Circular motion about a central point or axis

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0answers
36 views

Why does the centrifuge work backwards? [on hold]

Let's suppose, there is a big round recipient spinning in the air. If we throw some dirt in it, all the dirt will fly around in the recipient until all the heavy parts will stick on the walls of the ...
1
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0answers
32 views

Are there characteristics that distinguish our universe?

Are there any defining characteristics of our universe that could be different for other universes (or "instances of our universe") that operate under the same laws of physics? And which, if any, are ...
0
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0answers
27 views

Rotation operation on spin-1/2 particles

How does rotation operators work on a particle? What does it do on the particle conceptually? Also does particles spin on its axis?
3
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3answers
31 views

Why does a pot start rotating when coffee is stirred inside?

I usually make Turkish coffee as my morning coffee. I have a small somewhat rounded pot with handle on one side. I noticed that when I pour water in and start stirring, pot has a tendency to start ...
2
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4answers
120 views

Rotation of a vector

Is a vector necessarily changed when it is rotated through an angle? I think a vector always gets changed because its projection will change, and also its inclination with axes will always change. ...
0
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3answers
63 views

Rolling dynamics of round objects down an incline

If a cylinder is rolling down an inclined plane with inclination $\theta=30^\circ$ (with coefficient of static friction between cylinder and the plane $\mu_s=0.8$) without slipping and it has mass ...
0
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2answers
25 views

How to calculate the acceleration, if the mass-center is not on the force-vector's line (2D)

In a 2D plane there is an object, whose center of mass is at the $P$ point. The mass of the object is $m$. We apply a force $\vec F$ at the point $A$. If the center of mass is on the line, defined ...
4
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0answers
38 views

Why rotating reference frames are not inertial? [duplicate]

Let's say I'm standing on the equator, and that there is no other reference point in the sky. If the planet is rotating, then I measure my weight to be lower than if it is not. But given that I have ...
0
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1answer
15 views

Moment of Inertia for objects moving in a circle?

I have been treating objects moving in a circle as a hoop, where $I=MR^2$ and it's been working but I feel like it works for a different reason from what I'm thinking. How do you actually find the ...
1
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5answers
86 views

Rolling without slipping taking the contact point as pivot

I'm confused about this "rolling without slipping" kind of situation. Or better in this case the object is rolling and slipping, just use the label "rolling without slipping" to identify the kind of ...
0
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1answer
25 views

For a rolling object, is the tangential velocity the same as the velocity of the center of mass?

For example, a solid disk rolling down a hill would include both rotational and linear kinetic energy. For the rotational kinetic energy ($\frac{1}{2}I\omega^2$) the angular velocity becomes $v/r$ but ...
0
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2answers
35 views

Why does the angular speed formula end up in radians per second?

So, in my homework I am given the radius and also the tangential speed $v$, the measurement for radius is meters; the measurement for $v$ is $m/s$. I don't understand how by after calculating the RPM ...
0
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3answers
49 views

Rotation of rigid body with two different angular velocities

Consider a cylinder that rotates about a vertical fixed axis with angular velocity $\vec{\Omega}$ while rotating about a vertical axis passing through its center of mass with angular velocity ...
0
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3answers
61 views

Direction of deflection of Coriolis force on Earth

I'm a bit confused about Coriolis force direction on Earth. The observed deflection is to the right in the northern emisphere and to the left in the southern one. But what about an observer in the ...
0
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3answers
44 views

Axis of rotation and rotating rigid body [on hold]

We know that angular momentum of a solid disk rotating with angular velocity $\omega$ is given by $I\omega$ about its center. Now if I chose any axis (parallel to above), will it have same magnitude ...
0
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1answer
34 views

Coriolis object deflection and conservation of angular momenutum

I'm trying to understan kinematic inertial explanation of the apparent deviation of objects due to fictitious forces in rotating Earth. Take an object moving from the equator northwards, or ...
1
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1answer
36 views

If a rotating ball gets disintegrated to dust or energy what happens to its angular momentum?

