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?
Answer
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)
No comments:
Post a Comment