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I know that the time derivative of some quantity $r(t)$ in a rotating frame which rotates with angular velocity $\Omega(t)$ is related to the derivative in a fixed (i.e. inertial) frame by

$$ \Big(\frac{d}{dt}\Big)_{rot} r(t) = \Big(\frac{d}{dt}\Big)_{in}r(t) - \Omega(t) \times r(t) $$

However, how can the time derivatives of two rotating frames, each rotating with its own angular velocity $\Omega_1(t),\Omega_2(t)$, be related to each other? Is there a similar formula for this case?

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  • $\begingroup$ Just a thought, but it seems like you could express the time derivative in both rotating frames with respect to some inertial frame and then eliminate the time derivative of the inertial frame between them. $\endgroup$
    – Luke
    Commented Apr 27, 2022 at 21:43
  • $\begingroup$ Related : Velocity in a turning reference frame. $\endgroup$
    – Voulkos
    Commented Apr 27, 2022 at 23:57

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$$ (1) \Big(\frac{d}{dt}\Big)_{rot_1} r(t) = \Big(\frac{d}{dt}\Big)_{in}r(t) - \Omega_1(t) \times r(t) $$ where $rot_1$ denotes a coordinate system rotating at $\Omega_1(t)$ relative to the fixed system $in$. $$ (2) \Big(\frac{d}{dt}\Big)_{rot_2} r(t) = \Big(\frac{d}{dt}\Big)_{in}r(t) - \Omega_2(t) \times r(t) $$ where $rot_2$ denotes a coordinate system rotating at $\Omega_2(t)$ relative to the fixed system $in$.

From (1) and (2) $$\Big(\frac{d}{dt}\Big)_{rot_1} r(t) + \Omega_1(t) \times r(t) = \Big(\frac{d}{dt}\Big)_{rot_2} r(t) + \Omega_2(t) \times r(t)$$

Finally, $$ \Big(\frac{d}{dt}\Big)_{rot_2} r(t) = \Big(\frac{d}{dt}\Big)_{rot_1} r(t) + (\Omega_1(t) - \Omega_2(t)) \times r(t)$$

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