The discussion revolves around the concept of the constant of proportionality in Newton's Second Law of Motion, particularly in the context of linear momentum and force. Participants explore the relationship between force, momentum, and the implications of defining units in physics.
The discussion is active, with various interpretations being explored regarding the definition of units and the nature of proportionality in Newton's laws. Some participants have offered insights into how the unit of force is defined, contributing to the understanding of the constant of proportionality.
There are mentions of assumptions regarding mass constancy and the implications of unit definitions on the proportionality constant. Participants also reflect on the practical implications of these definitions in real-world scenarios.
Dadface said:Expanding on WannabeNewton's post the Newton is defined such that the constant of proportionality is one. Imagine proving by experiment that a is proportional to F/M where the unit of F is yet to be defined. We can write:
a=kF/M
If now we define one Newton as being the resultant force that gives a mass of 1kg an acceleration of 1 metre per second squared then k becomes one.
I could come up with an alternative definition and suggest that the unit of force should be the turnip where one turnip is the resultant force that gives 2.7kg an acceleration 4.6 m/second squared. K would now be an awkward number and I don't think people will use my definition.
Not equal, proportional.Masquerade178 said:Linear momentum is defined as p=mv
Assuming there is no change in mass and differentiating,
you get F=dp/dt