Recent content by wrobel
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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- wrobel
- Post #22
- Forum: General Discussion
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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.- wrobel
- Post #20
- Forum: General Discussion
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A homemade mechanics problem: A beetle on a globe
This contradicts the formulas attached.- wrobel
- Post #16
- Forum: General Discussion
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A homemade mechanics problem: A beetle on a globe
here is my analysis- wrobel
- Post #13
- Forum: General Discussion
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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 :)- wrobel
- Post #12
- Forum: General Discussion
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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.- wrobel
- Post #6
- Forum: General Discussion
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A homemade mechanics problem: A beetle on a globe
The ball has three degrees of freedom- wrobel
- Post #3
- Forum: General Discussion
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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...- wrobel
- Post #24,049
- Forum: Fun, Photos and Games
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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...- wrobel
- Thread
- Replies: 23
- Forum: General Discussion
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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...- wrobel
- Thread
- Replies: 0
- Forum: General Discussion
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Housecat Reproduction
I haven't checked it out myself, but I trust you.- wrobel
- Post #29
- Forum: General Discussion
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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...- wrobel
- Post #2
- Forum: General Discussion
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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- wrobel
- Post #3
- Forum: General Discussion
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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...- wrobel
- Thread
- Replies: 3
- Forum: General Discussion