Change Forum... Civil Aviation Travel, Polls & Prefs Tech/Ops Aviation Hobby Aviation Photography Photography Feedback Trip Reports Military Av & Space Non-Aviation Site Related LIVE Chat My Starred Topics | Profile | New Topic | Forum Index | Help | Search
 Need Help: Physics!
 FlyVirgin744 From United States of America, joined Jul 1999, 1313 posts, RR: 1Posted Thu Mar 6 2003 19:22:10 UTC (13 years 2 months 3 weeks 2 days 17 hours ago) and read 2523 times:

 Hey guys, I've been stuck on this problem for awhile. Maybe someone can help me. Figure 11-43 shows two blocks, each of mass m = 3.2 kg, suspended from the ends of a rigid massless rod of length L1 + L2, with L1 = 0.20 m and L2 = 1.8 m. The rod is held horizontally on the fulcrum and then released. What are the magnitudes of the initial accelerations of (a) the block closer to the fulcrum and (b) the other block? Now the answer to this situation is 0.956 m/s^2 and 8.60 m/s^2. But next time I do it I will get new numbers. Can anyone help?
 Sometimes I go about in pity for myself and all the while a great wind carries me across the sky.
 Airways1 From United Kingdom, joined Jul 1999, 563 posts, RR: 0 Reply 1, posted Thu Mar 6 2003 20:13:07 UTC (13 years 2 months 3 weeks 2 days 16 hours ago) and read 2504 times:

 I've just done a quick calculation, and I think the answers are (a) 0.16 m/s^2 (b) 1.44 m/s^2 I will post again if I come up with a different answer. airways1
 JetService From United States of America, joined Feb 2000, 4798 posts, RR: 10 Reply 2, posted Thu Mar 6 2003 20:15:46 UTC (13 years 2 months 3 weeks 2 days 16 hours ago) and read 2499 times:

 Ask David B. He's an expert on massless rods.
 Staffan From , joined Dec 1969, posts, RR: Reply 3, posted Thu Mar 6 2003 20:19:48 UTC (13 years 2 months 3 weeks 2 days 16 hours ago) and read 2496 times:

 Hi, First calculate the torque around the fulcrum. T=L2*F2-L1*F1 Then use Newton's second law for rotation T=I*a/r (r=L in this case) where I=I1+I2 and I1 and I2 are the moment of inertia for each of the two blocks added together (I=mr^2) This gives a1=(T*L1)/I and a2=(T*L2)/I I got the answers you posted above doing it this way. Hope it helps! Staffan
 Airways1 From United Kingdom, joined Jul 1999, 563 posts, RR: 0 Reply 4, posted Thu Mar 6 2003 20:25:00 UTC (13 years 2 months 3 weeks 2 days 16 hours ago) and read 2493 times:

 I seem to have the same problem as you - I get a different answer each time. Now I have (taking g=10N/kg) (a) 0.99 m/s^2 (b) 8.89 m/s^2 I thought my previous answer seemed a bit low... airways1
 FlyVirgin744 From United States of America, joined Jul 1999, 1313 posts, RR: 1 Reply 5, posted Thu Mar 6 2003 20:57:44 UTC (13 years 2 months 3 weeks 2 days 15 hours ago) and read 2482 times:

 That was it Staffan, thanks a lot
 Sometimes I go about in pity for myself and all the while a great wind carries me across the sky.
 Toner From United States of America, joined Feb 2003, 268 posts, RR: 0 Reply 6, posted Thu Mar 6 2003 21:00:54 UTC (13 years 2 months 3 weeks 2 days 15 hours ago) and read 2482 times:

 http://panda.unm.edu/courses/finley/P160/HW/HW31Sol.html
 Flight152 From United States of America, joined Nov 2000, 3508 posts, RR: 6 Reply 7, posted Thu Mar 6 2003 21:17:15 UTC (13 years 2 months 3 weeks 2 days 15 hours ago) and read 2476 times:

 JetService..your a math expert. Can you ramble off some of your bullshit errr.. math knowledge?
 JetService From United States of America, joined Feb 2000, 4798 posts, RR: 10 Reply 8, posted Thu Mar 6 2003 21:37:07 UTC (13 years 2 months 3 weeks 2 days 14 hours ago) and read 2467 times:

 Flight152, I was going to see if someone else could help first. I hate to be a know-it-all, but after seeing the responses, I guess I have to. FlyVirgin's first problem is his polyfractals are all askew. He doesn't realize (as most of the population, except me) that whenever you have two opposing unilinial lengths on a reflective plane, it immediately puts the fulcrum in an opposing mass state. This basically inverts your polyfractals incrementally, thus skewing them. To compensate when calculating the overall static basis, all you have to do is place your variables (L) in the same matrix as the subvortex. Otherwise you end up with a coefficient leak. And everyone know that a coefficient leak, while durinominal, is only a raw element in a saturated array. Hope that helps.
 Tbar220 From United States of America, joined Feb 2000, 7013 posts, RR: 23 Reply 9, posted Fri Mar 7 2003 01:13:28 UTC (13 years 2 months 3 weeks 2 days 11 hours ago) and read 2449 times:

 ROFL JetService!!
 NO URLS in signature
 Top Of Page Change Forum... Civil Aviation Travel, Polls & Prefs Tech/Ops Aviation Hobby Aviation Photography Photography Feedback Trip Reports Military Av & Space Non-Aviation Site Related LIVE Chat Forum Index

This topic is archived and can not be replied to any more.

Printer friendly format

 Similar topics: More similar topics...
Volunteering At A Hospital; Need Help And Advice posted Sat Aug 22 2009 16:24:33 by MCOflyer
Need Help Getting To Sleep posted Thu Jul 16 2009 00:47:34 by Af773atmsp
I Need Help With A Gay Guy... posted Tue Jul 14 2009 17:56:45 by 7324ever
I Need Help Traveling The Mbta Sbway Possible? posted Wed Jun 10 2009 12:31:20 by StarAlliance38
Need Help With Dialing A Number posted Fri May 29 2009 11:14:46 by Wardialer
Need Help With German Language posted Sun Mar 8 2009 16:09:37 by B727
BMW 3 Series Owners, Need Help Re:run Flat Tires posted Wed Feb 18 2009 23:24:38 by FLY2HMO
Need Help In Choosing A Boston Hotel posted Mon Oct 6 2008 15:46:01 by ScarletHarlot
Need Help With A British Saying posted Fri Sep 12 2008 07:34:36 by Don81603
Need Help: Info About ICN posted Fri Aug 22 2008 16:48:08 by Transpac787