B Tangential Velocity (maybe)

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The discussion revolves around understanding tangential velocity in a circular motion context, specifically regarding points A and B rotating around a common center. The participants clarify that to determine the tangential velocity of point B, the initial positions of both points at time t=0 are essential. They explore the relationship between angular velocity and tangential velocity, emphasizing the need for mathematical expressions to describe these motions accurately. The conversation also touches on historical perspectives on planetary motion, referencing Ptolemy and Newton's contributions. Overall, the thread highlights the complexities of calculating tangential velocity and the importance of foundational knowledge in math and physics.
  • #31
kuruman said:
What additional description do you require?
Actually I want to know why B will start rotating?
 
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  • #32
I assume that vector A rotates about the origin, referenced to the x-axis.
Does vector B rotate relative to vector A, or relative to the x-axis ?

Which tangential velocity is required? Is it the rate of point B about the origin in rad/sec, or distance per second about the origin.
Or is it the instantaneous velocity of point B on the x, y plane ?

titasdasplus said:
Actually I want to know why B will start rotating?
Because it is specified as having an angular frequency.
What alternatives are there?
 
  • #33
haruspex said:
In that thread, I did show that the expression gave the right answer in a couple of special cases. Maybe you would find that more persuasive?
You were right, and my "suspicion" was wrong. I misinterpreted the requirement in the OP (see the "edit" in post #29).
 
  • #34
kuruman said:
Around 200 CE, Ptolemy came close to describing planetary motion within the geocentric model. He used the idea of epicycles which is essentially what we have here
Well, in this case we're describing the orbit of the Moon...
 

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