Timeline for Is Newton's second law tautologous? [duplicate]
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| Nov 19, 2015 at 20:18 | history | closed |
user10851 CommunityBot |
Duplicate of Are Newton's "laws" of motion laws or definitions of force and mass? | |
| Nov 19, 2015 at 19:14 | comment | added | commando | Regarding the title question, at least: I am reminded of Wittgenstein's observation that all propositions are tautologies. Newton's Laws are declarations of equality. They are saying, "this is true, always". They are defining tautologies, by saying, "look at this thing on the left side. If you write it a little differently it's the thing on the right". | |
| Nov 19, 2015 at 18:37 | review | Close votes | |||
| Nov 19, 2015 at 20:25 | |||||
| Nov 19, 2015 at 18:35 | comment | added | gatsu | As you may have heard from general relativity, the "force of gravity" is not really a force in the conventional sense; in fact it is again chosen so as to fit with the dynamical observations, Kepler's laws in particular. One may postulate a reference force formula like the weight of an object or Hooke's law for instance, but then the meaning of the second law becomes dependent on this postulate and its violation could mean either that the second law is wrong or that the constitutive law is wrong: how do you choose which is the case? | |
| Nov 19, 2015 at 18:22 | answer | added | gatsu | timeline score: 2 | |
| Nov 19, 2015 at 17:55 | comment | added | AlQuemist | This question is actually about the meaning of “force” in Newton’s laws. In practice, one finds the form of the force in the second law by observing the motion of bodies under such a force (i.e., the change in their momentum); e.g., looking at the orbits of heavenly bodies, and deducing the $\frac{1}{r^2}$-dependence of the gravitational force. | |
| Nov 19, 2015 at 17:30 | history | protected | Qmechanic♦ | ||
| Nov 19, 2015 at 17:26 | answer | added | user99035 | timeline score: 0 | |
| Nov 19, 2015 at 17:14 | comment | added | Qmechanic♦ | Possible duplicates: physics.stackexchange.com/q/70186/2451 and links therein. | |
| Nov 19, 2015 at 17:11 | vote | accept | AGML | ||
| Nov 19, 2015 at 17:27 | |||||
| Nov 19, 2015 at 17:10 | answer | added | gented | timeline score: 6 | |
| Nov 19, 2015 at 17:09 | answer | added | WillO | timeline score: 2 | |
| Nov 19, 2015 at 17:00 | comment | added | user83548 | @Vishwaas that is a common misconception, the equation only works if you assume constant mass | |
| Nov 19, 2015 at 16:56 | history | edited | Qmechanic♦ |
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| Nov 19, 2015 at 16:41 | history | asked | AGML | CC BY-SA 3.0 |