# Questions tagged [rotational-kinematics]

A tag for questions about rotational motion, including angular velocity and angular acceleration.

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### Navier Stokes equations for rotating falling object

I am considering the problem of a rigid body moving in a fluid, free to translate and rotate (say, for example, a falling body in a fluid). Some of the approaches I found in some articles involve a ...
2answers
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### Is it possible that this electromagnetic field propulsion system would not violate any conservation laws? [on hold]

I have recently come up with a design of a conceptual electromagntic field propulsion system which should not violate any conservation laws, particularly the Law of Conservation of Momentum and the ...
3answers
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### What is the angular velocity in the center of a rotating disc? [on hold]

The center of the disc is its center of mass and the motion of the disc is purely rotational (no translation).
1answer
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### If $v_{contact,road}$ in rolling motion is zero, how the contact point still manages to move forward? [duplicate]

If velocity of contact point of a rigid body performing rolling motion w.r.t road is zero then how the point gets delocalised from its initial position after some time? My textbook says, At any ...
1answer
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### Sagnac Effect and clocks synchronization

I read this from "The Sagnac effect and its interpretation by Paul Langevin", in cylindrical coordinates $$ds^2=c^2t^2-dr^2-r^2d\theta^2$$ ...This transformation means that the observer O (...
1answer
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### A thin rod is standing on a smooth surface [closed]

A uniform thin rod of mass m and length l is standing on a horizontal surface. A slight disturbance causes the lower end of the rod to start falling. find the velocity of the centre of mass of the rod ...
2answers
49 views

### Addition of angular velocities

I'm trying to understand an argument in Taylor's Classical Mechanics section 9.3. Consider two frames, 1 and 2, and a body, 3. Let $\mathbf v_{21}$ be the relative velocity of frame 2 w.r.t. frame 1, ...
3answers
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### Is a rotating object moving or stationary?

Because it rotates in situ, its center of mass does not move, so it is static, but it is rotating, so it is not static, then is it static or moving?
3answers
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### Contradiction in Euler rotation Equation

By Euler rotation Equation, torque $$\tau (t)=I \omega '(t) + \omega(t) \times I \omega(t)$$ where $I$ is the inertia tensor in rotating frame and is constant; $\omega(t)$ is the Angular velocity in ...
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### Single number to quantify difference between two local reference frames?

I'm working with some satellite data that defines the spacecraft reference frame from two star cameras and two different measurements of orientation configuration of the cameras, and I'm trying to ...
8answers
483 views

### What actually is the vector of angular momentum?

If an object spins around a central point, it gets angular momentum which is a vector with an orientation dependent on whether its clockwise rotation or anticlockwise, i get that. But what the vector ...
3answers
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### What is wrong with this reasoning?

Suppose a particle is rotating about a point at a distance $r$, then since $r$ is constant $\frac{\text dr}{\text dt}=0$ so the component of velocity along the position vector should be zero. ...
1answer
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### Is there a reference frame in which the static friction from rolling does positive work?

I am worried this will be deleted as a duplicate question, so I will try to be extra clear what I am asking: In some reference frames, static friction can do positive work. If you have a crate in the ...
0answers
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### Could the source of dark energy be the universe rotating in a higher dimension?

As I understand it, the centrifugal force in a merry-go-round increases as we move further away from the center. Could the universe be spinning in a higher dimension (or even just spinning in a ...
3answers
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### Can a tilted wheel roll straight?

The common explanation of why a wheel that is falling to one side will turn towards that side to balance itself is gyroscopic precession, i.e. the torque produced by the falling of the wheel plus the ...