Talk:Newton's laws of motion

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I HAVE A question that if a person in a spherical ball pushes at one side it moves but internal forces must be canceled by newtons 3rd law. How this happens? if you get answer please post it to <email redacted>.

Hello, we do not answer questions via email. As such, I have removed your email address from this page. This page is also for talking about the article itself, not the subject in general- you can do that at the Reference Desk on the English Wikipedia. Cheers, sonia 07:35, 11 September 2010 (UTC)

Newton's Second Law[change source]

Newton's second law concerns rate of change of momentum; not 'mass * acceleration', which is a consequence of rate of change of momentum with constant mass. I know this is a little hard to put into simple terms but the alternative F=ma is not actually NII. Veltas (talk) 15:18, 22 November 2011 (UTC)

"Backwards" spinning wheel?[change source]

The example of the 3rd law using the car is a little unclear: "A car has wheels which spin backwards." My concept of backwards spinning wheels says that the car would move backwards, but that's not what is being illustrated here. What is the definition of "backward" motion of a rotating circle? Could this be made clearer by removing spin direction and focusing on car direction somehow? That whole example leaves me less sure how to teach this material than when I started.

Overkill in the first law?[change source]

Wherever I see the First Law written out, it always says "at rest or moving at a constant velocity". Given that "at rest" is at a constant velocity (i.e. 0), why isn't this shortened to simply "a object at a constant velocity"? Is there a reason for specifically stating 0 ms^-2 separately, or is it simply another conventional current-style thing, where an irrational idea persists simply because people are too lazy to change it? (talk) 15:06, 4 June 2012 (UTC)