# Tagged Questions

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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### Moment of Inertia of a Motion Simulator Frame

I have a rather specific question. I'm trying to build a motion simulator for flight and racing sims, similar to this: https://www.youtube.com/watch?v=JQAZB3EnI_w . The basic concept is a platform ...
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### Law of inertia, Frames of reference

Ok, we all know that an Inertial frame of reference is defined like this: "An inertial frame of reference is one frame where Newton's First Law holds, therefore, a body has a constant velocity or ...
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### Htting the brakes with a pickup truck full of water

I am looking to settle a bet. My friend and I were discussing truck bed pools, which are pick-up trucks with their beds tarped and filled with water converting them into small temporary swimming pools....
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### Can an object spinning near the speed of light be accelerated significantly in any direction?

This question made me curious. It refers to a ball which is rotating so that its equator is approaching the speed of light, then talks about what it would look like if the observer moved. What I'm ...
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### Does a rotating object have more inertia, mass and gravitational pull?

When an object is rotating on an axis, it has stored rotational energy in it. Since energy and mass are related, does this stored rotation increase the mass of the object? And if so, will it be harder ...
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### Can we catch a bullet in a gun barrel? If not, why not?

I have looked through various questions about guns and bullets but I haven't found this one. If someone fires a handgun there is a recoil. Shooters learn to control this, the gun does not fly out of ...
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### Inertia on relativistic mass when particle is near speed of light

Inertia is directly proportional to mass but what happens when something travel to speed near to light. Its relativistic mass tends to infinity but that is false mass so I want to know if inertia is ...
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### How is inertia related to friction?

Inertia is the tendency for moving object to continue to move at constant velocity. My book says "in order to initiate motion in an object, inertia must be overcome to start the movement." But that ...
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### Is it experimentally verified that the neutrinos are affected by gravity?

If neutrinos (or any other particles) wasn't affected by gravity that would contradict the general theory of relativity. I'm convinced that the postulate of the equivalence between inertial mass and ...
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### What is inertia of a body?

The definition of inertia is "Inertia is the resistance offered by the body whenever its state of motion is changed." What is inertia of a body? Is inertia actually a force exerted by the body? If ...
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### Warship cannons influence on speed/direction [closed]

I've been looking at great warships like the Iowa or equivalent ww2 warships, and I raised question. This kind of war is pretty much only about strategic placements, accuracy and fire power. Hence ...
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### Are Fluted Barrels More Rigid Than Standard Ones?

This seems to be quite a debated topic in the shooting community and is something I'm not sure about. A fluted barrel is a barrel that has grooves milled into it to reduce weight, help it cool faster ...
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### Clarification on inertial mass

I was talking to my friend the other day about the origin of inertia and it pondered both of our brains. I would like to know if the concept of inertia exists at the quantum level? I realize that ...
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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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### How does a wheelie work?

So I've been trying to create a mathematical model for an electric motorcycle and began to wonder about the maximum possible torque that could be supplied to the rear driven wheel without having the ...
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### Does a truck stop faster if the stack on the back of truck is stable or if it moves forward?

My question in the title might not be very descriptive so I am re-writing it here: If there is a truck in motion and it has stack of hay (lets suppose) on the back. Now if the truck comes to a sudden ...
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### Inertia Vs Momentum

At my recent lesson on kinematics, my teacher taught about inertia and momentum. This is what she said. Inertia: a characteristic of an object that resists changes to its state of motion. Momentum: ...
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### Physics behind this drunken ball

I am trying to understand the physics behind this drunken ball: There is a wight inside the ball as he mentions, but where, at what position ? http://www.grand-illusions.com/acatalog/Drunken-Ball-...
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### What exactly is the mass of a body? What determines it?

The term "mass" is very common. But what does it depend on? How is it known?
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### If a vehicle (bus, train) rapidly stops (or accelerates, or turns), why don't our hair or clothes move from the inertial force?

Many times I was sitting in a train, watching closely nearby people. If the vehicle changes it's movement rapidly (brakes, turns, etc), then obviously, people feel the inertial pseudo-force that ...
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### Help me with inertia [closed]

An example of inertia in action is trying to slow down to a complete stop after running a race . what could you do in this situation to increase your inertia? would this help you slow down more ...
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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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### What does it signify that electrostatic mass cannot exist without inertial mass?

From Coulomb's law and Newton's second law we can state that if there is electrostatic mass (charge) at any point of space then there has to exist inertial mass also at that point of space. Otherwise, ...
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### Do objects launched from Earth retain the Earth's lateral inertia (67,000mph)

We've probably all heard of the gun on a train theory. Fire a bullet that would normally travel 500mph on a train that's moving 200mph (in the same direction the train is moving) and you've now got a ...
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### Could a really tall tube suck garbage in to space?

