百度 最终，恒大留下了高拉特，现在看来，高拉特对于恒大太重要了。
A tag for questions about the mechanical interactions of rotating objects, including torque and angular momentum.
243 questions from the last 365 days
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A Rolling Disk with a small ball soldered on its rim [closed]
A disk of mass M and radius R is constrained to roll, without slipping (pure rolling), on a horizontal plane. On its rim (inward), a small ball of mass m is soldered, whose dimensions are negligible. ...
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Toppling of a Table [closed]
A table has a heavy circular top of radius $1$ meter and mass $20\text{ kg}$. It has four light legs of length $1$ meter fixed symmetrically on its surface. What is the maximum mass that may be placed ...
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Are center of rotation and center of mass are same for an ellipsoid falling in water under gravity?
Consider an ellipsoid solid freely falling under gravity in water. The solid is free to rotate and translate inside water. If gravity is the only force acting, I understand that center of mass and ...
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Is angular momentum balanced locally?
So consider the balance of angular momentum for a system of particles
$$ \sum r_i \times F_{iext} = \frac{dL}{dt} \tag{1} $$
If no external forces are present, RHS vanishes, and thus, that implies ...
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Can there be wind and/or liquid currents driven by a planet's rotation?
Can the rotation of a planet alone provoke any kind of wind or liquid current?
Can the atmosphere, at least in some cases, have wind currents driven by the planet's rotation?
And can liquids also move ...
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What is the trajectory of a ball / ring released from a rotating disk?
Suppose a ball or ring is placed on a horizontal disk that is rotating at a constant angular velocity about its central vertical axis. Initially, the ball is held fixed relative to the disk so that it ...
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What causes road resistance of a tire?
Road loss of a bicycle tire is usually explained as the work of deformation, as the leading edge continually deforms upon contact with the pavement; i.e. the tire flattens. However, at the trailing ...
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Tilting of the Earth's rotation axis
Was the rotational axis of Earth tilted from the start? If not, then did the bulging of Earth at the equator cause the rotational axis to tilt? If so then what is the physics behind it?
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What proportions are necessary for a rectangular dice to roll a square side up 20% of the time?
I heard that an ancient version of the game Mia might have been played with cut knucklebones as dice, and be a little bit rectangular.
Is there a way to model dice face proportions with a rectangular ...
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Critical angle of rolling [closed]
I wondered when would a six sided polygon roll over because its COM on an incline as follows. Shouldnt it be when the line from center point to a vertex is vertical to the horizontal so half the angle ...
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A question on the motion of a rod rotating about a hinge
Consider the following typical setup
Here we have rod hinged to a point. Say, i apply non zero forces $F_1$ and $F_2$ are distance $r_1$ and $r_2$ as shown such that $F_1r_1=F_2r_2$.
Now if i measure ...
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Why is it not possible to rotate sphere on 2 axis simultaneously?
I have conducted several tests with a steel sphere to rotate it simultaneously on two axes. In none of these tests did I successfully achieve simultaneous rotation as intended. The sphere rotated ...
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Hard boiled egg vs raw egg rolling down an incline
We know that when spinning a raw and hard boiled egg the hard boiled egg will spin faster and the raw egg will turn the energy into internal heat. But when rolling down an incline the raw egg is ...
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What is the direction of rolling resistance?
I would like to know the direction of rolling resistance between an object and a surface. From my research, rolling resistance causes a torque around the center of mass of the object, and since torque ...
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How can a light string make a pendulum without becoming slack?
I have seen a lot of physics problems involving a bob hung using a light string from a hinge point and then we give some intial velocity $v$ in horizental direction Then its said that if $v \geq \sqrt{...
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