To: Lu,
I can scarcely believe that you think all physicists have got it wrong, but you said it! Are you sure? Perhaps this is another example of the fact that some instructional books simplify discussions so that intellectual “weenies” can understand enough to do their jobs without having to get deeper (aka gyroscopic precession). Perhaps a formal qualification course may have cleared this up for you. Although perhaps Nick is wrong – you are no crackpot, the world’s scientists however, must be!
Lets look at your factual story of David and Goliath:
You said (and we will use numbering for specifics here):
1. Lu said: >>Centripetal force is not a force at all. It would not exist if there were no centrifugal force.<<
My response: I love a good double negative as a proof. You are saying that if there was no centrifugal force there would be no centripetal force. Yet you are arguing that there is a centrifugal force. Therefore, using YOUR OWN logic, there must be a centripetal force. Accordingly you do not agree with your own opening sentence that centripetal is not a force! Wonderful stuff.
2. Lu said: >> His slingshot was rotated in a circle and his hand restrained any outward movement of the rock in the slingshot<<
My Response: No Lu, his hand created the torque to propel the rock. As an acceleration has a direction, there must be a force constantly changing the direction of the rock (because it is going around an arc). You have correctly identified that there is such a force, but it is the sling restraining the rock from flying out. Scientists (though they may all be crackpots) term the force exhibited by the sling as centripetal force, in other words: a force acting toward the center to that continues to change the direction of the rock.
3. Lu said: >> when the slingshot was let go the rock went out in a straight line and not at a tangent<<
My Response: A straight line from a circle IS a tangent. But if you mean it flew at off at right angles to the circle, you need to do a vector analysis. In order for it to fly off at right angles, you must have instantly stopped all momentum about the circle at the precise moment of release, leaving only the force exhibited by the sling which now removed allows the ball to fly outwards. I can hear you nodding Lu. Here is the clincher though: the outward momentum as you call it, is entirely generated by the directional change of the rock about the circle, therefore, the instant you stop the momentum around the circle at release point, you would also stop any momentum outwards, and the rock would not fly off at right angles, or any other direction. I cannot wait for you vector analysis here.
4. Lu said: >>Once again I must caution that anybody that resorts to college texts to prove a point will have a hard time in any industry <<
My Response: Perhaps then, it would be better if we all stopped going to college and began reading simplified texts. Perhaps we should have stayed believing in the fact that the earth was flat because it was simpler, and allowed us to do our job. Or maybe they should never college qualify engineers because they will have a hard time in industry. I am sure we would still have all the incredible surgical machinery, all the amazing laboratories that allow the manufacture of life saving drugs, etc, if we had not sent any of them to college. What amazing thing have you brought to the helicopter world thus far Lu?
5. Lu said: >>When you get into an engineering slot you will use that companies design handbook as your bible and you can throw your textbooks away<<
My response: To me, this is the crux of the problem. Company design books are designed such that they are the most easily understood text for all levels of qualified and non qualified personnel to follow so that there is NO room for misinterpreting procedures which may cause accidents, etc. They are not college text books aimed at helping design of the aircraft, or systems. Get it?
Same point being made over and over and over and over………
Dont mean to be so harsh Lu, but calling all scientists "weenies" is very offensive.