Circular motion about a central point or axis

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1answer
54 views

Is sun revolving around certain mass in space with reference to some other galaxy?

Every planet and satellite revolves around their mother planet and about their own axis as we know. So they are compacted as a system. Then why not sun?
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1answer
31 views

Deriving Rabi rotation matrix

I want to understand where the matrix: $$ \left|\psi(t)\right> = \binom{a(t)}{b(t)} = \begin{bmatrix} cos(\Omega t/2)&-ie^{i\phi_L t}sin(\Omega t/2) \\ -ie^{-i\phi_L t}sin(\Omega t/2) & ...
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1answer
23 views

Torque required to rotate panel on one axis

I am working on a project that requires solar panel to rotate around its axis, but I am struck with deciding the specs of the Servo Motor that is capable of doing this. Though, the panel hangs on its ...
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1answer
42 views

Calculating pitch and roll with accelerations greater than +/- 1g

I'm looking to compute the pitch and roll of a device fitted with a three axis accelerometer when it is not at rest or moving at a constant velocity. Most applications I've seen so far are for ...
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1answer
82 views

Explaining the restorative force in a bifilar pendulum

Ok so I am an A2 physics student, and for one of my pieces of coursework I conducted a practical investigation, my topic being the factors affecting the period and swing of a bifilar pendulum. The ...
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1answer
51 views

When does the angular momentum point in a different direction from the angular velocity?

I read this somewhere: $$\mathbf{L} = \tilde{\mathbf{I}}\mathbf{\omega}$$ In general, the angular momentum vector, $\mathbf{L}$, obtained from Equation above, points in a different direction to the ...
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3answers
135 views

Derivation of the general Lorentz transformation

The standard Lorentz transformation or boost with velocity $u$ is given by $$\left(\begin{matrix} ct \\ x \\ y \\ z \end{matrix}\right) = \left(\begin{matrix} \gamma & \gamma u/c & 0 & 0 ...
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0answers
50 views

2d pool collision with rotational motion

I'm trying to calculate two 2d disks' collision with rotational motion. The collision is perfectly elastic: the sum of translational and rotational energy is conserved. In the instant of the collision ...
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1answer
46 views

Can a solid Au nanoparticle rotate (i.e., spin) in a vacuum?

I think there are two cases, if it has an initial angular velocity, then it is supposed to rotate. If its initial angular velocity is zero, then the particle would not rotate. However, should a solid ...
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0answers
49 views

Derive time difference of phase rotated wavelets

I have one question concerning phase rotation of signals and I am not sure wether it works or not: Let's assume we have a zero-phase wavelet x(t) i.e. Ricker wavelet. Unfortunately, in our ...
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3answers
943 views

What is the cause of centripetal/centrifugal force?

What is the cause of centripetal/centrifugal force? When an object of mass $m$ is moved in a circular orbit, it experiences a centrifugal force radially away from the center. What is the cause of this ...
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0answers
41 views

Rotation motion like the number 8

I'm a college student majoring in culinology and I'm trying to find out the reason or method of the number 8 motion. Responses doesn't have to be in culinology examples, but that would be a great help ...
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0answers
59 views

Rotate the phase of a wavelet

Let's take a zero-phase Ricker wavelet which is given by: $$ \psi(t)=\frac{2}{\sqrt{3\sigma}\pi^{1/4}}\left(1-\frac{t^2}{\sigma^2}\right)e^{-t^2/2\sigma^2} $$ in the time domain which is often used ...
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1answer
41 views

Center of rotation and trajectory of a rigid body in a plane with applied *fixed* forces

This is my first question so please excuse me if my format is a bit off. Given a 2D rigid body with forces applied to it in such a way that the angle the force vector makes with the surface of the ...
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2answers
162 views

Different directions of frictional force when objects are rolling

My textbook has two instances of rolling bodies (smooth rolling). In the first, the body is rolling on the horizontal floor with some acceleration of its centre of mass. In this case, the book says ...
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1answer
77 views

Do particles rotate around themselves or they just move while the object rotates?

