# 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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### 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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### Why do objects have inertia? [duplicate]

I was going through the chapter of "Newton's Laws of Motion", where I was introduced to the concept of inertia in Newton's First Law. I saw that all objects that have mass will have ...
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### Are falling objects harder to push compared to objects at rest

While an object is still in the air falling under the influence of gravity, does it take greater force to push or steer it to the side compared to when the object is in a state of rest?
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### How to calculate heat loss of a building using thermal inertia

I need to calculate the amount of heat that is lost in an hour. I know the temperature of the building the (effective) temperature of the outside and the thermal inertia of the building. The building ...
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### Reason behind Inertia

Has any physicist work on the reason behind Inertia? Why do we have inertia only during acceleration? No inertia during constant velocity.
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### Is inertia the same as centrifugal force?

My cousin told me that inertia is just a pseudo force that act on a thing, because he said that inertia is the same as centrifugal force. But when I search for the true fact in Google, I found that ...
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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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### How do you apply each of Newton's laws to specific scenarios?

The 3 Newton's laws of motion are easy to be understood but examples citing which law caused it are so confusing - say a bullet fired from a gun - many people state it cause is 3rd Law - but I see all ...
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### Confusion about an example of inertia related to bus

When the bus is stationary the passengers are also stationary. When the bus starts moving the part of the body (lower part) in contact with bus starts moving, but due to inertia the upper part remains ...
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### Why lighter bottles stay on better rather than heavy bottles?

I was watching a Mythbusters video of them doing the table cloth trick and Adam says that the lighter bottle worked better. Don't heavy bottles (more mass) have more inertia and therefore should work ...
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### Working principle of an accelerometer

I'm trying to confirm my concepts regarding inertia and accelerometers. Need to verify / correct my thoughts, which are as follows: Inertia is the property of matter to resist a change in its state ...
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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 ...
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### Why can't we measure inertia? what are the applications of inertia?

why there is less importance for 'inertia' in school studies...does the concept of inertia is least significant nowadays? is inertia a measurable quantity? Is there any application of inertia?
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### Why is Newton's First Law not considered a vacuous statement? [duplicate]

How did Newton come to postulate the law of inertia when every inertial body that he was considering was (by his own other hypotheses) being acted on by the force of universal gravitation. In other ...
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### Moment of Inertia using centre of mass knowing distance and weight of rod [closed]

I know the mass, I know the center of gravity position. Can i use this to work out the moment of inertia of a rod. So my ruler is 30 cm long and I know its mass to be 11.8g I have some blu tac which ...
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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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### “Mass is a measure of an object’s ability to resist motion or movement of any kind”

This statement is presented as wrong, but I dont understand why. Specifically, what is the diff between motion and "movement of any kind"? Its to do with a question about inertia. I understand that ...
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### How can energy have inertia?

How can energy have inertia? To my intuition, inertia is so closely associated with mass that my intuition says "Huh?" Indirectly by mass energy equivalence it works fine, for example: I have a ...
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### Inertia and related quantities

I wanted to know what is a frame of inertai? Specifically, what does it mean by a frame? I know that inertia is the restistance to motion of a mass, a larger mass resists motion more than a smaller ...
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### Definition of mass

In high school physics, I was taught that mass was just how much "stuff" or matter there is in an object. However, now that I am learning physics again in college, I am taught that mass of an object (...
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### An expanding, sliding charged tube's self-imposed electromagnetic induction

If I have a simple cylindrical electrically-insulating tube possessing a net electrostatic charge and allow the tube to slide parallel to the tube's axis, that tube will possess electric currents ...
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### Mass as worldline tension?

In Special Relativity, the equation of motion of a particle of proper mass $m$ is \begin{equation}\tag{1} \frac{d p^a}{d \tau} = \mathfrak{F}^a, \end{equation} where $p^a = m \, u^a$ is the 4-momentum,...
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### Calculating end position from existing position, velocity, deceleration and time

I am writing a piece of software where the user can drag an element only on the x axis. When the user lets go of the drag while the item is in motion I can determine the x velocity and the current x ...
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### Why does inertia happen?

In this video R P Feynman relates a story where his father told him that, even though we know the word "inertia" and what it means, nobody knows why inertia happens. Is that still true?
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### Why won't a full laundry basket bounce?

