# Tagged Questions

The time derivative of angular position used when studying rotating objects or systems.

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### Too big to revolve like an atom? [closed]

At what point do objects naturally start revolving as a disk? From an atom, with which the electron revolves as a sphere, to a galaxy, that revolves in the same direction? I herd about rigid ...
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### Frequency's relationship to Angular velocity? [closed]

I have an issue regarding the concept of getting the angular velocity. I know that angular velocity relationship to frequency is w=2π*f, however I have a problem where a right circular cylinder with ...
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### Acceleration in full-swing pendulum

Consider a $360^{0}$ swing pendulum with a massless rod. If I start it from the position of unstable balance, at the very top of the circumference, according to the conservation of energy, its ...
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### Special Relativity - oscillator paradox

I am reading about the Special relativity and the original Einstein papers from 1905 and 1920 where he derives the Lorentz transformation and the effects of the time dilation and space contraction ...
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### Protecting astronauts from G's when taking off/landing

When landing from orbit or launching from the ground to orbit (with chemical rockets or other means of fast acceleration), could one place the astronauts in a centrifuge and spin it to protect them ...
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### What is $\omega \times v$?

I found that equation in my textbook. It says that $\omega \times v$ ($v$ is velocity) is centripetal acceleration. But how is the equation derived?
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### Centripetal force: if radius decreases, does ANGULAR or TANGENTIAL velocity change?

Having conceptual trouble with this aspect of centripetal force. Say we have a puck on a frictionless table attached to a string that I am holding through a small hole, so that the puck moves in a ...
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### Angular momentum of rolling sphere [closed]

A sphere of uniform density $\rho$ and radius $r$ is rolling without slipping on a perfectly flat surface. It is moving in a perfectly straight line and its axis of rotation is parallel to the plane ...
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### 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 ...
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### Proof of constant angular velocity in rigid body motion

I'm studying rigid body motion on Landau but I'm having troubles to understand this proof of the fact that the angular velocity $\vec{\Omega}$ is constant for a rigid body. My doubt is about the ...
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### Why does a ball rotate sometimes when you throw it?

My guess is that when you throw a ball, which is held by your hand, using you arm, the radius of the circular path being constant, the outermost part of the ball has a bigger radius than the innermost ...