Recent content by luinthoron

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    B Simple reasoning that the equivalence principle suggests curvature

    I am a high-school teacher and a PhD. student. I am looking for ways to introduce my students to GR. In my treatment, I speak about the equivalence principle and later about curvature in general and consequently that of spacetime. I am missing a connection of these two parts that would be...
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    Projectile motion of a two-point rigid body

    I see. Since my goal is to practice the method on a simple situation first, I would go with linear air resistance first, regardless of the physical reality. I should also add that I am working with simple numerical solutions, first-order or second-order numerical methods. I could go further in...
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    Projectile motion of a two-point rigid body

    Fair point, but if I add air-resistance?
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    Projectile motion of a two-point rigid body

    Uniform gravity plus air-resistance confined to the plane of rotation, for start. But ultimately, I would like to be able to solve the rigid body motion under any kind of given forces.
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    Projectile motion of a two-point rigid body

    I would like to patch some gaps in my physics background. For example, I've been trying to come up with the sollution to the following: I have a model rigid body made up of two mass points and a massless rod connecting them. I throw the body with initial velocity under some angle of elevation...
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    Kerr metric and rotating stars

    I have recently come across the notion that Kerr metric describes the spacetime outside a rotating black hole but not outside a rotating (electrically neutral) star. Unlike Schwarzschild metric, which works both for non-rotating spherically symetric black hole without charge as well as any other...
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    How does metric give complete information about its space?

    Thank you for your posts. The thing is, I am trying to introduce the idea of curvature to high school students and I don't want to drown them in mathematics. The remark about Gauss and the actual mesuaring from jedishrfu seems to be in that direction. I'll dig more into it.
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    How does metric give complete information about its space?

    Hello, I've been struggling with the so often spoken idea that a metric tensor gives you all necessary information about the geometry of a given space. I accept that from the mathematical point of view as every important calculation (speaking as a physicist with respect to GTR rather than...
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    Why does special relativity exclude gravity?

    Although I find the discussion in the posted thread interesting, I fail to see the immediate connection with my question. I don't find answers including tensors very helpful at this point. I understand the mathematics and basic principles but the larger physical pictures eludes me.
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    Why does special relativity exclude gravity?

    Hello, I was unable to find a similar thread, so I would like to ask about this myself. I have several textbooks on SR and GR at my disposal but none of them gave me the answer to my question. I remeber from undergraduate course that SR brakes down if we want to include gravitation. I feel...
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    MTW Gravitation Ex. 25.16: Comparing Equations & Expressing u_0 in \tilde{L}

    Thank you for the advice. I ended up with: \begin{equation} \tilde{E}_0^2=4\tilde{L}^2u_0^3-\tilde{L}^2u_0^2+1 \end{equation} \begin{equation} 3u_0^2-u_0=-\frac{1}{\tilde{L}^2} \end{equation} The second one is a quadratic equation, so I can write the solution \begin{equation}...
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    MTW Gravitation Ex. 25.16: Comparing Equations & Expressing u_0 in \tilde{L}

    Hello, I am trying to work out this exercise for my personal research connected with my bachelor thesis. The task is to compare equations (25.42) and (25.47) and express $u_0$ in terms of \tilde{L}. I have so far put the two equations together getting \begin{equation}...
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    Derivation of geodesic equation from hamiltonian (lagrangian) equations

    Homework Statement Hello, I would like to derive geodesics equations from hamiltonian H=\frac{1}{2}g^{\mu\nu}p_{\mu}p_{\nu} using hamiltonian equations. A similar case are lagrangian equations. With the definition L=g_{\mu\nu}\dot{x}^\mu\dot{x}^\nu I tried to solve the...
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