Why is velocity in body fixed frame equals to angular veloc?

In summary, the conversation is about how to understand the equations for velocity and angular velocity in different frames. The first equation shows the relationship between velocity in the inertial frame and position in the body fixed frame. The second equation relates velocity in the body fixed frame to angular velocity in the body fixed frame. The conversation also mentions the angular velocity in the inertial frame and provides a reference for further explanation. The conversation ends with a request for help in understanding the equations.
  • #1
AntoineCompagnie
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0

Homework Statement


I don't understand, physically speaking, how do we get from the first equation to the second: how do we get the fact that velocity in body fixed frame equals to angular velocity in body fixed frame.

Furthermore I dont' understand how we get the angular velocity in inertial frame:

Homework Equations



\begin{align*}\underbrace{\dot q}_{\text{Velocity in inertial frame}}&=\underbrace{\dot R p}_\text{Position in body fixed frame}:\hat \omega^b\ \text{This okay for me}\\
\underbrace{R^T\dot q}_{\text{Velocity in body fixed frame}}&=\underbrace{R^T\dot R p}_\text{Angular velocity in body fixed frame}\text{I don't understand}\end{align*}

the angular velocity in inertial frame

\begin{align*}\underbrace{\dot q}_{\text{Velocity in inertial frame}}&=\underbrace{\dot R R^Tq}_\text{angular velocity in inertial frame}:\hat \omega^s \ \text{I don't understand}
\end{align*}

The Attempt at a Solution



My callsmate told me in the bus that he wasn't sure if my equations were quite right...Can you help me understand these equations?
 
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Related to Why is velocity in body fixed frame equals to angular veloc?

1. Why is velocity in body fixed frame equal to angular velocity?

In simple terms, velocity in the body fixed frame refers to the speed at which an object is moving in relation to its own coordinate system. On the other hand, angular velocity refers to the rate of change of an object's angular position with respect to time. These two velocities are equal because they both measure the movement of the same object, but from different perspectives - one from the object's own frame and the other from an external frame.

2. How is velocity in body fixed frame calculated?

Velocity in body fixed frame can be calculated using the formula v' = R * v, where v' is the velocity in the body fixed frame, R is the rotation matrix that describes the orientation of the body fixed frame with respect to the external frame, and v is the velocity in the external frame.

3. What is the significance of velocity in body fixed frame in physics?

Velocity in body fixed frame is an important concept in physics as it allows us to understand the movement of objects in a three-dimensional space. It is particularly useful in the study of rotational motion, as it helps us describe the velocity of an object from its own reference frame, which may be rotating or moving in a non-uniform manner.

4. Can velocity in body fixed frame be negative?

Yes, velocity in body fixed frame can be negative. This simply means that the object is moving in the opposite direction to the positive frame of reference. For example, if the body fixed frame is rotating clockwise and the object's velocity is measured to be negative, this indicates that the object is actually moving in a counterclockwise direction with respect to the external frame.

5. How does velocity in body fixed frame affect the motion of an object?

Velocity in body fixed frame is a key factor in determining the dynamics of an object's motion. It affects the object's acceleration, which in turn determines how the object will move in relation to its surroundings. Understanding velocity in body fixed frame is crucial in predicting the behavior of objects in rotational motion and can help us design and control various mechanical systems.

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