In this question, I'm not talking about particle spin. I guess, when an object rotates, its atoms also rotate. When an atom rotates, its particles must move in space. I wonder that if the particles ...
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1answer
36 views

Finding acceleration using rotational dynamics [closed]

I'm asked to find the linear acceleration of this object for a given tension $T$ knowing that both discs have mass $M$ and we don't consider the mass of the bar. The answer of the book is ...
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1answer
139 views

Does total angular momentum of the Earth-Moon system include individual rotational angular momenta?

To calculate the angular momentum of a body we need to specify a point (or an axis?) from which to define the displacement vector $\vec{r}$, so that $\vec{L} = \vec{r} \times \vec{p}$. For a rigid ...
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2answers
68 views

Is rotational motion conditioned to a central force?

We know rotational motion as a combination (a resultant) of two effects the tangential velocity and a centripetal force. Does rotational motion turn into linear motion at the same instance this ...
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2answers
138 views

Why do most of the motor with blades rotate anti-clockwise when viewed from the front facing the blade?

I have noticed that most of the motor with blades and engines rotate anti-clockwise direction when viewed from front facing blade. Is there any specific reason for this? Is it because of any kind of ...
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1answer
86 views

Can we calculate the frame dragging force of the Earth?

Although clearly this force would be significantly greater with a rotating black hole, is it still possible to calculate this drag for say a satellite orbiting the Earth?
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0answers
18 views

Deriving 'frame dragging' in elliptical coordinates?

I'm currently trying to derive the equation that demonstrates 'frame dragging'. I am familiar (of sorts) with the Kerr metric, but I am most comfortable working in cartesian/elliptical coordinates? ...
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2answers
60 views

Force needed to rotate a load horizontally? [closed]

I need to rotate a 500lbs(226.8kg and balanced at center of load) telescope horizontally, at up to 90 degrees per sec. Ideally I would like to reach the max speed in a tenth of a sec. I need to buy a ...
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1answer
71 views

Cayley-Klein Parameters

I have a very simple question(I guess )to ask $$\frac{d\mathbf{m}}{dt}= \mathbf{C} \times \mathbf{m}$$ where $\mathbf{m}$ and $\mathbf{C}$ are vectors. Assume that $\mathbf{C}$ is constant over a ...
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3answers
151 views

how apparent weight varies due to the rotational motion of earth

I learned that as the earth rotates about its axis, the bodies on the earth also follow a circular path. In most books I read, they give the example of a person standing on a weight balance at the ...
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1answer
75 views

Does the Earth's rotation affect an object in the stratosphere?

Does the Earth's rotation affect an object in the stratosphere? Example: I attach an object to a weather balloon and let it go at latitude +40.7, longitude -73.9 (New York). It goes up until it hits ...
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1answer
115 views

Sign wrong in angular momentum (Quantum Mechanics)

For small angles $\theta$ the rotation along a particular axis $n$ is given by $R(n,\theta)(r)=Id+ \theta (n \times r)+ o(\epsilon)$. Now, the rotation operator in Quantum Mechanics is given by ...
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1answer
371 views

How do I calculate the experimental and theoretical rotational inertia of a point mass?

I'm getting some weird results from a calculation I'm doing and quite honestly, I'm pretty sure it's my fault. I do have an apparatus involved for the experimental process for my lab but I don't think ...
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1answer
646 views

Does the Earth rotate vertically too?

We know that the earth has seen several Ice Ages. And we know the Earth's magnetic poles seem to flip once in a while. Could all of this be explained by a once every 250 Million Years or so the ...
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1answer
119 views

Is the spin 1/2 rotation matrix taken to be counterclockwise?

The spin 1/2 rotation matrix around the z-axis I worked out to be $$ e^{i\theta S_z}=\begin{pmatrix} \exp\frac{i\theta}{2}&0\\ 0&\exp\frac{-i\theta}{2}\\ \end{pmatrix} $$ Is this taken to be ...
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0answers
49 views

Stable planetary rotation states

In reading an article about theories as to how the slow retrograde rotation of Venus may have come into being, the article Why Venus Spins the Wrong Way (Franzen, 2001) stated that it is bound to ...
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1answer
67 views

Will we gain some extra hours if we travel in the direction of the rotation of the earth? [closed]

I heard that If we travel for long distances in the direction of the rotation of the earth, we can gain some extra hours in the journey. Is it true? What if we travel in the opposite direction?
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3answers
539 views

