Recent content by wrobel

  1. wrobel

    A homemade mechanics problem: A beetle on a globe

    I think that the case when the mass distribution on the circle has rotational symmetry is completely different from the case when it does not
  2. wrobel

    A homemade mechanics problem: A beetle on a globe

    The angular velocity of the ball changes its direction relative to the ball-fixed frame (see the text attached) and thus it changes its direction relative to the lab frame. Thus, there is no fixed axis about which the ball rotates.
  3. wrobel

    A homemade mechanics problem: A beetle on a globe

    This contradicts the formulas attached.
  4. wrobel

    A homemade mechanics problem: A beetle on a globe

    here is my analysis
  5. wrobel

    A homemade mechanics problem: A beetle on a globe

    It's a bit funny because I have equations written down and you're just saying words :)
  6. wrobel

    A homemade mechanics problem: A beetle on a globe

    This does not follow from anything. The ball is a rigid body with a fixed point, and thus it has three degrees of freedom. It is not obliged a priori to rotate about a fixed axis.
  7. wrobel

    A homemade mechanics problem: A beetle on a globe

    The ball has three degrees of freedom
  8. wrobel

    Collection of Lame Jokes

    Text: 1) Let's solve a physics problem. There is a block hung on a string. A bullet shoots straight through the block and loses half of its speed... 2) Do you have any tasks about a little squirrel and nuts, please? 3) Sure! There is a little squirrel hung on a string... ps No squirrels...
  9. wrobel

    A homemade mechanics problem: A beetle on a globe

    I composed a problem and initially thought it could be solved by purely analytical means, but it turns out it cannot. The problem is as follows: a homogeneous ball of radius ##R## can rotate freely about its fixed center ##O##. Let ##J## denote its moment of inertia relative to an axis passing...
  10. wrobel

    A short proof of the Poincare Lemma

    I would like to share a concise proof of the Poincaré Lemma Theorem (Poincaré Lemma) Assume that a smooth ##k##-form (##k\in\mathbb{N}##) $$\omega = \sum_{i_1 < \dots < i_k} \omega_{i_1 \dots i_k} (x) dx^{i_1} \wedge \dots \wedge dx^{i_k}$$ is defined in a neighbourhood of the origin in...
  11. wrobel

    Housecat Reproduction

    I haven't checked it out myself, but I trust you.
  12. wrobel

    On Liouville's formula

    1. Transport of Differential Forms Let ##M## be a smooth manifold with local coordinates ##x=(x^{1},\dots,x^{m})^{T}##. Consider a ##k##-form ##\omega## depending on ##t##: $$\omega(t,x) = \sum_{i_{1}<\dots<i_{k}} \omega_{i_{1}\dots i_{k}}(t,x) dx^{i_{1}} \wedge \dots \wedge dx^{i_{k}}$$ Let...
  13. wrobel

    Rigorous Elementary Functions

    No, I haven't seen this paper. Thank you. I’m not an expert in algorithm theory and math. logic, but it seems he is addressing a scientific question and has obtained a new result. My goal is much more modest: it is purely educational and methodological
  14. wrobel

    Rigorous Elementary Functions

    The goal of this post is to formally construct the theory of elementary functions without gaps, from the perspective of a university-level analysis course. It is intended as a unifying overview for undergraduate students who have previously encountered these functions in school but perhaps...