# Questions tagged [inertia]

Inertia is the tendency of a body to oppose changes to its state of motion. DO NOT USE THIS TAG for moment-of-inertia!

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### Where this relation for general non rigid motion comes from?

In Goldstein's Classical Mechanics book in the chapter about the dynamics of rigid bodies the equation $$\dfrac{dL_i}{dt}+\epsilon_{ijk}\omega_jL_k = N_i$$ is presented. Now, in one exercise, we are ...
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### How should one determine the motion of extremely large extended objects?

[To put this question in context, I was reading "How much time will it take to move an object whose length is equal to one light year?" and don't really feel satisfied by the answer that has been ...
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### Closed-form equation for orientation and angular velocity over time

If a rigid body, rotating freely in 3d, experiences no friction or other external forces and has an initially diagonal inertia matrix $\mathbf{I}_0$ (with $I_{11}>I_{22}>I_{33}>0$) and ...
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### Equation for a falling coin tower

I'm referring to the following experiment- https://www.stevespanglerscience.com/lab/experiments/coin-tower/ For a given mass of identical coins stacked upon the other, and a given impulse with which ...
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### Relation between Fisher Information Matrix and Inertia Matrix

I have been wondering whether there is a relation between the Fisher Information Matrix in a stochastic particle system and Inertia Matrix?
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### What is “Radiation damping stronger than inertia.”

I'm reading a paper on creating gamma rays in a lab and I've come across a phrase I simply don't understand; "Radiation Damping Stronger Than Inertia". As I understand it radiation damping is just ...
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### The relation between mass, inertia and energy

I have trouble understanding the following concept: I learnt that mass is a measure of inertia, and that seemed logical enough. Yet separately I learnt that mass is a form of condensed energy. If ...
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### How do I convert cardinal axis inertias to an arbitrary axis inertia?

I've tried to reduce this problem to the most basic form. I know the equation for a spring-mass system is generally: $$F_{\mbox{applied}} = kx + m\ddot{x} \\$$ but, in my case, I have a spring ...
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### Avoiding inertial affects by accelerating larger mass in 2 body system

Suppose two bodies S and L are in proximity (asteroids say). L is substantially larger than S. For simplicity, let them initially have negligible angular and linear velocity. S will begin to fall ...
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### Influences on wavefunction path analysis

I was looking at simulations of a wave going through a slit. When the wavelength was much smaller than the slit width, the wave went through the slit and kept going straight like a laser beam. But ...
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### A trio of spinning marbles

My little brother showed me this devised act in which he stuck three marbles in a triangular pattern When he spun any of those marbles, the triplet would first rotate normally, but moments later, ...
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### How does an atom's electric field overcome an electron's inertia?

An electron has mass, and therefore has inertia. How does an atom's electric field perpetually overcome an electron's inertia, necessary to hold it in its shell? Does this require continual work to be ...
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### What is static mass increase effect predicted by General relativity?

According to wikipedia, static mass increase is predicted by Einstein's General Relativity. In the book 'The Meaning of Relativity' by Einstein, inertia will increase when the object is near a ...
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### Calculate Rotational Intertia

If a can of soup, and a can of beans (tightly packed), are set in a race down a rough hill (has friction), the soup wins, because the inside of the can (soup) is not drawing energy from the system. ...
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### Inertia as a fundamental interaction

Why is Inertia not included as one of the fundamental interactions, yet gravity is included as one of the four known interactions, and there is an equivalence established between gravity and inertia.
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### What do we mean by straight line in Inertia Law, autoparallel curve or extremal line?

As usually stated: Newton’s first law states that, if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed ...
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### Weight and Inertia (are they related?)

R. Feynman wrote in his lecture (The Feynman Lectures on Physics: Chapter-9) "Weight and inertia are proportional, and on the earth’s surface are often taken to be numerically equal, which causes a ...
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### Looking for ways to transform time-series data recorded from object movement into equation describing the movement direction of the object

Looking for some time-series data transformation advice! I want to know what's the best way to transform data of 9-tuples time series data of IMU (Inertia Measurement Unit) sensor, recorded from a ...
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### Isn't inertia experience by person in moving bus same as torque

When a bus moves suddenly, the person standing in it tilts backwards. This concept is explained using inertia(tendency of body to resist change in its state of motion) but when the bus moves suddenly, ...
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### How does the inertia of granules within a rotating cylinder affect its inertia?

If a cylinder is partially filled with granules and is rolling down an inclined plane, is there any relationship between the rotational motion of the granules and the motion of the cylinder? I'm ...
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### Calculating inertia of motor

I'm currently working on a project, and for futher calculations down the road (the controller of the mechanical system) I need to calculate, as accurately as possible the interia of the system. I'm ...
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### Calculate stroke force and angle for a ball rolling on a surface to reach a destination position (optimal golf putt)

I'm trying to find an algorithm which calculates the optimal golf putt (angle, force) given a 3D surface (obtained through Poisson reconstruction), start and destination position (hole). I guess that ...
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### Transfer of momentum from a wave to it’s waveguide based on theta and the inertia of the wave?

Bit of a complicated one - I've been trying to understand how the energy in a wave dissipates or transfers it's energy to the walls of a wave guide as the angle of the wave guide changes. As the ...
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### Calculating weight needed for a fixed pole

Imagine a game of swing ball, where the rope is 1m long, and the ball weighs 1kg. How do you calculate the weight that the pole has to be so it does not get pulled over, assuming it is not burried in ...
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### What's the seconde moment of a T beam with a heel?

the seconde moment of area of a rectangle is Iy = (bh^3)/12 b : base h : height What is the second moment of area of a T beam like this one ?
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### Does buoyant force become less effective as acceleration increases?

Lets say a balloon with a certain amount of buoyant lift has a 2 kg mass strapped to it (including engines) and accelerates enough that it perceives a positive 2.5 g inertial force (2.5g * weight) ...
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### Will variable but symmetrical density spheres which are otherwise identical swing at the same rate?

If you have a pendulum with the same length and different spheres on the end will the period be the same if the only variation is the distribution of mass from the center of the sphere? This is to ...
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### If inertial mass were equal to for example half of gravitational mass why would things not still fall at same rate?

I have read that it is the equality of inertial and gravitational mass that causes all objects to fall at the same rate irrespective of size. But if this were not true, what effect would we see? Would ...
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### Doubts About Force and Inertia!

But then what does inertia mean at all!? Cant we calculate how much it resists the applied force? I mean considering an imaginary plane with no friction but gravity as of Earth and an enormous mass of ...
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### Angular velocity of disc from induced motion

I came across a question regarding linear momentum $L$ and it's conservation, however I tried and got confused. It reads: A $40kg$ girl stands on the very edge of a rotating disc of mass $50kg$ and ...
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### inertial pressure on in a rotating syringe

First question on stackexchange. Hopefully somebody can help me out. I'm struggling to express the following eloquently. I have a rotating syringe tipped with a needle. rotation speed w, with radius ...