6
votes
3answers
330 views

Do we need inertial frames in Lagrangian mechanics?

Do Euler-Lagrange equations hold only for inertial systems? If yes, where is the point in the variational derivation from Hamilton's principle where we made that restriction? My question arose ...
0
votes
1answer
99 views

How are fictitious forces related to my feeling?

This question arises when I am studying fictitious forces in an undergrad introduction to physics course. Suppose I am standing in an elevator with an acceleration $a$ directed upward. From the ...
28
votes
10answers
3k views

What is the Earth truly rotating about/revolving around?

Earth rotates on its axis and revolves around the sun, the sun revolves around the galaxy, the galaxy is also moving. So Earth's net rotation as observed from a fixed inertial frame consists of all ...
0
votes
3answers
168 views

How to create frame of reference?

Is this possible to create a inertial frame of reference in the earth? How it is possible?
2
votes
2answers
338 views

Foucault pendulum

The equations of motions for a Foucault pendulum are given by: $$\ddot{x} = 2\omega \sin\lambda \dot{y} - \frac{g}{L}x,$$ $$\ddot{y} = -2\omega \sin\lambda \dot{x} - \frac{g}{L}y.$$ What are the ...
3
votes
1answer
453 views

The form of Lagrangian for a free particle

I've just registred here, and I'm very glad that finally I have found such a place for questions. I have small question about Classical Mechanics, Lagrangian of a free particle. I just read Deriving ...
14
votes
2answers
2k views

Deriving the Lagrangian for a free particle

I'm a newbie in physics. Sorry, if the following questions are dumb. I began reading "Mechanics" by Landau and Lifshitz recently and hit a few roadblocks right away. Proving that a free particle ...
4
votes
2answers
521 views

What is the inertial frame that explains the Foucault Pendulum?

I know that the Foucault pendulum rotation in relation to Earth is a proof that the object is inertial in relation to the distant stars. But what makes them more important than the Earth? Are they an ...
1
vote
1answer
341 views

centrifugal force in static frame of reference

The other day we derived Kepler's third law. $$ \left( \frac{T_1}{T_2} \right)^2 = \left( \frac{r_1}{r_2} \right) ^3 $$ In order to derive this, you can look at a given planet that revolves around ...