RalphTeichel.
Dear me. Where to begin.
“Gravity is not the only force acting on the ball. If it were, the ball would never leave the jugglers hand.†???
Did you read my posts?
Just to repeat. When the ball is in freefall, between the moment it leaves the hand, and the moment it is caught, the only force acting on the ball is gravity. When it is in the hand TWO forces are acting. Gravity and the push of your hand. The reason the ball does not move when it is in your hand, is because these two forces are equal and act in opposite directions.
“applying energy to the ball sufficient to overcome gravityâ€.
This is the situation when the ball is at rest in the jugglers hand. If he were applying less than ‘sufficient energy to overcome gravity’ the ball would move towards the ground.
“The ball will accelerate away from his handâ€
Only if it has a built in propulsion system.
“The only time when your theory applies is when terminal velocity is reached and the ball is no longer accelerating downwards.â€
No. Terminal velocity is reached when the force of aerodynamic drag is equal and opposite to the force of gravity. In that special case, the accelerometer would read 1G and the ball, although moving would not be accelerating. It would read exactly as if it was in your hand or on the ground. The two forces are equal and opposite so the ball does not accelerate. But the forces are still very real.
“Gravity stays the sameâ€
I already said that several times!
“Do not confuse gravity with acceleration.â€
I’m far from confused my friend. I know they are both exactly the same thing! As I described in a former post, the occupant of a space ship (with no window) accelerating at 1G cannot bring any sense to bear, not use any instrument that can tell him he is not on the surface of earth. He would have to get outside the craft and observe the movements of stellar objects, such as the rapidly receding earth. His frame of reference is self consistent and complete. Only by reference to another frame can he determine if he is moving at all.
“How do you supose aircraft "G" meters work, at all angles and attitudes of an aircraft.â€
Err. Magic? (Sorry, but it is a silly question)
“According to your theory I should never feel a thing when making my aircraft do a loop or pulling out of a dive.â€
Not so. Try reading it again.
“Explain to a combat pilot doing a steep turn, pulling 9 G's with his face almost coming out of his butt,â€
Why would I want to do that?. He probably knows a great deal more about centripetal forces, inertia and gravity than you or I, and will understand easily what my post is attempting to explain.
“Evertime you change direction you are exerting force on an object, even if it is your own body.â€
Like for example the moon? Sometimes it is moving towards the sun, sometimes away from it. Surely it takes a lot of energy to reverse the direction of such a massive object. Where does this energy come from?
Bah!. I give up. It’s getting too hard. I’m having to repeat myself and I feel like I’m wasting my time. Everything you need to know is on the web. Just spend a couple of hours on Wikipedia.
The original question was about using an accelerometer to measure when the ball has reached the apex of it’s flight. The answer is no. The whole time the ball is in flight, an internal accelerometer will read a constant ZERO. If you don’t believe me, try it. An accelerometer CAN however read forces during the catch and throw, and therefore the moment of apex can be estimated with a timer as half the interval between catches. Though, as I have said, I favour the simple mechanical spring impact detector.