A tag for questions about the mechanical interactions of rotating objects, including torque and angular momentum.

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0
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1answer
141 views

Purely mechanical description of how gravity causes a gyroscope to precess

I know the vector equation that relates torque to moment of inertia and angular momentum. What I want to know is what physical mechanisms actually occur to keep the gyroscope from falling. Where is ...
2
votes
1answer
219 views

Push a box in a plane with friction. How to deal with the rotation?

Suppose I have a box (say, length-1m, width-1m, height-0.5m) on the plane with friction. I can apply a horizontal force in on the surface of the box. If the force doesn't pass through the center of ...
2
votes
1answer
135 views

Velocity of hitting the ground when falling forward

A friend of mine fell while he was snowboarding which led to a discussion. He mentioned that, in general, if your center of mass is traveling at a certain velocity, and you fall forward, your head ...
2
votes
3answers
103 views

Golf: spin direction resulting from striking out of the toe

If a golf club strikes the ball out of the centre of the club face with the club path on the target line through impact, and the face square to target, the ball will move towards the target with no ...
0
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1answer
221 views

Contradiction regarding friction of a rolling cylinder in an inclined plane

I came upon this while wondering whether the friction of a rolling cylinder on an inclined plane depends on the value of friction coefficient. now, $$f\leqq\upsilon N$$ Again after calculating I ...
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2answers
161 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 ...
0
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1answer
129 views

Block on cart, equation of motion

Consider a rigid block of $b \times h$ having mass $m$ on cart (as depicted below). The cart is given an acceleration $a$, this leads to overturning of the block. The angle of rotation is indicated by ...
3
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0answers
153 views

3 Axis Gryroscope with forced Precession and Limits of Motion

I am working a problem concerning a 3 axis gryoscope, the spinning mass is a magnet (dipole). This is part of a optical sensing device. The inner gimbal is for pitch rotation, and the outer gimbal is ...
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0answers
69 views

Is there any role of steering in turning?

I am aware of the practical requirement of turning the steering wheel to turn a car while going on a straight and even curved road. But in the proofs of turning of car on leveled or banked curves, ...
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1answer
89 views

Motion of Object in Rotating water [duplicate]

Water inside bucket is rotated (by spoon or something) to flow in circular motion. An object kept in the bucket tends to be at the center of the bucket. Why is that?
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4answers
147 views

Centre of instantaneous rotation problem

Is there a point of Centre of Instantaneous Rotation (CIR) for every type of motion or only for cases of rolling?
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1answer
244 views

Toppling of a cylinder on a block

A uniform cylinder rests on a cart.The height and diameter is given.coefficient of static friction is given.How can i find the minimum acceleration of block such that the block topples? Morever what ...
2
votes
1answer
105 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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4answers
7k views

How do bicycle spokes work?

As you know, it is quite obvious that Bicycle spokes attach the hub in the centre to the rim. What else do they do? If you compare the wheels today with the ones from ancient times, there are more ...
2
votes
1answer
139 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 ...
1
vote
1answer
1k views

What is happening to rotational kinetic energy when moment of inertia is changed?

I know this question is asked here a lot, but I just had to ask this to finalise the concept. When a system lets say a rod of length $L$ and mass $M$ is rotating with angular speed $omega_1$ its ...
2
votes
2answers
2k views

Where does a spinning figure skater's energy go when she slows down?

Today in physics class we were talking about angular momentum and rotational kinetic energy. My teacher used the classic example of a figure skater spinning on ice - when she pulls her arms in, her ...
8
votes
3answers
630 views

Where does the kinetic energy go?

A uniform cylinder was placed on a frictionless bearing and set to rotate about its vertical axis. After a cylinder has reached a specific state of rotation it is heated without any mechanical support ...
0
votes
1answer
171 views

Energy of a simple pendulum like device

If there is a device in which a ball is attached to a pivot by a rod of length R and it is left to oscillate by dragging it to one side so that it is completely horizontal, at any point on its decent ...
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0answers
100 views

Terminal velocity for rotating system

Suppose we have a small bob/ball attached via rigid rod to a pivot in a viscous medium and then rotated by a constant torque, will the system finally(after considerable time) rotate with constant ...
0
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0answers
67 views

Total energy of a rotating body?

I've no problems with the first part. However, I'm struggling with the last part of the question. The first thing I did is to find the a new moment of inertia for the whole system including the ...
0
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1answer
2k 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 ...
0
votes
0answers
103 views

Two disks on frictionless surface, demonstration

Consider a system composed of two plane disks, which we will designate as $D$ and $d$. Their radii are $R$ and $r$ respectively $(R>r)$. The disk $d$ is fixed over the disk $D$ and a ...
5
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1answer
158 views

Heat engines and “Angular momentum” engines?

We know that the theory of heat engines is that, if you accept the second law of thermodynamics, $\Delta S > 0$ then you can define temperature using $\frac{1}{T} = \frac{\partial S}{\partial E}$ ...
2
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3answers
3k views

Force applied to wheel in pure rolling motion at contact point with road

Suppose a wheel with radius $R$ is resting on a non-inclined surface. A torque $\tau$ is applied to the wheel center. In an attempt to prevent wheel from spinning, the ground applies a static friction ...