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pppqqq
  • Member for 11 years, 2 months
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  • Rome, Italy
44 votes
12 answers
87k views

What do people actually mean by "rolling without slipping"?

16 votes
1 answer
3k views

Mechanical similarity in Landau

11 votes
1 answer
1k views

Calculating Green's function from Dyson's series without normal ordering

8 votes
2 answers
1k views

What are the differences (if any) between the Dyson's series definition and the "in/out" definition of the $S$-matrix

6 votes
1 answer
721 views

Landau&Lifshitz's derivation of the law of entropy increase - clarification

6 votes
1 answer
271 views

When (or what is the meaning of) $I \propto E^2$?

6 votes
1 answer
8k views

Definition of "intensive" and "extensive" properties

6 votes
1 answer
6k views

Effective mass in Spring-with-mass/mass system

5 votes
3 answers
823 views

When can one write $a=v \cdot dv/dx$?

5 votes
2 answers
541 views

Approximations in simple pendulum

5 votes
0 answers
186 views

Particle sliding on a semisphere - solving the differential equations analytically [closed]

5 votes
1 answer
3k views

Definitions in thermodynamics: temperature, thermal equilibrium, heat

5 votes
1 answer
1k views

Number operator in interacting quantum field theory

4 votes
2 answers
511 views

What is the exact relation between $\Theta ^\mu _\mu =0$ and conformal invariance?

4 votes
1 answer
679 views

Definition of Lorentz transformations as transformations of the universe?

4 votes
2 answers
787 views

First variation of the action in relativistic notation - Landau & Lifshitz "Classical theory of fields"

4 votes
1 answer
2k views

Integral of Sedov's self-similar solution to the spherical blast wave problem

4 votes
2 answers
1k views

The "stationary potential energy" condition for static equilibrium in mechanical systems

3 votes
3 answers
3k views

Virtual displacement and generalized coordinates

3 votes
2 answers
789 views

Extension to continuous in proofs of rigid body mechanics

3 votes
1 answer
6k views

Conventional definition of ideal fluid

2 votes
3 answers
1k views

Definition of quantum microcanonical ensemble in Landau & Lifshitz

2 votes
1 answer
164 views

Reality properties of auxiliary fields after Wick rotation

2 votes
3 answers
301 views

Physical interpretation of FRW normal coordinates

2 votes
0 answers
54 views

Non-equilibrium electronic distribution in the time-relaxation approximation - Which is the boundary condition?

1 vote
1 answer
95 views

How to incorporate nuclear wave-functions into V-A theory for $\beta$-decay?

1 vote
0 answers
121 views

Is there a "time-independent" formalism for scattering theory of time-dependent interactions?

1 vote
1 answer
415 views

What is the neatest way to describe a “non-autonomous” (lagrangian) system?

1 vote
1 answer
158 views

Mean value of the force in a collision problem

1 vote
1 answer
1k views

A discrete approach to the catenary