# Questions tagged [rotational-dynamics]

A tag for questions about the mechanical interactions of rotating objects, including torque and angular momentum.

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### Does time period of a simple pendulum depends upon the moment of inertia of the Bob of pendulum or its shape?

Time period of simple pendulum is given by $T=2\pi {\sqrt{\frac{L}{g}}}$ Here L is the length of pendulum i.e. distance between the point of support to the centre of mass of the Bob. Now consider a ...
1 vote
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### How does normal force act on ring with a point mass on it? [closed]

I have been thinking about this situation, I have no idea how the normal force act of such a body. Here I have taken the point mass and ring of same mass m but please provide a general solution. So I ...
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### Can u tell whether Acceleration of point contact is correct or not for rolling with slipping (backward slipping)? [closed]

Rolling with slipping backward
1 vote
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### Definition of energy for a Lagrangian with constraints [duplicate]

Suppose I have the Lagrangian in spherical coordinates: $$\mathcal{L} = T=\frac{1}{2}m (\dot{r}^2 + r^2 \sin^2 \theta \dot{\phi}^2 + r^2 \dot{\theta}^2)$$ Where $T$ is the kinetic energy. Now suppose ...
45 views

### Choice of axis in analysis of gyroscopic precession

In many demonstrations of analysis of gyroscopic precession, the analysis goes on by choosing two axes, one about which angular momentum is calculated, another about which torque of gravity is ...
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### Concept of rotational equilibrium [closed]

Consider a rigid square plate of side length 'a' which can rotate freely about the point O in vertical x-y plane as shown in figure. Plate has a groove AB along its diameter. An insect of mass moves ...
1 vote
30 views

### Trajectory of Instantaneous center of rotation of a disc performing both rotational and translational motion [closed]

I am posting the specific problem I am dealing with for reference and then explain the part I am confused with. My Understanding and approach to the problem I identified that in the ground frame the ...
57 views

Consider a free body, not hinged about any point. If a force is applied to one end of the body, the body has a net nonzero torque about many points in space. About which will it rotate? Am I wrong in ...
26 views

### Equation of a bicycle Wheel in free rotation up to stop

I have measured the rotational speed of a bicycle wheel in free rotation up to stop and i would like to have the physical equation (it is not linear). I would like to compute the frictional losses in ...
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1 vote
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### In which direction does static friction acts on the spool when a force is given to it below centre of mass?

Here, we are provided with a spoolhaving moment of inertia I=kmr², where k is a numerical factor. I am in the confusion that how should we judge in which direction static friction would be applied, I ...
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### Connecting rotational period with period of oscillation

Recently I have been thinking about if rotational period is somehow related to period of oscillation for SHMs. My original question was how velocity of something impacting a spring affects its ...
1 vote
57 views

### How can you determine if a bar will tilt with 2 points of rotation?

Say we have the typical press machine in the gym to exercise your chest, it is usually helped with 2 points of contact and weights on the sides of the points of contact: (Sorry for the quality) How ...
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### Has anyone tested the Dzhanibekov Effect to see if the frequency of the 180 degree flip changes based on the objects speed or mass?

Rotation around axis 2, the intermediate axis of an object that is not perfectly symmetrical will flip 180 degrees while continuing to spin in the same direction. I'm curious if there is a way to ...
1 vote
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### Why does MOI of rectangle depend on length of diagonal of the rectangle? [closed]

If we have a rectangle of length $a$ and width $b$ my physics textbook showed that the MOI about the axis of rotation in the picture is given by \begin{align}\label{MOI rectangle} \dfrac{1}{12}M(a^2+...
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### Reason of object not leaving earth surface

The earth rotates around the sun at speed of approximately $18.5$ miles per second. And the escape velocity of earth is $6.96$ miles per second. So the speed of rotation is greater than the escape ...
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### Spin and orbital components of angular momentum

From what I have gathered, angular momentum in a system can be calculated about any point. However, I am having trouble grasping this, and below I suggest an imaginary situation where I try to apply ...
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### Combination of angular and linear acceleration

I was wondering how the angular and linear acceleration of a body in free fall interacted with each other. Let's imagine a man as a yoyo spinning around a string in free fall. It will have two ...
29 views