I've noticed a curious behavior of my plastic hamper and laundry baskets. When they are empty tossing them more then a few feet from hip height (3 feet) causes them to bounce and tumble. Yet when they ...
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### If the aircraft has no inertia, how will it move after losing power?

If the aircraft has no inertia, how will it move after losing power? I think because of the aerodynamic force, the aircraft stopped moving immediately. Am I right?
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### Why doesn't a test charge placed in an electric field, trace out the same path as the electric field lines?

Consider for example a positive charge placed between a positive charge and a negative charge. Initially the test charge is placed closer to positive charge. Why is path followed by the test charge ...
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### What is the cause of motion in geodesic

The shortest or longest path in curved space between two points is geodesic . What about a body having no potential energy was put in geodesic near earth , what makes it move , May be it is about the ...
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### Calculating new mass moments given change in CG and transformation

Given the mass moments of inertia about the CG of the body pre-rotation, and the new CG & rotation matrix1, how can I find the new mass moments about the body's new CG? My CGs are described as ...
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### Should the coin be heavier or lighter in the coin drop experiment?

The Coin Drop experiment is a classic experiment used to demonstrate Newton's First Law of Motion. In this experiment, a glass is covered with a card and a coin is place on the card. The card is given ...
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### General relativity (gravitoelectromagnetism) and the origin of inertia

On this website describing Gravity Probe B and its importance the author(s) end with this quote and discussion: Pfister sums up current thinking this way in Mach's Principle: From Newton's Bucket ...
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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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### Can momentum be considered as a measure of inertia of motion?

If inertia of motion is a body's tendency to be in motion then can momentum be considered as a measure to calculate that tendency to be in motion?
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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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### How to calculate the tensor of inertia in this problem?

I have the following geometry for my problem: I'm asked to calculate the tensor of Inertia: \$\stackrel{\leftrightarrow}{I}_{O}=\left[\begin{array}{ccc}{I_{11}} & {-P_{12}} & {-P_{13}} \\ {-...
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### What happens when the matter is not showing the property of inertia? [closed]

I am trying to imagine a situation when there is no inertia.
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### How may the situation, when there is no inertia? [duplicate]

I want to know clearly the real concept of inertia.I have seen lot of definitions regarding inertia.But I could not exactly find real meaning of inertia.
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### Will anyone please explain this problem using 4 fundamental forces?

If there are only four fundamental forces (gravity,e.m.,strong,weak) in the universe and all other forces can be expressed as a function of them then consider this problem. Suppose I throw a particle '...
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### Why is it impossible to start or stop an object instantaneously? In what ways can a non-accelerating object move? [closed]

Why is it impossible to start or stop an object instantaneously? In what ways can a non-accelerating object move? I think this has to do something with inertia, but I am not exactly sure I fully ...
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### Why does a ball bounce?

If an object is acted on by equal and opposite forces then it will be in equilibrium, and it's acceleration or velocity (and so direction as well) will not be changed. So when a ball bounces, it ...
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### Why do we feel resistance to gravity rather than the acceleration of gravity?

What's the reason it behaves differently from all other forces? What I mean is, if you're in orbit you're accelerating toward the earth at almost 9.8m/s^2, but you feel nothing. If you are riding a ...
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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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### Why are you accelerating yet remaining at a constant speed while going around a curve? [duplicate]

We have to write a rap in physics, and it has to answer a prompt he gave us on this packet. The prompt for the verse I am writing is: Pretend you are driving a car on the freeway going 65 mph. The ...
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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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### Why does things travel in a straight line in inertial frames?

Why does physical entities travel in straight paths in a flat space-time and in geodesic in curved spacetime? Is it due to Inertia? If it is, then why does waves also follow the same pattern?
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### Isn't inertia experience by person in moving bus is 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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### What causes a rotating object to rotate forever without external force—inertia, or something else?

Someone told me that it is not inertia, but I think it is inertia, because it will rotate forever. In my understanding, inertia is the constant motion of an object without external force. Am I wrong?
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### Do electromagnetic fields have inertia? Or, what sets the speed of light?

In all mechanical waves, there is a restoring force and an inertial influence. For example, a plucked string oscillates because the restoring force brings it back to being straight and then the string'...