The rotation tag has no wiki summary.
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Rotation of parabola
I'm designing a parabolic solar concentrator and am doing ray-tracing on Matlab from scratch. I'm beginning to look into compound concentrators and would need to have an equation for a parabola ...
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2answers
155 views
Exchange operator in terms of rotation operator
I have studied about exchange operators and rotation operators and I know that an exchange between 2 particles in a combined state is the same as rotating each particle 180 degrees (according to ...
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0answers
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Rotation in an 'empty' universe [duplicate]
Possible Duplicate:
Is rotational motion relative to space?
Assume a universe with the same physics as ours, but containing only one rotating (charge-free) body - let's say the size of the ...
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3answers
245 views
Rotational speed of a discus
I was wondering whether the rotational speed of a discus has any influence on the flight of the discus. Would slowing the rotation or speeding it up change the trajectory in any way or would the ...
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2answers
126 views
Would the arms of a rotating ice skater still move outwards if there was no other object in the universe?
If there is no other object in the universe apart from a rotating ice skater, then nothing can be used as a reference frame. Would it make any sense to say that the skater is rotating? If so, rotating ...
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1answer
60 views
Would we feel the rotation of a rotating habitat?
Assume that a space habitat is shaped like a can with the "top" open.
lets say we attach the can's top to a string with an astronaut standing on the base. We then rotate the can in deep space using ...
2
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1answer
143 views
Why can we use just one angular velocity vector to describe the rotation of a whole non-inertial reference frame?
The other day in class the professor was explaining non-inertial reference frames. We were working out how to find the acceleration of a point as measured from the non-inertial reference frame, and ...
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2answers
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Rotational kinetic energy during vertical circular motion of a particle
Why is it not necessary to take into account rotational kinetic energy when using the Law of Conservation of Mechanical Energy to solve vertical circular motion problems? After all, the particle is ...
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0answers
459 views
Rotating Disc and Magnetic Field [closed]
I'm studying for exams, and I am curious as to how the rotation of a disc would affect the magnetic field. The following problem stumps me:
A plastic disc of radius $R$ has a charge $q$ uniformly ...
2
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1answer
42 views
Who has succeeded in demonstrating the Lense-Thirring effect?
Who has succeeded in demonstrating the Lense-Thirring effect?
This effect is one that describes the rotational motion of the Earth from a space-time structure. This effect is the "drag" of the ...
4
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1answer
329 views
Is all angular momentum quantized?
Angular momentum is definitely quantized in elementary particles and electrons in atoms.
Molecules also have characteristic rotation spectra.
Is it true that all angular momentum is quantized, ...
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3answers
468 views
Shape of rotating rope (lasso problem?)
Let's take a wire or a rope. I usually do this with a chain or my scarf.
I fixate one end in my hand and apply rotation (by subtle movements of this endpoint like spinning a lasso). The rope gets ...
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1answer
162 views
Finding stopping time when only given initial angular velocity and an expression for angular acceleration?
Question:
A wheel starts is spinning at $27\text{ rad/s}$ but is slowing with an angular
acceleration that has a magnitude given by $\alpha(t) = (3.0\;\mathrm{rad/s^4})t^2$. It stops in a time ...
3
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1answer
164 views
What's a pseudo-rotation?
I'm sorry for this lexical, probably extremely elementary, question. But what is a pseudo-rotation? I just read this term for the first time, in the beginning of the 4th chapter book of CFT by Di ...
2
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1answer
85 views
Synchronising the Earth's rotation via mass redistribution
How much material would have to be moved per year from mountain-tops to valleys in order to keep the Earth's rotation synchronised with UTC, thus removing the need for leap seconds to be periodically ...
2
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1answer
415 views
Help understanding a Magnetic Levitation “Physics Toy”
I was shown a toy, yesterday, which I would like help understanding qualitatively.
A fellow engineer showed me a kit which included three main parts:
1.) A base (black box), approximately 4 ...
7
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4answers
399 views
Why does a ping pong ball change direction when I spin it on a table?
When I spin a ping pong ball on the table, it rolls forward in the opposite direction of the spin, and then eventually changes direction and rolls backward.
Here's a video demonstrating the effect.
...
2
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4answers
347 views
why does what get pushed away when centripetal acceleration is towards the center
If centripetal acceleration is towards the center, then why - when you spin a bucket of water (a classic demonstration) - does the water not get pushed out but rather stays in the bucket without ...
2
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1answer
180 views
What “I” should use in Rotational Energy formula $(I \omega^2)/2$
$\text{Rotational Energy} = \frac{1}{2} I \omega^2$. What $I$ should be used?
$I$ as a inertia tensor matrix = stepRotation * inverse moment of inertia * inverse stepRotation;
Or I as moment of ...
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6answers
550 views
Why does the earth rotate? [duplicate]
Possible Duplicate:
Why does every thing spin?
So why would the earth, or any planet for that matter, rotate along an axis? I know of no force which could come into play here, so i assume ...
1
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0answers
137 views
Error caused by pulley eccentricity [closed]
Not sure if this is perfectly a physics question:
A rope is wrapped around a cylinder of diameter D. The cylinder is slightly eccentric so that the distance between the axis of the cylinder and the ...
7
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4answers
8k views
Does the rotation of the earth dramatically affect airplane flight time?
Say I'm flying from Sydney, to Los Angeles (S2LA), back to Sydney (LA2S).
During S2LA, travelling with the rotation of the earth, would the flight time be longer than LA2S on account of Los Angeles ...
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4answers
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Are there planets that do not rotate on their axis?
I was reading a thread about how a pendulum would be affected if the Earth did not rotate and Larian's answer made me wonder if all planets rotate necessarily due to physics.
So that's the question: ...
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3answers
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MEMS gyroscope and orientation
I'm trying to understand how a MEMS gyroscope can give you orientation. The question may not make any sense, I may have some misunderstandings about the different topics...
From the wikipedia page ...
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3answers
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What frame(s) of reference are used to measure the rotation of the Sun around the galaxy ?
I can find various speeds and estimated durations listed at numerous places but none specifically describe the frame of reference.
Possible options as example of kind of answer I expect.
Local ...
3
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1answer
67 views
What exactly is the definition of motion and its relation to Mach's conjecture?
The notion of "movement" seems to be well understood in physics. In fact, I don't recall any physics text-book defining motion. Special relativity theory says that there is no absolute frame of ...
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2answers
218 views
Doubt concerning centripetal acceleration
What is the centripetal acceleration and angular velocity of a child located 8.2 m
the center of a carousel? The speed (size of the tangential velocity) of the child is
2.1 m / s
A train moves in a ...
12
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3answers
556 views
Why does each celestial object spin on its own axis?
AFAIK all the celestial objects have a spin motion around its axis. What is the reason for this? If it must rotate by some theory, what decides it's direction and speed of rotation?
Is there any ...
