[/quote]jim_mich wrote: inertia - noun
[1] (physics) the tendency of matter to remain at rest if at rest, or, if moving, to keep moving in the same direction, unless affected by some outside force
[2] a tendency to remain in a fixed condition without change; disinclination to move or act
friction - noun
[1] a rubbing, esp. of one object against another
[2] disagreement or conflict because of differences of opinion, temperament, etc.
[3] (mechanics) the resistance to motion of two moving objects or surfaces that touch
momentum - noun
[1] the impetus of a moving object
[2] strength or force that keeps growing ⇒ "a campaign that gained momentum"
[3] (physics, mechanics) the product of the mass of a particle, body, etc. and its velocity (abbrev. M)
For the uneducated unstarched fops, inertia is a scalar quantity, momentum is a vector quantity (mathematical cross product of mass and velocity that also includes direction).
Note that inertia is not defined as a force. Inertia is only the resistance to change in direction or speed. Inertia does not become zero when an object is at rest where momentum can be zero relative to the observer.
This exactly explains why Randall's motion theories are unworkable as per his adored fairy physics, a mass allowed to extend in an unpowered rotating wheel performs work due to inertia that adds energy to the system. Masses do not spontaneously gain energy traveling in straight lines due to inertia. There must be a real force applied over a distance to add energy and inertia does not provide this. Work (and therefore energy) can only be added to a system due to application of a real force.
Since we know that CF is merely a manifestation of inertial resistance to change in direction, it is not a force either, which is exactly why it is defined as fictitious and cannot perform work or add real energy to the system.