Dr/Dt world coordinates problem

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SUMMARY

The discussion centers on the relationship between the operators Dr/Dt and dr/dt in the context of rigid body dynamics. The equation Dr/Dt = dr/dt - wxr is established, where wxr represents the angular velocity cross product. The user seeks clarification on the terminology for Dr/Dt and the proof that both operators follow the same rules. A contradiction is noted when applying the product rule, indicating a deeper relationship that requires further exploration.

PREREQUISITES
  • Understanding of rigid body dynamics
  • Familiarity with vector calculus and cross products
  • Knowledge of differential operators in physics
  • Basic concepts of angular velocity
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  • Research the terminology used for Dr/Dt in rigid body dynamics
  • Study the properties of the d/dt and D/Dt operators
  • Explore the implications of the product rule in vector calculus
  • Review the article on polyatomic systems linked in the discussion for advanced insights
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This discussion benefits physics students, mechanical engineers, and anyone studying rigid body dynamics and vector calculus, particularly those interested in the nuances of differential operators.

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Homework Statement


In rigid body, r is the position of a rigid body relative to world coordinates,
dr/dt is the rate of change of r in world coordinates.
I encountered the term Dr/Dt as the rate of change of r in world coordinates relative to the body coordinates system.
And that Dr/Dt = dr/dt-wxr
My question is, how does Dr/Dt is called? (terminology)
Also the operator D/Dt has the same rules as the operator d/dt, how do you proove it? There is some relationship to proove this, but what is this relation ship?


Homework Equations


Dr/Dt = dr/dt-wxr



The Attempt at a Solution


I tried to use Dr/Dt = dr/dt-wxr to proove that both operators has the same rules, but didnt succed.
In matter of fact, I found some contradiction.
For instance: d(AxB)/dt = Ax(dB/dt)+(dA/dt)xB
So D(AxB)/Dt = Ax(DB/Dt)+(DA/Dt)xB should also be true.
However using Dr/Dt = dr/dt-wxr showed that there is inequality.

Thank you.
 
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I prefer the notation

dr^s/dt=dr^b/dt-wxr

where r^s = space fixed r (with subscript s) and r^b = body fixed r

The d/dt operator is the same in both cases.

There's a good, but lengthy article here

http://python.rice.edu/~chem630/Polyatomics.pdf
 

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