I have read this forums discussion about inertia these past weeks with increasing amusement. It is truly incredible what conclusions physics students of clearly undergraduate calibre are capable of. I sometimes marvel at the fact that this country is able to produce any physicists with half a brain at all. To the point however. There have been many comments and claims pertaining to the definition of inertia that attempt to deny any association with velocity, acceleration, and in one instance even mass. One individual declaring himself an authority even goes so far as to declare that inertia is not quantifiable. What utter nonsense. May I remind you all that Newtons first law is clearly and precisely described and quantified by Newtons second law. Yes yes, it is true we do not have a ?unit of inertia? per se. That being said, it is absurd to think of inertia as unquantifiable, unvarying, or unassociated with mass and acceleration. Any object has a quantifiable resistance, impedance if you prefer, to a change in its velocity to any other given velocity, and that resistance is reflected clearly and precisely in the amount of force required to achieve that acceleration. It will take twice as much force to accelerate a 10 kilo object from a one velocity to another as it will take for a 5 kilo object. Why ??.. the blatantly obvious reason is because the 10 kilo object has twice as much inertia. Likewise, if you have two equal masses and wish to accelerate one twice as much as the other, it will require twice as much force to do so. Again because the inertia of one is twice that of another. You may think of inertia is a mirror image of force. That Newtons second law chooses to express this relationship in terms of force rather then resistance is superfluous to the understanding of the nature of inertia. Force is simply flipside of inertia and likewise. That students are not taught to think in these terms has a reasonable enough explanation, it is for most purposes better to use other physics tools and constructs to describe the various systems we wish too describe. That said, any student of physics should be able to put 2 and 2 together and see the sense in any perspective, especially one so simple, regardless of whether it is usual or not. I should perhaps mention that I am a PhD, and teach graduate level applied physics / acoustics and have done so these past 35 years. I would suggest that at least three of the participants who portend a level of authority consider going back for a serious brush up. I do not intend to get involved in any discussion here, and have no intention of fielding any flurry of protests and questions. Dig back into your college texts and think about what you read there. Seasons Greetings Calin Thomason. -- ___________________________________________________ Check out the latest SMS services @ http://www.operamail.com, which allows you to send SMS through your mailbox. Powered by Outblaze
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