Originally Posted by
Marly Lite
Pilotmike, the topple of a childs spinning top is due to gyroscopic precession, not coriolis. Indeed, the properties of gyro instruments are due to both rigidity and precession, and are not related to Coriolis.
You're right about this.
You are right to use the word 'effect' because there is no such thing as coriolis force, it is merely an apparent effect - the path of an object (straight line) relative to a rotating observer. The observer sees the object curving. It is not curving, the observer is! There is no 'Force'.
These effects, or fictitious forces, are not forces at the basic definition that satisfies F=ma, but act like forces to our perception so strongly and consistently, that there's gotta be something to it. We can either yell at people not to call them forces until we're blue in the face, but also we can (as long as we're being careful about it) expand our definition to a higher more general order, that our previous more basic definition becomes a more specific case of. If we're only considering unaccelerated reference frames, then F=ma. However, we act in accelerated reference frames so often, that it's really more convenient to go ahead and use those frames, and account for them in the definition. So, the "a" of the frame, ends up being a fictitious/apparent "F" within the frame. And we end up with our familiar (and often wrangled over) centrifugal force. If I'm pulling 10 G's in an aerobatic plane (let's disregard Earth's gravity for simplicity), there's sure as hell a force that I can both feel in my body and measure with a force meter. What's happening?
Unaccelerated reference frame (aka inertial reference frame, aka outside observer, aka absolute reality, as much as there can be one):
The airplane is accelerating around the curve toward the center (centripetal acceleration), and applying a force equal to that times my body's mass, to my body.
Accelerated reference frame (observer inside the plane):
I am feeling a force away from the center of the curve (centrifugal force), toward the floor of the airplane. If I drop an object, it will accelerate at an acceleration equal to the weight of that object divided by its mass.
In both cases, F=ma. But in the first case the a is the motion of the body within the frame, while in the second case it is the motion of the frame itself. Like many problems, it's really an issue of definitions and accounting. It's gerrymandering the border around what you consider to be a part of the system, vs. outside of it.