# Questions tagged [rotational-dynamics]

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

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### Why is the moment of inertia the rotational analog for mass and not inertia?

I've thought that both mass and the moment of inertia measure an object's inertia, one being in translational motion and the other in rotational motion. That has made complete sense to me, but in my ...
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### Would a homogeneous rod on a fulcrum oscillate or remain at rest after displacement?

If I take a homogeneous rod, put it on a fulcrum, push one side down in a controlled way and release very carefully won't the rod just stay at rest in that new position? ChatGPT says that it would ...
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### Conservation of linear vs. angular momentum in two similar cases

I have a question that eludes my understanding: Imagine we have a bullet of mass $m$ and a rigid pendulum with a bob of mass $M$ hanging from a rigid rod of negligible mass hanging from the ceiling ...
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### Two cylinders rolling without slipping on planks

I am struggling with the following setup. This setup consists of three massless planks and two massive cylinders, as can be seen from the figure. The lower plank is pulled with a force $F$ that ...
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### Coriolis force on a particle moving on sphere

Consider a particle moving on a rotating disc, as shown below. The direction of the Coriolis force acting on the particle can be found using the cross-product of the angular velocity vector and the ...
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### Do off-centre forces create additional energy?

When a force is applied to a rigid body at its centre of mass, it accelerates. Over time, that acceleration becomes velocity, which gives the body a certain amount of kinetic energy. However, if that ...
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### Motion of bowling ball

I'd like to model the motion of an asymmetric bowling ball thrown on a bowling lane. I know there's forward momentum and angular momentum that moment the ball is released, and there's of course ...
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### Avoiding secondary flow in rotating fluid

I am required to create an annular flume for an experiment. The flume is to be filled with water, and a paddle is to be dipped into the water and rotated along the flume at some fixed angular velocity ...
1 vote
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### Relationship between varying radius of ball and its affect on time taken for ball to come to rest in a spherical hemisphere while moving in a circle

I am a high school student trying to figure out the theoretical relationship between the radius of a ball that is launched into a bowl (moves in a circular path in the bowl) and the time taken for it ...
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### Spinning plate on the barbell

Suppose I have a plate and a barbell like the ones we see in the gym. When I spin the plat in the clockwise direction, the barbell also starts spinning in the clockwise direction. When I put my hand ...
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### How torque and linear force interact with forces on poles

When there are 2 forces normal to each end of a uniform pole, if they had the same force, the rotation would be cancelled out and all force would be acting in one direction. But if one force was ...
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### Does spinning the umbrella slow down the fall more?

Ignoring its structural weakness, if you jump from some height and use an umbrella to slow down the fall, would making it spin while you're falling affect the speed in any way?
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### Spring hanging on a spinning Disk

I have already asked a question on the Math stack-exchange. You can find it under the following link: https://math.stackexchange.com/q/4876146/ I felt like the question is better suited for this stack-...
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### Angular momentum ABOUT centre of mass (Investigating this IITJEE 2016 problem.....) [closed]

Note- By COM i mean the Centre of mass. In this question , I analyzed a problem in mechanics and encountered a difficult situation which the problem doesn't address (and so do my teachers ) ...... ...
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### Proof for conservation of angular momentum in rotating frame of reference

imagine a simple situation such that an object is rotating on a table about a rope as seen in the below figure now if i pull on the rope from the center , the radius of circular motion of the object ...
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### What happens if we prevent gyroscope to precess?

If we apply some torque to spinning wheel in a vacuumed space in body frame y axis, wheel try to precess due to gyroscopic effect but it will be prevented by obstacles as seen from picture, what will ...
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### Why is the centrifugal force multiplied by $\sin$ here?

I'm currently studying for an exam and wondering what the visual interpretation of this question would be. It's a multiple part question and the first question was describing the equilibrium angle of ...
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### A block on a smooth rotating table [closed]

Assume a block is placed on a slightly rough table. Now that table starts to rotate about its center. Why does the block move towards the edge and fall off? I heard somewhere that it is because of &...
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### How can we show that $((\vec v · \vec r) \vec r )'$ corresponds to Coriolis force?

We have: Position as $\vec r$ Velocity as $\vec v=(\vec r)'$ Acceleration as $\vec a=(\vec v)'$ Angular velocity as $\vec \omega = \frac{\vec r × \vec v}{r^2}$ Angular acceleration as \$\vec \alpha = ...
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### Where did the rotational energy come from? [duplicate]

Consider a floating static pencil in flat space with no gravity. If we apply an impact force F for a short time t to the pencil vertically, pencil must get a CM momentum Ft, and corresponding kinetic ...
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