[Jeff]

Bernt - you wrote-: "If the object is already moving in a circle you don't need the B force vector to move it from A to C. You only need a centripetal force from A to Origo to do that. So your diagram need an invard pointing vector to be complete. Origo is the center of the circle, btw."

You don't understand my position. I have simply divided the model into the two forces that are operant when an orbiting object travels in a circular path - a tangential force (operating always in a straight line direction) that supplies energy to allow the oribiting object to travel at a constant speed; and a centripetal force that causes the orbiting object to centripetally accelerate so that it travels along a circular path instead of a straight line path.

In that diagram - the tangential force vector is directed towards B because a tangential force always operates in a straight line direction. The centripetal force (which is directed towards the center of the circle) deflects the orbiting object so that it ends up at point C instead of point B.

You also wrote-: "The centripetal force doesn't do any work in a Newtonian sense. It doesn't increase the speed. It doesn't overcome any resistive loss if any of such is present. It only changes the direction of the mass movement."

I agree that a centripetal force doesn't increase the speed of the orbiting object and that it only changes the direction of the movement of the mass. However, it requires a Newtonian force to change the direction of a moving object, and when that force is operant it is using energy and therefore doing work.

To make it even easier for anyone to falsify my understanding/explanation of "centripetal force action", I am producing this simple example of forces in action.



This diagram represents a birds eye view of person A pushing a lightweight 10'x10'X10' square box across an ice rink. His plan is to push the square box in a straight line direction towards destination D. He works out that it would take him 20 minutes to accomplish that goal - considering the friction drag of the ice against the undersurface of the box. He pushes in a straight line direction towards destination point D. Because of the 10' height of the box he cannot see where he is going, but imagine that person A has an uncanny ability to always apply his constant push force perpendicular to the surface of the box and that he is always pushing in a straight line thrust action.

After 10 minutes, person A stops for a rest and he notes that he has completed 50% of the distance to destination point D (top diagram) - because he is applying a constant straight line push-force against the box.

Now imagine that person A starts pushing again with the same level of straight line push-force. However, he doesn't realise that person B has arrived and person B is also pushing in a straight line thrust against the surface of the box - at a right angle to person A's straight line thrust action. Person B is less strong than person A and applies less push-force than person B.

What happens after 10 minutes? The box ends up at point C rather than destination point D (bottom diagram). The reason is that there is another force present that deflects the moving mass from its straight line path. In other words, that other force changes the direction of the movement of the moving mass, so that it follows a circular path instead of a straight line path. Note that the other force pushes at right angles to the circumference of the circular path - and that it is therefore directing its force towards the center of a hypothetical circle.

It doesn't take much common sense to interpret what I have described.

Person A is supplying a push-force that moves the mass at a constant speed in a straight line direction - and that represents the tangential force.

Person B is also supplying a push-force that is directed at right angles to the tangential force - and that represents the centripetal force.

It should also be apparent that the centripetal force is a Newtonian-type force that is capable of changing the direction of movement of a mass (that is being moved at a constant speed by a constantly present tangential force), and that it is manifesting energy and performing work.

Jeff.