# What is inertia?

• (noun): (physics) the tendency of a body to maintain is state of rest or uniform motion unless acted upon by an external force.
See also — Additional definitions below

## Inertia

Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. 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. Inertia comes from the Latin word, iners, meaning idle, or lazy. Isaac Newton defined inertia as his first law in his Philosophiæ Naturalis Principia Mathematica, which states:

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### Some articles on inertia:

True Polar Wander
... In a stable state, the largest moments of inertia axis is aligned with the spin axis, with the smaller two moment of inertia axes lying in the plane of the equator ... body to realign the largest moment of inertia axis with the spin axis ...
Stress-strain Index - History and Relation To Moments of Inertia
... over the information provided by calculating the area moments of inertia and polar moments of inertia ...
Rotational Inertia
... Another form of inertia is rotational inertia (→ moment of inertia), which refers to the fact that a rotating rigid body maintains its state of uniform rotational motion ... Rotational inertia depends on the object remaining structurally intact as a rigid body, and also has practical consequences For example, a gyroscope uses the ...
Morison Equation - Description
... The Morison equation is the sum of two force components an inertia force in phase with the local flow acceleration and a drag force proportional to the (signed) square of the instantaneous flow ... The inertia force is of the functional form as found in potential flow theory, while the drag force has the form as found for a body placed in a steady flow ... Johnson and Schaaf these two force components, inertia and drag, are simply added to describe the force in an oscillatory flow ...
List Of Area Moments Of Inertia
... The following is a list of area moments of inertia ... The area moment of inertia or second moment of area has a unit of dimension length4, and should not be confused with the mass moment of inertia ... If the piece is thin, however, the mass moment of inertia equals the areal density times the area moment of inertia ...

### More definitions of "inertia":

• (noun): A disposition to remain inactive or inert.
Example: "He had to overcome his inertia and get back to work"
Synonyms: inactiveness, inactivity

### Famous quotes containing the word inertia:

What is wrong with priests and popes is that instead of being apostles and saints, they are nothing but empirics who say “I know” instead of “I am learning,” and pray for credulity and inertia as wise men pray for scepticism and activity.
George Bernard Shaw (1856–1950)