DO NOT USE THIS TAG just because the question contains a formula!
6
votes
2answers
587 views
Can a force in an explicitly time dependent classical system be conservative?
If I consider equations of motion derived from the pinciple of least action for an explicilty time dependend Lagrangian
$$\delta S[L[q(\text{t}),q'(\text{t}),{\bf t}]]=0,$$
under what ...
5
votes
4answers
518 views
Does the stress-energy tensor contain the equations of motion?
Derivatives $\nabla_i T^{ik}=0$ of a stress-energy tensor of physical system express conservation laws. Whether contains a stress-energy tensor also the information on the equations of motion of ...
5
votes
3answers
464 views
What is the relationship between Schrödinger equation and Boltzmann equation?
The Schrödinger equation in its variants for many particle systems gives the full time evolution of the system. Likewise, the Boltzmann equation is often the starting point in classical gas dynamics.
...
4
votes
1answer
135 views
Calculating equation of motion using path integral
Suppose my action integral is $S=\int d^4x(\nabla \times A)^2$ and $\delta S$ gives $\delta S =\int d^4x [2(\nabla \times A).(\nabla \times \delta A)]$
I would like to calculate the coefficient of ...
4
votes
0answers
297 views
General equation of motion for elementary particles
Elementary particles can be grouped into spin-classes and described by specific equations, see below:
Is there a general Lagrangian density from which all these equations can be derived?
A ...
2
votes
1answer
291 views
Equations of motion for an inertial computer mouse
I'm struggling with a seemingly simple problem in 2D motion. It has been many years since I looked at basic kinematics and my mind seems to be too slow and confused now. Imagine we want to build a ...
1
vote
2answers
48 views
Does spatial coupling prohibit resonances due to an external source field?
The harmonic oscillator coupled to a sinodial external source
$$\tfrac{\partial^2 x(t)}{\partial t^2}+\omega_0^2 x(t)=F_0\sin(\omega_\text{ext}\ t),$$
has the solution
$$x(t)=x(0)\cos(\omega_0 t)+C ...
1
vote
0answers
61 views
Formulation of the Three-Body Newtonian problem
I am trying to understand three body problem in Newtonian space. I want to make formulation of differential equations for known initial conditions for the case with:
Identical three masses
...
1
vote
2answers
155 views
Is there any case in physics where the equations of motion depend on high time derivatives of the position?
For example if the force on a particle is of the form $ \mathbf F = \mathbf F(\mathbf r, \dot{\mathbf r}, \ddot{\mathbf r}, \dddot{\mathbf r}) $, then the equation of motion would be a third order ...
0
votes
3answers
144 views
Equation $H(q,p)=E$ is the equation of motion or energy-conservation law?
I do not completely understand, why do we consider Hamilton–Jacobi equation $H(q,p)=E$ as equation of motion, whereas it is looks like energy-conservation law?
0
votes
2answers
173 views
Question Concerning Position Of A Particle At Any Given Time
After years of procrastinating i've decided not to "move ahead" with physics without getting this ridiculously trivial question clear!*I know i had asked a similar question as silly and stupid as this ...
0
votes
1answer
123 views
Control system with equation C = A*x + B*dx/dt
This question came up in a computer science / robotics exam and I still don't know the solution for it. I figured out that it's classical mechanics related, so I thought this might be the best place ...
0
votes
1answer
177 views
Laws of Motion: Acceleration to be applied on a free falling object to reduce velocity to 0
Assume that an object of mass 'm' is falling to the earth.The force acting on the same would be F = m*g = 10m (assuming g = 10m/s^2). In this case the velocity of the object at time 't' = 10 seconds ...
0
votes
2answers
93 views
Given Angle, Initial Velocity, and Acceleration due to Gravity, plot parabolic trajectory for every “x”?
Given any Angle -> 0-90
Given any Initial Velocity -> 1-100
Given Acceleration due to Gravity -> 9.8
Plot every x,y coordinate (the parabolic trajectory) with cartesian coordinates and screen pixels ...
