what exactly is inertia?

Answer 1

Inertia is the property of an object to remain at constant velocity unless acted upon by an outside force. The principle of inertia is one of the fundamental principles of classical physics which are used to describe the motion of matter and how it is affected by applied forces. Today, it is most commonly defined using Sir Isaac Newton's First Law of Motion, which states:

Every body perseveres in its state of being at rest or of moving uniformly straight ahead, except insofar as it is compelled to change its state by forces impressed. [Cohen & Whitman 1999 translation]

The description of inertia presented by Newton's law is still considered the standard for classical physics. However, it has also been refined and expanded over time to reflect developments in understanding of relativity and quantum physics which have led to somewhat different (and more mathematical) interpretations in some of those fields.

It should be emphasized that 'inertia' is a scientific principle, and thus not quantifiable. Therefore, contrary to popular belief, it is neither a force nor a measure of mass. In common usage, however, people may also use the term "inertia" to refer to an object's "amount of resistance to change in velocity" (which is quantified by its mass), and sometimes its momentum, depending on context (e.g. "this object has a lot of inertia"). The term "inertia" is more properly understood as a shorthand for "the principle of inertia as described by Newton in his First Law."

In simple terms we can say that "In an isolated system, a body at rest will remain at rest and a body moving with constant velocity will continue to do so, unless disturbed by an unbalanced force"

Answer 2

Inertia is the idea that an object keeps moving unless acted upon by an outside force. Much of the initial work written about inertia was done by Isaac Newton in the 17th century and became known as his first law of physics. It is one of the basic principles of physics and has a number of real-life applications, as it helps to explain much of why objects behave the way they do.

The idea of inertia is quite simple. Inertia is the principle that is that an object will tend to keep moving at a certain speed and direction unless something else acts to change it. That external force could be almost anything. Friction is a common external force that can change the speed and direction of a moving object. Many other objects can also affect motion, however, from gravity of the earth's pull to another person. The key idea is that an object will keep moving (or stay still) unless something else influences it otherwise.

Inertia helps to justify why many objects act in certain ways. For example, inertia is a reason why a ball that is thrown up in the air doesn't keep flying forever. It helps to explain why brakes use friction to help slow down a bike, or why an apple falling from a tree is stopped when it hits the ground. Without inertia, the world would be quite different. The principle of inertia touches a surprising number of aspects of daily life that few ever consider.

While the principle of inertia sounds relatively simple, its application in everyday life can be much more complex. Many aspects of inertia are studied and considered by physicists, engineers and product designers. Principles of inertia are used in many different fields where motion, speed and directional control are important factors.

The inertia principle is a basic and fundamental concept in physics. The basic concept of inertia that an object will keep moving until influenced otherwise is a key reason why many everyday objects behave in certain ways. It also helps justify why many products are designed the way they do.

Answer 3

The previous answers covered only one aspect of inertia. The inertial mass of an object determines how much it accelerates when a given force is applied to it, by Newton's famous F = ma relationship.

To the best of our measurements, inertial mass equals gravitational mass for all known objects. Otherwise, an object with a higher gravitational than inertial mass would fall faster. As we learn more about gravity, we may find a reason for this. Meanwhile, it's just a phenomenal coincidence!

Answer 4

Inertia is inability of body to change the state of rest or uniform motion. It depends on mass of the body. heavier body has more inertia. So that heavy trucks have low speed limit/restriction on high ways as they cant stop suddenly
(because of large mass) and have more chance of accident

Answer 5

inertia is the natural tendency of an object to remain in a state of rest or in a state uniform motion in a straight line unless it is compelled to change that state by an external unbalanced force.

Answer 6

All objects resist being pushed around, even if there is little or no friction. Once an object is moving, it takes an equivalent amount of effort to stop it, i.e., to change that state of motion. This is a principle called inertia.

More scientifically, inertia is the principle that an object will maintain its state of motion until acted upon by unbalanced forces, i.e. two or more forces that push against the object in such a way that they do not balance out. Of course, if the forces balance out, the object is not going to change where it is currently going.

An example of balanced forces is when you are sitting inside a car that is traveling at a constant speed along a flat piece of road. The only forces acting on you at that point is the Earth pulling you down onto the seat and the seat pushing up against you. Relative to the Earth, you maintain your motion for as long as the car does not accelerate or decelerate.

Mach's Principle and Einstein's Geodesics

An interesting point about inertia is that nobody is quite sure what its origin is. We take it for granted that it's a property of objects with mass, but how does an object 'know' how it is moving, so that it can resist efforts to change that movement? Both Galileo and Newton thought that an object somehow 'knows' its movement relative to distant matter. In 1863, Ernest Mach published "Die Machanik" in which he formalized this argument of his forerunners. Einstein was greatly influenced by it. In 1918 he named it "Mach's Principle".

Einstein's general relativity took the definition of inertia a step further by showing that all objects move through a continuum called 'spacetime' along spacetime geodesics. This simply means that objects take the path of least action (effort) through spacetime, unless acted upon by forces. The matter of the Universe defines the gravitational field and the gravitational field defines the geodesic paths through spacetime.

The present scientific view is that the distant galaxies emitted virtual gravitons that traveled through space for billions of years before being absorbed by your body as you're sitting in the car. The resistance of your body to acceleration is wholly or partially due to the interaction between your body and virtual gravitons that were originally emitted billions of years ago by 'living' and long 'dead' stars in distant galaxies. Is that weird, or what?

Time-stress the Origin of Inertia?

Presently there is another view that is slightly controversial, but far less weird. It says that when you move freely in empty space, the various parts of your body all record time at the same rate. A scientist would say that 'the temporal (time) relations' between all parts of your body remain constant, or that there is no 'temporal stress' on your body.

As soon as you are being accelerated, the temporal relations are disturbed and the various parts of your body need to run at their own times. This creates temporal stress inside the body and the body's reaction is to resist this disturbance so that the stress is reduced; hence it shows inertia – it wants to follow its spacetime geodesic with the minimum effort and stress.

The beauty of this hypothesis is that it only requires Einstein's rather easy to understand special theory of relativity and not the quite formidable general theory of relativity. Special relativity is mostly about how relative movement influences relative time.

Answer 7

inertia is the tendency of a body/system to remain in the state of motion [ either at rest or moving} and resist its change in existing state. for eg if u are standing in a moving bus ur feet Are in motion in accordance to buses motion bot Ur torso remains still. when the bus stops ur feet were supposed to be in a state of motion so the resist and ur torso seems to fall ahead accordingly...

Answer 8

INERTIA IS;

The inability of body to change it's state of rest or uniform motion ,without the help of an external force.....

OR

The tendency of a body to resist acceleration....

OR

Resistance or disinclination to motion...

OR

the tendency of an object to resist changes in its velocity....

Answer 9

This is first law of motion by Newton. It says "the tendency of a body not to undergo any change in its state of motion unless it is acted upon by a external imbalance force". I hope you are aware of other two laws of motion by Newton.

Answer 10

simply it is a resistance to the motion of a body weather it is in rest or in uniform motion