinetic energy is dT/dt=F dot product v which I did not problem. but then the second part of the problem asks to prove that if the mass is changing with time then the time derivative of d(mT)/dt=F dot product m and I'm...
In class we had a conceptual problem:
There will be a race between two springs. Both will receive the same initial impulse, but one has been agitated and is therefore oscillating in some way, the other is just still. Who arrives first?
The answer is that the still spring arrives first because...
Homework Statement
Imagine that you have been given the job of desiging a new bungee jumping platform. Customers of mass 53.0 kg will step off a platform, attached to a rope of unstretched length 52.6 m and spring constant 17.0 n/m.
How far below the platform will the end of end of the rope...
Hi all,
Does electromagnetic radiation actually carry kinetic energy?
Looking around the web gives different answers. I have seen explanations like radiation pressure experiments as evidence, but this has been argued being effects from energy absorbed by the recipient.
In case it does not...
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...
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...