This discussion centers on the interpretation of Newton's laws of motion, particularly the first two laws. Participants argue that Newton's first law, which states that an object in an inertial reference frame will maintain its velocity unless acted upon by a force, is definitional rather than a law. They assert that the second law, expressed as F=ma, is a mathematical definition of force rather than a fundamental principle. The conversation highlights the ambiguity in defining 'force' and 'inertial frames' and emphasizes that Newton's laws gain significance when contextualized with the laws of forces, such as gravity.
PREREQUISITESStudents of physics, educators explaining classical mechanics, and anyone interested in the foundational concepts of motion and force in the context of Newtonian physics.
Jano L. said:When you put many heavy books on a plastic table, you will see that the table deforms. There is force between the table and the books, but no acceleration.
Delta² said:yes but the deformation happened because some of the points of the plastic table (the points under the books where the deformation happened) were accelerated abit and then they stop abit lower.
stevendaryl said:In the case of balancing forces, the TOTAL force is zero. But gravity still exerts a downward force, and the desk still exerts an upward force.
stevendaryl said:So force is not defined in terms of accelerations.
DrStupid said:According to the second law there are corresponding changes of momentum that are balanced too.