Say a rotating ball or neutron star gets completely annhilated to energy by meeting its anti-matter counterpart (also rotating in the same direction), what happens to the angular momentum? It cannot ...
0
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1answer
30 views

Tension as a function of distance from the centre of a rod AB rotating about its end A [duplicate]

My confusion is- 1) While taking limits, tension at end B of rod is taken 0, The function comes showing maximum Tension at end A. But it seems to me that that at end A, T must be 0 as x=0 and at end ...
1
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1answer
18 views

Angular velocity and velocity of CM indipendence in rigid body motion

In the most general case, in rigid body motion the linear velocity of the center of mass $v_{cm}$ and the angular velocity of the rigid body $\Omega$ are not related with each other. Which condition ...
0
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1answer
24 views

Derivative of angular momentum of rigid body

I found this equation that describes the change in angular momentum $\vec{L}$ of a rigid body rotating about a fixed point $O$. $I_o$ is the moment of inertia of the body with respect to the axis of ...
0
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1answer
17 views

Calculation of support reaction in rigid body rotation and collisions

I can't understand the logic behind the calculation of torques exerted by supports in rigid body motion, especially rotation. The equation of angular momentum is ...
1
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3answers
67 views

Rolling without slipping in absence of friction force

I'm confused about a rolling without slipping situation. Suppose to have a disk of radius $R$ on a floor, and exert a horizontal force at a certain distance $r$ from the center of mass. I would like ...
0
votes
1answer
32 views

How to simulate an accelerometer in code

I want to write a simulation of an accelerometer (with a fixed X and Y axis in this case but with respect to a world coordinate frame) on a stick, rotating in a circle around a fixed point. From that ...
-1
votes
1answer
25 views

Could gyroscopes be use to control orientation of satellite?

In the game space engineers, the player can control the angular movements of a spacecraft with gyroscopes. Just to be clear, the purpose of this gyroscope is not to measure rotation, but to actually ...
2
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1answer
50 views

Contraction of a rotating system

Consider a system of two masses that rotates with constant angular velocity. When a force contracts the system the velocitie of the two masses increase. I understand this in terms of conservation of ...
0
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1answer
29 views

Instantaneous axis of rotation of a rigid body

For the description of rigid body motion, any point $O$ of the rigid body could be taken as reference, since the velocity of a generic point $P$ can be written in function of the angular velocity ...
1
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1answer
60 views

Calculate the distance from the axis beyond which the particles have slid off a rotating disk

A collection of small particles is distributed on the top surface of a disc that is rotating at 91 revolutions per second, about an axis, which is vertical. Some of the particles slide off, and some ...
0
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0answers
13 views

Finding the inner rotational velocity of a vortex incrementally

This is for improving accuracy in a prototype hydro design spreadsheet. Hypothetically: In a 6.6m tank, water enters tangentially at 0.575m^3/s with a velocity of 0.7m/s. The height of the resulting ...
2
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3answers
33 views

Force at axis of spinning wheel

This is a newbie question, but I don't quite understand the forces at work when an object is rotating. So I've read that i can use my right hand to determine the direction of the force at the axis ...
0
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1answer
62 views

Why does a force parallel to the axis of rotation do not produce torque? [closed]

One explanation can be that Torque is a cross-product (r x F). I want to know what is its physical interpretation.
0
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0answers
8 views

What is the analytical approach for a fiber cutting machine?

Folks, so today in the Lab I came up with this problem (see picture). It shows a cross section of a cutting machine. There's a blade moving with a constant speed dx/dt towards the center of the roll ...
1
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0answers
51 views

Clarification regarding Eq. (2.6.21) Weinberg Vol. 1

While reading the action of time reversal operator for massless particles, I was going through the derivation for Eq. (2.6.21) from Weinberg Vol. 1 which proceeds as follows $$ \begin{aligned} ...
2
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0answers
13 views

What force is needed to turn the Earth Pole-over Pole. Eg. UK now on Equator? [closed]

Specifically, if someone could specify the Joules energy required to force the Earth to slowly rotate the poles end-to-end by say 1 degrees rotation, and by 5 degrees. To be clear I mean to literally ...
1
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1answer
60 views

Understanding Euler's rotation theorem

According to Euler's rotation theorem, simultaneous rotation along a number of stationary axes at the same time is impossible. If two rotations are forced at the same time, a new axis of rotation ...
0
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0answers
51 views

Will future spaceships for very long distance rotate?

