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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Why is inertia connected with mass and not momentum? [duplicate]

When my teacher was teaching us $E=mc^2$, he told us that the relativistic mass of an object increases when the speed increase. He told us that it is due to the increase of inertia. He said that as ...
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Thought experiment in Mach's principle - Can a void universe be considered with special relativity?

Mach's principle is based on a thought experiment in which an astronaut floats in the middle of a space devoid of all matter and all landmarks. No star, no source of energy is present, whatever the ...
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Electromagnetic Waves and Inertia

I have a conceptual question. Suppose we have two bodies of equal masses. One is electrically neutral and the other is electrically charged (positivley charged). Now we apply equal magnitude of force ...
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Would you run faster on Mars?

Given the 1/3rd of Earth's gravity on Mars and neglecting space suit limitations and also assuming you have maintained your muscle strength, would you run faster on Mars? The answer may not be so ...
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Is inertia present at the level of elementary particles?

Is a more massive elementary particle will experience more inertia in a one-on-one particle interaction?
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How to find inertia tensor of a circular ring from angular momentum and velocity?

Consider a thin circular ring with radius $R$ and axis of rotation as shown in the figure. If $\vec{L}$ denotes angular momentum and $\vec{w}$ is the angular velocity then $$\vec{L}=\begin{bmatrix} I_{...
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Are there two competing definitions of "inertia"?

The term inertia is often introduced by stating Newton's first law: An object stays at rest or moves with $\vec{v}=const.$, if the resultant force is zero. This feature of masses is called "...
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Why does "net force" being zero not mean that the parachuter becomes stationary in the atmosphere?

Take the typical phyiscs / classical mechanics example of a parachuter descending at constant speed. The two forces acting on the parachuter are weight, which has direction towards the ground, and air ...
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What happens to the acceleration from an initial force according to the law of inertia?

Say we hit a golf ball with a club. Hitting the ball requires a force = m*a. According to the law of inertia, velocity should be constant, but how can that velocity be constant if we hit the golf ball ...
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Why does the distribution of mass affect the resistance to being pushed aka inertia?

So I know that the mass of distribution of an object affects inertia. But the question I'm asking is WHY. And having fancy formulas for me is not actually answering the WHY, it just confirms it. So If ...
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Taking drag into consideration, how does mass affect horizontal range given that the impulse applied is always the same? [closed]

If two objects, one light and one heavy but otherwise identical, are given the same impulse from rest and begin to travel horizontally through a resistive fluid, which object makes it farther?
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In the Langevin dynamics: neglecting inertia. A mathematician trying to understand physics terminology

If we write the Langevin equation: for a particle with mass $m$, position $x$ and velocity $v$, with some damping coefficient $\gamma$, $$ m dV(t)=-\gamma V(t)dt+dW(t) ,~~~~~~~dX(t)=V(t)dt.$$ Then as $...
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Why are there so many fundamental differences between contact forces and gravity?

I had this very fruitful conversation about the inertial motion of charged particles on gravitational/electric fields. A field force like gravity, can't be felt, it does not produce proper ...
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Is the motion of an electron bound into an atom inertial?

When a particle moves on a gravitational potential subject to no contact and tidal forces, the particule clearly is in inertial movement. But what about the "motion" of an electron bound ...
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Equivalence principle, geodesics, and proper acceleration are exclusive to general relativity, or they can be understood in classical mechanics terms?

I have been told that "inertial movements, or distinction between proper and coordinate acceleration don't have meaning out of GR". But now I'm confused, I always though of these concepts in ...
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Which is true: objects keep spinning because of inertia, or objects keep spinning because of centripetal force?

I'm hoping any gravity or friction can be ignored. I gather a spinning object is a non-inertial frame. I suppose that's because change of direction is acceleration. Continued acceleration requires ...
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Inertial movement of a body on the surface of a planet being dragged away

When we stand still on the surface of Earth, this is clearly a non-inertial frame. Inertial frames of reference are characterized by accelerometers measuring zero, so you fell weightless when you: 1) ...
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Has anyone directly observed the equivalence of inertial and gravitational mass for the electromagnetic force?

Before someone tells me to drop a bowling ball and feather off the Leaning Tower of Pisa in a vacuum, let me point out that, in general relativity, you can't deduce anything about either mass of a ...
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Why is a larger force needed when you decrease the distance in regards of torque? [closed]

I think it's because of inertia.
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Torque and moment of inertia with bikes

Can someboby please explain to me why it is better for a bicycle/ motor cycle to have lower center of mass when it rounds a turn. What I could gather from the rule I = mr2 Was that the arm is shorter ...
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How many types of inertia are there?

I was looking for types of inertia, but I am confused. My book says there are three types of inertia, namely inertia of rest, inertia of motion, and inertia of direction. But when I searched for these ...
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Gravitational and inertial mass seem to result from different fields, yet virtually the same. How do new physics theories attempt to reconcile this?

As best I understand it, internal mass (at rest) is due to interactions of particles with the Higgs field, and in equation terms, due to various chiral terms, sometimes described as swapping chirality....
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Why can we calculate moment of inertia, but not inertia?

I'm learning about rotational motion and the moment of inertia. Unlike inertia that I learned before, there is a formula to calculate rotational inertia. I'm having trouble understanding why it's ...
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Why don't we use momentum to quantify inertia?

