Inertial Mass and Inertia

[flano]

whats the difference between these terms?

[jake-the-peg]

Inertia is the property of a body such that it tends to keep moving in a straight line unless forced to change.

Inertial mass is in a sense the amount of matter in a system with that property.

Because F=ma you can say it's the ratio of force you need to apply to a body to get a certain acceleration.

Note that Gravitational mass is due to another property of matter, that is it's tendency to attract other matter.

The Gravitational constant G is defined in such a way that in most applications we can consider Gravitation mass to be equivilent to inertial mass even though these are two quite distinct properties of matter

[Clanad]

Simply put, one defines the other... Inertial mass is a measure of an object's inertia: its resistance to changing its state of motion when a force is applied. An object with small inertial mass changes its motion more readily, and an object with large inertial mass does so less readily... (Source, Linear Motions Systems)

[Clanad]

Hmmm... Synchronocity at work again...