I have seen in the movie Interstellar and The Martian they use the model of spaceship which rotate around it's axis. This is the spaceship model from Interstellar. This is spaceship model from The ...
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0answers
20 views

Feasiblity of a long spinning top using an electromagnet to pull on Earth's magnetic field

Would it be feasible to build a infinitely spinning top (ref. Inception) by including a battery powered electromagnet who's polarity flipped in sync with the top's rotation such that the pull against ...
0
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1answer
45 views

Rotational motion: A cylinder, sphere and hoop rolling down a ramp [closed]

I have a question about comparing different objects in rotational motion. In this scenario: A cylinder (with moment of inertia = $\frac{1}{2}MR^2$), a sphere ($\frac{2}{5} MR^2$) and a hoop ($MR^2$) ...
2
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1answer
25 views

Can a tidally locked planet have a horizontal rotational axis?

Is it hypothetically possible for a planet to be both tidally locked, and still have a rotation "horizontally"? Where the substellar point would in effect be like the point of a top, spinning and yet ...
1
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2answers
65 views

Energy of a body in circular motion?

I'm confused about energy of a body in circular motion. In particular I'm having trouble to find the correct answer to this question. Consider the body in the picture that is set in motion from ...
0
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0answers
23 views

Angular velocity in body frame to displacement in lab frame?

For the case of a freely spinning symmetric top (no gravity), I derived the following equations, where $\omega_i$ is the angular velocity about a body-fixed axis: $$ \omega_1 = w_1 \cos (w_3 t) $$ $$ ...
1
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2answers
53 views

Does orbital motion cause rotation?

Assume the moon was flying freely in space, and not rotating at all. If if then happened to pass earth at just the right distance and velocity to fall into orbit, would its absolute rotation be ...
0
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0answers
47 views

Rolling Resistance Coefficient

I found that rolling resistance can be expressed with this equation: $$F_\mathrm{rr} = \frac{C_\mathrm{rr} W}{r}$$ Where $C_\mathrm{rr} =$ coefficient of rolling resistance $W =$ normalforce $r ...
0
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1answer
40 views

Angular acceleration from torque and radius

The story is about wheel. I have a wheel and I need to know it's actual angular velocity(which doesn't mach Vcar_longitudal / r). What I have access to is torque ...
2
votes
2answers
60 views

What happens to a body if it rotates extremely fast?

I am thinking on a object, e.g. ball or planet that starts rotating with increasing speed. Let's assume that his speed get's closer to the speed of light, what happens to this object? There are ...
-6
votes
1answer
72 views

Change of Earth's Rotation [closed]

At the time of global warming, all the ice will melt, resulting the reduction in spinning of earth, Initially. But, if earth's surface temperature rises continuously for a long time, exactly this will ...
-1
votes
1answer
43 views

Vectors finding direction include the difference between “north of east” and “east of north”

In what direction is your friend from the starting point after skiing 3 km east and then 1.5 km north? so far I know that angle= tan-1(opp/adj)=(1.5/3.0) angle= ...
0
votes
2answers
108 views

What is the difference between vortexing and centrifuging?

I understand that vortexing will result in mixing / re-suspension of particles, and that centrifugation will result in the separation of particles. However, what is the difference in the physics that ...
0
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1answer
48 views

How to show the finite rotation of a spin-1/2 system?

I'm reviewing my quantum mechanics by going through Sakurai and Napolitano again and working out all of the derivations. I'm stumped (though I probably shouldn't be) on some algebra in the finite ...
2
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2answers
107 views

Can an angle be defined as a vector?

In Classical Mechanics angular velocity, angular acceleration, torque and angular momentum can be defined as vectors with clear advantages such as the possibility to use vector product to simplify ...
0
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1answer
38 views

Angular velocity when a rod inclined to a wall slips and its subsequent motion observed from the axis of rotation

When a rod inclined to a wall slips, rate of change of which angle does the angular velocity represent? Is it the rate of change of angle with which the rod is inclined to the horizontal ? I'm not ...