0
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0answers
24 views

How to deal with a box on a plane from the perspective of a non-inertial frame of reference?

I'm having a hard time trying to understand how combined translation and rotation happens when analyzed from a non-inertial frame of reference. I've read that second law of motion doesn't apply to a ...
1
vote
1answer
13 views

How to calculate angle of inclination attained by a weigh balance on unequal loading?

Actually I need to rotate the beam (pivoted at centre) with constant angular velocity using the priciple of mass imbalance. Could anyone suggest what would be rate of decrease of mass in one pan ...
0
votes
1answer
19 views

Angular momentum of a sphere moving vertically downwards [closed]

If a solid sphere is moving vertically down with a velocity $v$ and spinning with an angular velocity $\omega$, what is the angular momentum of the sphere about an axis through the sphere which is at ...
2
votes
2answers
47 views

How to model energy loss in a rotating body?

I recently asked a question about modeling instability in a rotating rigid body. I now realize that I was mentally confounding two different effects: The "Dzhanibekov effect" in which a rigid ...
1
vote
1answer
63 views

An electromagnetic induction problem [closed]

The question goes like this : A thin non conducting horizontal disc of mass $m$ having total charge $q$ distributed uniformly over its surface, can rotate freely about its own axis. Initially ...
1
vote
1answer
45 views

A pretty dumb question on observation

Very often I have seen, that a bicyclist can balance himself better, while in motion, than he can while at rest(with his legs on the paddles of the bicycle). Now, I know that objects, say, a disc ...
0
votes
0answers
38 views

Rotating and moving reference frame

I've looked through your forums and can't find exactly what I need. I have a two objects whos dynamics can be described in discrete time as follows: $x_A(k+1) = x_A(k) + ...
-1
votes
1answer
54 views

Angular velocity of precession

So in my textbook they say this ${\rm d}\theta$ = |$d\vec{L}$|/|$\vec{L}$| $d\vec{L}$ is the change in angular momentum caused by a torque whose vector is perpendicular to $\vec{L}$, which is the ...
1
vote
1answer
40 views

Constant power in rotational dynamics

I am having trouble understanding and applying the concept of constant power (e.g. a motor) in rotational dynamics. We have that: $$P=\tau\omega$$ Therefore if we imagine a physical system with a ...
6
votes
1answer
163 views

Terminal velocity?

I am having a problem with a particular concept. Here is where I have gotten, since the ball never loses contact with the stair, it will rotate around through the edges, the edges being the pivot, ...
1
vote
2answers
119 views

Rod sliding on a frictionless surface

A uniform rod$(m,l)$ is standing vertically on a horizontal frictionless surface. Gravity is downwards and uniform. I give its upper end a little push and off it goes. I want to find the Normal ...
3
votes
0answers
65 views

Why does the video recorded by a falling, rotating camera seem to stabilize?

Here is a video of a GoPro falling from a plane: http://www.youtube.com/watch?v=QrxPuk0JefA Any idea what is happening when the image "stabilizes" around 0:35? I think it is because the camera's ...
0
votes
2answers
376 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 ...
2
votes
1answer
86 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 ...
2
votes
2answers
1k 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 ...
0
votes
2answers
563 views

Between a solid and a hollow cylinders of the same mass, which one has the greater rotational kinetic energy?

I know that rotational kinetic energy is $\frac{1}{2}I\omega^2$. Therefore, the rotational kinetic energy will depend on the moment of inertia. I came to the conclusion that since both have the same ...
0
votes
0answers
66 views

Gravitational Behavior of Rotating Body

Consider a stick with a (ball-shaped) weight at the end of it. Let's say this stick is in a state of rotation (it's floating in vacuum) and is also in a state of translational motion. Consider a ...
3
votes
5answers
1k views

Veritasium - Firing bullet in block - along center and away from center

This question is about this video on YouTube, in which a bullet is fired vertically into the center of a wooden block from below, sending the block up into the air. Next, a bullet is fired vertically ...
0
votes
3answers
347 views

Conservation of Angular Momentum, as related to a flywheel

Trying to work out some pesky flywheel dynamics for a project I'm working on, would love some for your assistance to better understand the underlying concepts. For a given flywheel (thin-walled ...
1
vote
0answers
91 views

Why does angular velocity lies in the axis passing through the center of the circumference?

I understand that it can't be placed anywhere on the radius because it doesn't vary with it ( and so of course it doens't make sense to place it anywhere else on the plane), but why do we place it ...
0
votes
2answers
64 views

Expected behavior of the gravity under some experiment [duplicate]

I would like to know the expected behavior of the Gravity under the following mentioned imaginary experiment: What if we dig a well or a boar or a straight hole (say, its diameter is 100 meter) ...
0
votes
1answer
2k views

How is torque equal to moment of inertia times angular acceleration divided by g?

How is the following relation true $$\tau = \large\frac{I}{g} \times \alpha$$ where $\tau$ is torque, $I$ is moment of inertia, $g= 9.8ms^{-2}$, and $\alpha=$ angular acceleration.
1
vote
1answer
381 views

Double Compound Pendulum: why use inertia about the center of mass for bottom pendulum?

I'm trying to wrap my head around the kinetic energy of a double compound pendulum, like the one shown in the Wikipedia article on double pendulums. I know for computing the kinetic energy of the ...
1
vote
1answer
588 views

Non-commutative property of rotation

Addition of angles are non-commutative in three dimensions. Hence some other angular vector quantities like angular velocity, momentum become non-commutative. What is the physical significance of this ...
0
votes
3answers
7k views

Finding Angular Acceleration of rod given radius and angle

A uniform rod is 2.0 m long. The rod is pivoted about a horizontal, frictionless pin through one end. The rod is released from rest at an angle of 30° above the horizontal. What is the angular ...
1
vote
2answers
430 views

Extracting acceleration vector from rotated aircraft

Suppose we have an aircraft with accelerometer measuring accelerations along each axis. It is mounted in a way so it is perpendicular to the plane in all axes (that should be obvious). We also have ...
4
votes
4answers
549 views

If a pendulum is on a rotating table, will a torque be generated?

Here is the set up. Very simple. A flat (i.e. horizontal table, there is no gravity) and rounded table that spins on its axis (through the center of the table). A spring mass system is now put on the ...