Questions tagged [energy-conservation]
The law of conservation of energy, which states that the amount of energy in a system is constant. For questions about Earth's environment, see the climate-science tag instead.
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Intuitively, why is the quantity of kinetic energy conserved in a 1-dimensional elastic collision of rigid bodies?
Two blocks of masses and velocities $(m_1, \textbf{v}_{1,\:i})$ and $(m_2, \textbf{0})$ composed of identical material move towards each other on a frictionless plane in vacuum.
They collide. It is ...
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Why do physicists want to apply the energy conservation law to the entire universe, when it is immune to falsification?
General Relativity (GR) itself is an approximation for space- and time-like phenomena. It does not make philosophical statements about reality and could potentially be replaced in the future. The ...
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Energy conservation as a time translation symmetry [duplicate]
Noether's theorem says that a time translation symmetry gives rise to conservation of energy. However, my classical mechanics professor said in class that it was time reversal symmetry that gives rise ...
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Extra energy by applying torque? [duplicate]
Consider two blocks of same mass m lying horizontally. A bullet is fired at first block at its center of mass vertically upwards. It sticks inside the block and the block goes up to a height of $y$ ...
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Inconsistent result when finding the minimum speed to reach the highest point of a circular road [closed]
A car moves from $A$ to reach the highest point $B$ of a vertical circular road. Find the minum speed of the car at $A$. Ignore all frictions.
Using conservation of energy
\begin{align*}
mgh_A+\tfrac{...
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Energy to produce particles in different frames
I am a fourth year undergraduate student taking a course in Nuclear and Particle physics.
When asked nuclear related questions like "how much energy is produced [in the LAB frame] in the decay $X ...
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Virial Theorem: Application to simplify a PDE
Let
$$\frac{d^2\phi}{dt^2}=-\frac{dV(\phi)}{d\phi}$$
be be a PDE in $\phi(t)$, $V(\phi)$ should be physically thought as a potential. In this answer isclaimed that by means of virial theorem the above ...
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An object moving close to $c$ falling into a black hole
Assume there is an object moving at $0.99999999999........c$ (upto like a thousand 9s) towards the center of a non-rotating black hole in a straight line
Since it can't escape once it falls in where ...
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Hamiltonian under the transformation induced by its own flow
Suppose we have a Hamiltonian $H(q,p)$ that leads to the flow:
$$
\begin{cases}
q=q(Q,P,t) \\[2mm]
p=p(Q,P,t)
\end{cases}
$$
where $P=p(0)$ and $Q=q(0)$ are the initial conditions.
I noticed that ...
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Why is rotational kinetic energy not explicitly considered in the energy analysis of a simple pendulum?
In analyzing a simple pendulum, conservation of mechanical energy typically involves gravitational potential energy and translational kinetic energy. However, I noticed that rotational kinetic energy ...
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Under what conditions will a circuit violate conservation of charge and/or conservation of energy?
Consider the following circuit diagram containing two capacitors and an inductor:
Suppose that $C_1$ is initially charged to some voltage $V_i$ and that $S_1$ is closed at $t=0$. If the switches are ...
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Phase cancellation in beams of light- edited
I am reading Anil Ananthaswamy's book on double-slit interference and I realized that there's something which I thought I understood about this, but actually do not- as follows:
Photons propagate ...
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Examples of physical systems where total energy is conserved but total angular momentum/total linear momentum are not conserved?
I came across this question:
$H=\frac{1}{2}{m_1v_1}^2+\frac{1}{2}{m_2v_2}^2+\frac{C}{(\vec{r_1}-\vec{r_2})^2}\hat{z}.(\vec{r_1} \times\vec{r_2} )$
This is a hamiltonian of a two particle system where ...
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Conservation of energy and Coulomb's law
The Coulomb's law states:
$$F = k \frac{|q_1 q_2|}{r^2}$$
where $k$ depends to the medium between two charges. by replacing that medium with something that has a bigger value of k, the force between ...
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Potential difference across objects revolving around earth
Based off of the concept of motional emf, it seems as if metallic objects revolving around the earth must develop a potential difference across them.
Wouldn't it be possible to exploit this potential ...
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