What is a "real force"? Has anybody come across the term "real force" before? My textbook defines it as follows:

"A real force is a force which acts on an object due to another object. An isolated object(far from all objects doesn't experience any real force."

What must I make of this absurd definition?  
 A: A real force is a force with reaction force, which satisfies Newton's third law. Fictitious forces have no reactions.
A: See the comment... what you should understand though in that respect is that forces always have their agents. 
Dynamic force - physical bodies, ropes, bullets, whatever you encounter in your early undergraduate physics life
Dissipative (friction, tension...) - complicated... can be phonons, plasmons, molecular vibrations etc.
Electromagnetic - photons
and so on...
You can classify them in any way you want... But what the textbook calls real is rather dynamic. I have never heard of "real" forces, lol... real forces, real dudes=)))
A: You are right: that proposition is a mess but we can try to to shape it up to make some sense.
I suppose you know the difference between a real force and an unreal or fictitious force. In case you do not know, the latter is one of the many artifices of ancient physicists who tried to deal with phenomena they did not fully understand. A fictitious force is what a naive observer would suppose to explain a motion which is not real, but which depends on the frame of observation. If it is not clear and you never heard, for example, of Coriolis force, think of planets that appear to move in a backward direction, or the moon itself or the Sun that seems to move around the earth.
A real force is a source of energy, and more precisely of kinetic energy. That can be a charge attracting or repelling other bodies, or the muscle of you body expanding and setting a ball in motion.
That was the cryptic meaning ot your book:


*

*the abstract 'real force' 

*in a real object (your muscle) acts 

*on another object (the ball) 

*due to the other object (your physical muscle)

A: A good example of a non real force is the well known centrifugal force. It is only an apparent force that acts on a mass in a circular rotation movement (for example). Using this apparent force allows to process simple mechanics operation relative to moving mass as if it did not move.
