The second law is essentially a definition of force. Mass could be defined informally as a property of matter that resists acceleration.Which part of Newton's second law is definition and which part is law content?It seem that there is a violation in logic, because we define the notion of force through the notion of mass, then we define the notion of mass through the notion of force when we consider the second law.
I'm sorry to say I cannot make any sense of what you've written.Is it because the force is a reality,it exist before there is a definition of it,so we do not need a logic argue here(we need not avoid a circularity here)?
Because it's an empirical science. It's not a branch of logic.I do not understand why a science subject not follow a principle of logic?
Yes, the true test is that it matches experiment.So we define notions referencing to each other,then we prove experimentally the definition is not self contradict in all cases, then it is OK?
Gravity would do as a standard force, for example. You can balance two masses on a set of scales. That takes you into the practical world of weights, measures and equipment calibration.If we define force as product of mass and acceleration,then when we compare the test mass with standard mass(1kg) we must use the same force and measure accelerations.But how do we define the same force acting on standard and testing masses?
PS One point to note is that this works. We're able to build aircraft or whatever based on classical physics and a practical approach to measurement.Gravity would do as a standard force, for example. You can balance two masses on a set of scales. That takes you into the practical world of weights, measures and equipment calibration.
Yes. We postulate several quantities and the relationships between them. If it matches observation we use it.So we define notions referencing to each other,then we prove experimentally the definition is not self contradict in all cases, then it is OK?
Newton's second law is law content only. All related terms are defined seperately:Which part of Newton's second law is definition and which part is law content?
No, there is no violation of logic. Definitions don't need to be explicit - not even in mathematics (see Hilbert's axioms).It seem that there is a violation in logic, because we define the notion of force through the notion of mass, then we define the notion of mass through the notion of force when we consider the second law.
It is possible to take mass as a fundamental entity and use Law II as a definition of force. It is also possible to take force as a fundamental and use Law II to define mass. Different textbooks have tried the different approaches, with those textbook authors and others arguing in the literature as to which is better. I would say that the former approach has tended to win the day. Especially since the SI defines the unit of mass as fundamental and the unit of force as derived.Which part of Newton's second law is definition and which part is law content?It seem that there is a violation in logic, because we define the notion of force through the notion of mass, then we define the notion of mass through the notion of force when we consider the second law.
Except I see no reason to refer to one or the other as either theoretical or experimental.So are there (possibly) two types of definition: theoretical definition(e.g definition force as through acceleration and mass) and experiment definition(E.g definition of force as through the deflection of spring using in experiments)?(But we consider them equivalent)