Questions tagged [rotational-dynamics]
A tag for questions about the mechanical interactions of rotating objects, including torque and angular momentum.
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Can adding weight to something make it tilt slower?
Let's say we have 2 sticks, both a meter long. We put both of them on the ground vertically. To the top of one of them we attach a weight. Then we tip both of them over and let them fall.
Assume ...
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Will a falling rod stay in contact with the frictionless floor?
Question
A uniform rod of mass $M$ is placed almost vertically on a frictionless floor. Since it is not perfectly vertical, it will begin to fall down when released from rest.
I have seen solutions ...
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Is a westward flying plane heavier than an eastward one?
I understand that you weigh less at the equator due to the increased centrifugal force. From my understanding, the faster you circle the Earth, the less your effective normal force you would feel, up ...
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What causes a rotating object to rotate forever without external force—inertia, or something else?
Someone told me that it is not inertia, but I think it is inertia, because it will rotate forever. In my understanding, inertia is the constant motion of an object without external force. Am I wrong?
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Why are angles so weird?
I'm potentially asking quite a stupid set of questions here but I'm wondering if there is some overarching theory about why angles, and "rotational" quantities which deal with them, have ...
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Can a car steer on a frictionless surface?
Do the front tires of a car act like gyroscopes, such that a car could steer on a frictionless surface?
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Physical meaning of the angular momentum
Still reading Classical Mechanics by Goldstein, I'm struggling on a very basic notion: angular momentum. I physically understand it as the momentum of an object rotating around something given a ...
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Can a ultracentrifuge be used to test general relativity?
With today's ultracentrifuge technology, they can spin so fast that the sample can be subjected to accelerations of up to 2 millions Gs. That is equivalent to two solar masses. Has someone tried to ...
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Why do we assume weight acts through the center of mass?
The weight of a body acts through the center of mass of the body. If every particle of the body is attracted by earth, then why do we assume that the weight acts through the center of mass? I know ...
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The sound of rotating helicopter blades
Why do helicopter blades make this pulsing, oscilating, slapping(?) sound?
Since their movement is smooth, shouldn't the sound be a similar, constant shush, perhaps increasing or decreasing in ...
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What makes a wheel spin?
I don't fully grasp what makes a wheel much easier to move than to push a solid block.
The pressure at the point of contact between a wheel and the ground must be pretty enormous compared to the ...
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Why certain rotations are unstable? (Euler Equations)
We have the Euler equations for a rotating body as follows
$$I_1\dot\omega_1+\omega_2\omega_3(I_3-I_2)=0\\
I_2\dot\omega_2+\omega_1\omega_3(I_1-I_3)=0\\
I_3\dot\omega_3+\omega_2\omega_1(I_2-I_1)=0$$
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What determines the angle of the cushion on a pool table?
If you look at the cushions (bumpers) on a pool table, you'll see that they're not vertical. They're tilted inwards. About 10 years ago, I came across a physics exam in which one of the problems ...
user4552
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If I toss a coin, vertically, on the surface of Mars, will it land back in my hand?
When I toss a coin in Mars, is the planets atmosphere rare enough that I'd rotate with the planet (at its angular velocity), but not the coin?
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Why is climate change triggering faster rotation?
On July the 29th 2022, the Earth finished its rotation about 1.5 milliseconds earlier than the entire 24 hours. Scientists link this to climate change, saying that a possible reason could be due to ...
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