Angular Displacement

If something is rotating about a point and it covers a complete circle, should we take its angular displacement as 360 degree or 0? Please give link to some established material on this subject ...
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1answer
99 views

Molecular rotation - Energy levels for an asymmetric molecule

For a molecule with spherical symmetry, the energy level of rotation for quantum number $J$ is: $$E(J)=\frac{J(J+1)\hbar^2}{8\pi^{2}I}$$ "$I$" is the Moment of inertia for the molecule ...
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0answers
52 views

Rotation matrix for a coupled spin system

For an angular momentum basis with magnitude $F$ and magnetic numbers $m_F\in [-F,F]$, the unitary matrix that will perform the Euler rotations is the Wigner-D matrix of order $F$. I have applied the ...
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3answers
82 views

rotating an object without changing its orientation [closed]

I have a link hinged at one end and attached to a rectangular object via another hinge in the other end as shown. Now, I was wondering how would I maintain the orientation of the rectangular object ...
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3answers
120 views

What does “transform among themselves” mean?

I'm reading a script on atomic physics, and there's a chapter on irreducible tensors. I can't understand the meaning of "transform among themselves" in this context: An arbitrary rotation of the ...
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1answer
30 views

Reference for the polar parameterization of quaternions

I would like to find the original reference in which the polar parameterization of quaternions was given (i.e. the relationship between the components of a unit quaternion and the polar angles of an ...
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2answers
809 views

Which force makes a wheel roll down the hill? What causes friction?

A wheel rolling down a hill has two axis of rotation. One is where the center or mass is and the other is the point of contact with the surface which acts as a fulcrum. I was trying to understand ...
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2answers
387 views

Dynamics of counter-rotating flywheels

I've wondered about this for ages. If we create a pair of flywheels that rotate in the opposite direction with the same angular momentum, but are co-located and have the same mass and inertial moment ...
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2answers
183 views

Would box on the floor rotate?

There is a floor that friction is proportional to its velocity (like $F=-kv$) and there is a box with its width as $l$ and its height as $h$. (you may assume that $l$ is longer than $h$). It is on the ...
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143 views

As the earth rotates around itself, does this have any effect on the dynamics of flights? [duplicate]

As the earth rotates around itself, does this have any effect on the dynamics of flights? Or "shouldn't" this have an effect? Does flying in the direction of the rotation of earth around itself, or ...
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1answer
62 views

Vector Isolation/ Rotation

I have a series of vectors (current speeds) based on an ENU (East North Up) system. I would like to estimate the current speed of the water headed in a specific direction. In this example I am ...
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1answer
148 views

Rotating point in 3D space by Unknown rotation vector [closed]

I have a random point defined by: int x = rand.nextInt(9)-4;//-4 to +4 int y = rand.nextInt(4)+2;//+2 to +5 int z = rand.nextInt(9)-4;//-4 to +4 Y happens to be ...
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4answers
327 views

Is it correct that tires quickly get bald when used at high speed?

In my investigation, tires will quickly get bald if we ride a motorcycle at high speed. Is it correct? How to explain it in physics? Does the friction increase at high speed rotation? Update: The ...
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2answers
368 views

How to derive relation for time derivative in a rotating reference frame

I am looking for an appropriate derivation of the $(\frac{d}{dt})_{\text{laboratory}} = (\frac{d}{dt})_{\text{rotating}} + \omega \times $ relationship that enables one to calculate all desired ...
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9answers
2k views

What is the difference between translation and rotation?

What is the difference between translation and rotation ? If this were a mathematics site, the question would be at best naive. But this is physics site, and the question must be interpreted as a ...
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1answer
164 views

Finding frame of reference where angular momentum appears zero

Consider a isolated system of $n$ non-interacting classical particles. We can easily select a barycentric frame of reference, where total momentum will be zero, so we have our $\vec x(i)$ — ...
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0answers
31 views

Optics of a rotated spectacle lens [duplicate]

I have just discovered that if I rotate my left spectacle lens about the vertical axis by 10 degrees in one direction, the vision in that eye becomes much crisper. Note that the sphere and cylinder ...
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1answer
461 views

Force acting on a simple rigid body in space

so this is the question that's been bothering me: Say you have a simple rigid body in space that is at rest or travelling with only translational motion at a constant speed. Say that the body is ...