Two Plus Two Newer Archives  

Go Back   Two Plus Two Newer Archives > Other Topics > Science, Math, and Philosophy
FAQ Community Calendar Today's Posts Search

 
 
Thread Tools Display Modes
Prev Previous Post   Next Post Next
  #6  
Old 10-23-2007, 07:25 PM
TomCowley TomCowley is offline
Senior Member
 
Join Date: Sep 2004
Posts: 354
Default Re: classical physics - rod anchored to ground, rotational inertia

I'm sure there's an easier way for the first one, but using the initial PE = final KE method, initial PE is 1/2 Mg. Since velocity at the end is proportional to distance from the anchored part of the rod, we can call velocity at distance r kr
Final KE = Int [r on 0,1] 1/2 M (kr)^2 dr = 1/6 M k^2 r^3 evaluated at 1 and 0 = 1/6 M k^2. So 1/6M k^2 = 1/2 M g.

So 1/3 k^2 = g, k=(3g)^0.5, so velocity at the end = k*1 = (3g)^0.5 which is the same answer lifes3ps got.
Reply With Quote
 


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 11:18 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2026, vBulletin Solutions Inc.