When I was around 10 years old, I had this idea that was supposed to solve our waste problems; I imagined having tubes miles high that would stretch in to space. Every tube would have a door at the ...
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### Why is the Earth self-rotating? [duplicate]

What drives this happen? Would it be the internal energy or by an external force? I did try to Google the answer, but could not find a good one.
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### Parallel axis theorem

For this question we are working in 2-D space. Let's say that we have an arbitrary body. I know the inertia with respect to a perpendicular axis (to the body, that is) that passes through a point (A). ...
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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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### What role does inertia play in determining how long an egg rotates?

There are two identical eggs boiled egg and raw egg, both are rotated with same angular speed. Which one will come to rest earlier? I have read this question, but it discuss more about friction 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 ...
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### What really is “inertial force”?

In Fluid Mechanics we often see the term inertial force when discussing Reynolds number. The problem is, I didn't really get what's this inertial force. Basically, the notion of inertia I have is that ...
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### How to account for inertia in kinematics?

Alright, I'm only in AP Physics and I asked my teacher and he couldn't help me... I'm making a 2D physics engine and I'm having problems when it comes to gravity between objects and I think its ...
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### Can we explain Newton's first law mathematically?

At constant speed there is no acceleration. $(f'(x)=v'=0=a)$ .If $a=0$ then $F=ma=0$ and therefore no force acts on the object so the object will continue in the same direction, if any. This is only ...
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### Have you ever seen in your car a mosquito? it's not capable of going 60 mph. How come it can still keep up with the car as if it weren't trying [duplicate]

For instance, a fly is staying at the same spot, then your car suddenly moves forward at a rate of 60 mph. The mosquito IS staying at the same spot but for some reason it moves along with the car as ...
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### How does electron spin change instantaneously without violating inertia principle?

The inertia in one of the main properties of matter. That is why all process in macro world do not happen instantaneously. What I do not understand is how we should apply this general idea of inertia ...
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### What is the definition of inertial mass?

What is the definition of inertial mass? I can see two options, either it's the coefficient associated with the object being accelerated in Newton's 2nd Law, or it's the coefficient relating momentum ...
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### Newton's first law: is his concept of (force of ) inertia still useful and used?

The force of inertia is the property common to all bodies that remain in their state, either at rest or in motion, unless some external cause is introduced to make them alter this state. That is ...
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### Will I be able to push a small object in front of me in the outer space?

Imagine I am standing on Earth, and pushing a tennis ball away from me. The ball moves. If it is very heavy, I will move back instead of the ball. Now consider the same scenario in outer space, where ...
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### Researching an automobile accident.Wondering if someone can help me as I never studied physics [closed]

I am trying do some independent research on a recent auto collision where the information released doesn't seem plausible based on the pictures that I have seen of the accidents aftermath. A 5,500lb(...
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### Alcubierre drive and inertia.

What is the inertia or velocity of a vehicle upon exiting or shutting down an Alcubierre bubble? Would the vehicle maintain the velocity it had in the bubble? I'm not sure I asked the question in a ...
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### Inertia and momentum

Question #1: Why does speed have nothing to do with inertia? Question #2: If a car hits a steel wall and stops, where did the momentum go?
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### Is inertia actually a property of the force rather than the mass?

I ask this because it occurred to me that the inertial property of mass only actually arises in the context of forces (such as the EM force) as a resistance to their accelerating effect. Inertia plays ...
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### Equilibrium: Inertia & Applied Force

Thank you for taking the time to read this. I am lay and will understand if the question is closed. My understanding is that in a vacuum, a constant force of $n$ applied to an object of mass $m$, ...
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### Gravity vs inertia

As stated according to Newton laws of gravity, every object with mass attracts all other object with a force which produces acceleration. Basically there are several forces in the universe which ...
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### Do lawn mowers still cut the grasses if they aren't attached to the ground?

A rotary lawn mower cuts the grasses by rotating it's sharp blade on it but if the grasses aren't attached to the ground will they still cut them? What forces act on this system? I know the answer is ...
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### Electromagnetic factors affecting inertial mass of a body affect its gravitational mass or not?

We can see that when a charge sphere is at rest & we are to put it in motion with any desired velocity than we will have to apply the same force for a longer time as if it were applied to the ...
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### Work done or not in this case?

I have a very simple question. A motorboat directed upstream is seen to be at rest from the bank of a river. Is the engine doing any work? Is it right to say that since it is not causing any ...
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### What determines the speed required to pull a table cloth?

I was watching this show "Street Genius" on National Geographic and the host Tim Shaw demonstrated an experiment about Inertia, What he did was, He tied one end of a table cloth to a car through a ...
The unit for angular acceleration $\alpha$ is: $$\mathrm{rad/s^2}$$ The unit for torque is $\mathrm{Nm}$: $$\mathrm{kg\ m^2/s^2}$$ And their relationship with Inertia is: $$I = \tau/\alpha$$ So ...