Consider a bound two-body system ($M>>m$) such as Earth–Moon. I'm trying to understand whether there's a meaningful asymmetry in how identical dissipation processes affect gravitational entropy ...

When a wheel rolls without slipping, friction acts backward at the point of contact with the ground. However, the torque due to that friction seems to be in the same direction as the wheel’s rotation....

So, I took an exam yesterday and it asked, "Rubbing hands ___ internal energy" and it gave the options: Increases, Decreases, Does not affect.My though process was that the two hands exert ...

The Liouville equation is valid for a conservative system where the Jacobian equal one. So, the volume of the ensemble in the classical phase space in canonical coordinates (q,p) does not change. In ...

Road loss of a bicycle tire is usually explained as the work of deformation, as the leading edge continually deforms upon contact with the pavement; i.e. the tire flattens. However, at the trailing ...

Whenever there is a dissipative, or more generally, a non-conservative force, one that can't be derived from a potential in the form $$Q_{\text{pot}}=\frac{\mathrm{d}}{\mathrm{d}t}\Big(\frac{\partial ...

My question is that why do we use the words potential and potential difference in circuits when they are used to calculate work done when there is no acceleration of charges but electrons in a circuit ...

In Chap.I of the book, Electrodynamics of Continuous Media by Landau, Lifshitz and Pitaevskii, they write,Let us begin by studying the static electric fields produced by charged conductors, that is, ...

The time evolution operator can be written in this way, where $u_k(j)$ are the time dependent amplitudes.$$U_j = \exp\left\{ -i \Delta t \left( {H}_0 + \sum_{k=1}^{m} u_k(j) H_k \right) \right\}.$$...

Consider the following trajectory$$\dot{x}(t) = 1-\frac{x(t)^2}{x^2_0}.$$The solution to the above is as follows$$x(t) = x_0\coth\left[x_0t+\coth^{-1}\left(\frac{x_i}{x_0}\right)\right] \quad x >...

I often read and hear from physicists that perpetual motion isn't possible due to the second law of thermodynamics. However, this doesn't make sense to me. The law doesn't say that the entropy of an ...

Wikipedia gives the following formula for the time scale over which an orbiting body becomes tidally locked:$$t_\text{lock} = \frac{\omega a^6 I Q}{3 G m_p^2 k_2 R^5}.$$The article defines each ...

Hypothetically speaking, if one had a hollow sphere that had a perfectly polished mirrored interior surface with little to no light absorption, and then sought to fill the interior space by ...

The Caldeira-Leggett model for a one-dimensional system with coordinate $X$ and momentum $P$ is given by the Hamiltonian$$\frac{P^2}{2m} + V(X) + \sum_i \frac 1 2 p_i^2 + \frac 1 2 \omega_i^2 \left(...

There are two bodies, Body "A" and Body "B". Both have the same mass but different stiffness. If both bodies have same heat energy or the same energy but differ in stiffness, it ...