My understanding of Newton's 1st and 2nd laws have led me to believe that inertia and momentum are the same. 1st law: An external force is required to overcome an object's inertia 2nd law: Force is ...
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The moment of inertia of a hollow cylinder is lower than that of the "corresponding" solid cylinder (same density, outer radius, height):

This is a self-answered "question" for those scratching their heads after learning, e.g. in class, that the moment of inertia of a hollow cylinder is higher than that of solid cylinder. Note ...
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Proof behind inertia increases with mass?

My book starts off by giving an example that if we kick a football it flies away but if we kick a stone of the same size with equal force then it stays at rest. It says that from this series of events ...
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Can the inertia tensor be expressed as a diagonal matrix for any shaped object?

I'm working on analytical mechanics for a rigid rotating body and I'm a bit confused about when we're allowed to express the inertia tensor as a matrix proportional to the identity matrix ie $$\begin{...
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Red shift/Blue shift as a standard for determining absolute motion

If I begin standing, I can imagine that there are photons of various wavelengths arriving at my location from all directions. If we eliminate local energy coming from stars and radiating bodies, ...
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How to calculate the gyroscopic inertia for this exact experiment?

This question refers to the photo below. The wheel in the middle can rotate vertically without friction. The construction around it can rotate the wheel horizontally as well, also without friction. ...
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Walking pace and torque

How to understand the relationship between the mass of a person, the length of the legs and the walking pace? My professor tried to explain it but I didn't quite get it. So we can consider the hips as ...
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Water flowing after turning off pump

I'm pumping water with a mini pump through a plastic hose (1 meter), between two glass containers. My problem is that if I turn off the pump when the water is flowing through the entire hose, water ...
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An elevator moving with constant velocity

While an elevator moves up, it moves up with a constant velocity. I read this post and understood that it's because of inertia. However, I'm not really convinced. So what happens which I have ...
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Inertia of an elevator

Imagine a situation where we have a relatively light empty elevator moving up at a pretty high constant velocity say something above $10\ m/s$, just so that it has a considerable amount of momentum ...
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Does inertia imply that a cyclindrical mass in frictionless motion on a horizontal plane keeps moving forever ( with $\vec F = O$)?

Suppose I have a perfectly cylindrical pencil and set it in motion on a perfectly smooth and horizontal table, in such a way that the axis of the pencil is in translation. Is the state of this object ,...
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Moment of inertia of the water flowing through a freely-rotating cylinder

I want to model the kinematics behind a mid-air bottle-flip, in order to find the probability of the bottle-flip being successful given initial conditions. This is for my high-school mathematics ...
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The impact of mass distribution on time taken for a cylinder to roll down a ramp

I am carrying out an experiment to test out the impact of mass distribution on time taken for a cylinder to roll down a ramp. I have kept the overall mass of the cylinder constant, as well as the ...
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Is pseudo force another form of inertia observed from accelerating frame of reference?

We know that pseudo forces act when we opt for non-inertial frames of reference. Is pseudo force another form of inertia observed from accelerating frame of reference?
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In the context of General Relativity, does having gravitational mass imply resistance to acceleration?

My question is essentially this one, but since that one never got a satisfactory answer, and it's of such fundamental concern, I'd like to try asking it in a different way. The question is whether ...
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Newton first law of motion

The State of rest and the state of uniform linear motion are equivalent. Why?
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Does time causes inertia? [closed]

As you know inertia is an behaviour of matter that objects resist change in their motion. If an object is at rest it will remain at rest and if an object is moving with a constant velocity it will ...
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Photon follows law of inertia? [closed]

Is the law of inertia compatible with quantum mechanics? If yes, how? And if a particle is both present and absent at the same time, (the uncertainty principle: stating that when an electron is on ...
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Decrease of the rotation speed of a wheel with inertia, when we stop applying rotational force to it [closed]

Let's say we have a wheel rotating at a constant speed $s$. Suddenly at time $t=1$ we stop applying force to it. What is the law for the decrease of the speed, until it stops? I guess it will look ...
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Forces on us on a rotating Earth

So the earth is constantly rotating but it doesn't need a force to rotate. It'll rotate indefinitely.(?) But we and other masses on earth need a force on us to continue rotating along with earth? And ...
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An object on top of a rotating mass like earth

Why do objects fall down in same place on the rotating earth? I get that newton's first law is the reason an object falling on a high speed train will maintain the same velocity as a train and ...
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When a car accelerates relative to earth, why can't we say earth accelerates relative to car?

When a car moves away from a standstill, why do we say that the car has accelerated? Isn't it equally correct to say that the earth has accelerated in the reference frame of the car? What breaks the ...
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Very strange published papers on Mach's Principle

I have recently come across a set of peer-reviewed conference papers (https://petermarkjansson.com/research/machs-principle/) reporting observations of electromagnetic markers of Mach's Principle. In ...
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How to calculate HP knowing flywheel weight

So I've seen a guy on Youtube that has an RC nitro engine. He attached a quite big flywheel of known weight to its output, and then by measuring the time that it takes to reach max rpm he was able to ...
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How is Newton's first law of motion different from Galileo's law of inertia? If the two are the same, then why is the first law named after Newton?

Galileo's law of inertia (at least what I've learned) is "A body moving with constant velocity will continue to move in this path in the absence of external forces". And Newton's first law ...
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In a non-inertial reference frame can an object have zero inertia? [closed]

Can an object in a non-inertial reference frame have zero or NO inertia?
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Moment of inertia of a rotating square toroid [closed]

I'm trying to work out the moment of inertia (i.e. what would be $I=mr^2$ for a point mass) of the volume of rotation around the y-axis of a square with side length a, at a radius along the x-axis R, ...
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