Questions tagged [rotational-kinematics]
A tag for questions about rotational motion, including angular velocity and angular acceleration.
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Euler angles and inertia tensor
Please note: What I'm looking for is $\alpha_0$ and $\beta_0$ in a form similar to Eq.(3) that will eventually give Eq.(1). Note that the inertia tensor is not a rotation matrix so I'm not trying to ...
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Kinematics of a rolling disk on a static disk (variation of the Euler disk)
I'm puzzled by the following problem. Consider a simple tilted disk $\mathcal{D}$ of radius 1 (in any unit) rolling without sliding on top of a static horizontal disk $\mathcal{S}$. The normal $\...
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If a body is lying on a frictionless surface, and we give it an impulse, will it start rotating about its center of mass?
If not, about what point will it rotate? If we want to know about what point an object will rotate in questions like these, how do we figure it out?
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Concept of polarization in microwave rotational spectroscopy
I am trying to understand the concept of polarization of molecules after they are excited by a microwave pulse. The context is:
The complexes are produced in a pulsed supersonic jet expansion of a ...
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Rotation of a sphere on two different axes
You have a small globe, which is mounted so that it can spin on the polar axis and can be spun about a horizontal axis (so that the south pole can be on top). Give the globe a quick spin about the ...
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If a weak light source is attached to a string, and someone swing this light source in circle. It seems that this light source is brighter. Yes or no
It may be truly a question of life and death.
You know those glow sticks.
As a sailor it is a good idea to carry one on our lifevest.
Falling into the sea, those glow stick make a light source that ...
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Why is the angular speed at the axis of rotation of a rotating disc equal to the angular speed at any other point on the disc?
I was just reviewing classical mechanics problems on Khan Academy and got the following question:
I knew that the angular speeds at points II, III, and IV must be equal, but I'm not sure how you'd ...
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Non-Euclidean geometry of rotating disc
Landau, in his Classical Theory of Fields Textbook remarks (while explaining GR) that a rotating disc viewed from an inertial frame of reference will no longer remain euclidean since the periphery ...
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Can some one explain to me why, when I include translational kinetic energy ($\frac{1}{2}mv^2$), I run into problems dealing with rotational motion?
Overall, the problems I know when to use it are when there is something like a rotating pulley disk which has a string wrung around it and a block at the end falling down. Another place I know when to ...
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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 ...
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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 ...
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Do symmetric angular velocities lead to symmetric axis of rotation observed in a fixed frame?
It has been observed that some insects with relatively small stroke amplitudes (such as mosquitos) take advantage of a translating axis of rotation to generate lift where insects with larger stroke ...
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Thermal fluctuations in orientation of point particles
I am modeling group of point particles with 6 degrees of freedom each - 3 positional degrees of freedom and 3 orientational degrees of freedom. So, each particle has 3 position coordinates and a unit ...
user67800
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Model for rolling gears down a slope doesn't fit experiment
I have derived a model for what happens when one rolls a gear down a slope, and I have performed an experiment, however the experiment doesn't fit the model. Where did I go wrong?
The model
When a ...
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Motion of a catapulted point mass moving freely inside a spherical bucket
I am trying to study the motion of a point mass inside the bucket of a catapult.
The catapult is shooting downward (i.e. describing a rotation of 180° from the horizontal axis) and I would like to ...
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Foucault pendulum, where did I go wrong?
I wanted to approximate the number $N$ of periodes needed, such that the foucault pendelum turns one time. Though my result is off by the factor 2 of the results I found.
What I did: I assume the ...
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Translational acceleration due to rotation
Sorry for boring you, my friends. I am haunted by re-deducing an expression of translational acceleration in ANSYS theory reference about acceleration effect. It takes the form of:
$$\lbrace a_t^r \...
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How Burmester's theory converts rotary motion of the crank to linear movement?
I have been studying the mechanism of Klann's Mechanical spider and there it was written that by Burmester's theory it converts rotary motion of the crank to linear movement. I tried searching but how ...
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Why did Feynman tell "we cannot locate earth's angular position, but we can tell that it is changing"?
I was reading "Symmetry in physics" by Feynman, where he wrote:
If we perform sufficiently delicate experiments, we can tell that the earth is rotating, but not that it had rotated. In other words, ...
user36790
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Would a large, small mass object in orbit experience induced rotation
Imagine a large (multiple earth radii), very small-mass ring orbiting The Sun. Half of the ring would be closer to The Sun than the outer half. Since orbital velocity decreases with distance, two free ...
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Rotating Tank of Charged Liquid
Consider a long rectangular tank of dimensions a×b, where a≫b, that is rotating at a constant angular velocity and filled with an incompressible charged fluid. How would one find an equation ...
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Angular velocity versor
I am going back through the definitions of good old Euclidean vectors and trajectories to see whether when i was younger i missed important concepts.
In my notes, and reference book, i found that for ...
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How is momentum conserved in this collision with loosely-connected spheres?
There are three identical spheres. B and C are loosely connected with a light inextensible string, and A approaches B directly at some initial velocity $v$. There is no angular momentum.
A and B have ...
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Should the rotary vane damper torque be less than the load torque?
The rated torque of a rotary vane damper should be less than or more than the load torque?
In my opinion, if the rated torque is greater than the load torque of the damper, then I believe my ...
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Assistance in writing the rotational constraints of a spool, in rotational dynamics
I came across a very interesting problem involving rotational dynamics, from the series of Cengage Physics books, which was asked in an Indian competitive exam called KVPY.
Write the constraint ...
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Calculating $C$ in $I_{CM} = CMR^2$
I am a bit new here, so please excuse any errors I might make.
I am a student in an AP Physics C: Mechanics course and I am conducting an experiment where I am experimentally calculating the C values ...
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Textbook problem - Struggling with polar coordinates
Recently I am self-learning "Introduction to classical mechanics" by David Morin. There is a problem in chapter as stated below:
Walking east on a turntable
A person walks at constant speed ...
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Acceleration in rotating frame
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9.5.3 Velocity and Acceleration in a Rotating Coordinate System
Applying Eq. (9.8) to the position vector $\vec{r}$, we have
$$\...
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How translation, rotation and translation plus rotation of a body can be define particle by particle?
Let use simple example, a uniform rod with center of mass (COM) at the center of rod. The rod is in free space there are no other forces acting on it.
If we apply single force acting on a particle at ...
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What does tangetial velocity change during Conservation of Angular Momentum
Lets say that a particle connected to a string is rotating about an axis O with a uniform tangential velocity of u. Then, the string is pulled towards the axis to decrease its radius (say from r1 to ...
