Drexel dragonThe Math ForumDonate to the Math Forum

Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.

Math Forum » Discussions » Education » math-teach

Topic: Physics problem --ball rolling down an inclined plane
Replies: 8   Last Post: Dec 26, 2012 10:25 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Peter Duveen

Posts: 163
From: New York
Registered: 4/11/12
Re: Physics problem --ball rolling down an inclined plane
Posted: Dec 26, 2012 10:25 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Well, Kirby, nice to know people are paying attention to the issue. Regarding the first link,

"If you "race" these objects down the incline, they would definitely not tie! This is because Newton's Second Law for Rotation says that the rotational acceleration of an object equals the net torque on the object divided by its rotational inertia. (Net torque replaces net force, and rotational inertia replaces mass in "regular" Newton's Second Law.)"

My sense in reading Newton's Principia is that he wanted to steer clear of rotational problems. "Newton's Second Law for Rotation" I dare say did not exist. This is one problem with a very common approach to the teaching of mechanics. It is first promised that Newton's laws will explain everything, and then there is a switch and bait, an introduction of new principles, such as torque, etc. that are really not derivable from the first three laws, or at least no derivation is given, if one is indeed possible. In fact, the principle of conservation of energy is also an extraneous principle not included in Newton's tool kit. You don't think this is confusing to students? It certainly got me confused back then.

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© The Math Forum 1994-2015. All Rights Reserved.