A-aron Posted September 19, 2014 Report Share Posted September 19, 2014 So I've forgotten how to do the balancing of weight on a fulcrum etc. I believe I have the correct formulas but am a little lost on what to do. These are from a study guide I am working on, but I do not think I will be able to meet with the instructor prior to the test so I figured I would come here and try and get some help. If anyone is willing to help, the work you did would be appreciated so I can try and figure it out on my own. Question 1How should the 250lb weight be shifted to balance the plank on the fulcrumOne thing that is throwing me off and is making me unsure is that the plank has a weight of 200lbs and is offset of the fulcrum by 15 inches. So do I take into account the weight of the plank? do I use the 15" to find the moment or do I use 45" I believe the formulas areDistance= Total Weight x CG/ Weight Shifted and CG= Total of Moments/Weight Question 1 has answers of1 inch left1 inch right2 inches left2 inches right Question 2If 300 lbs of weight is located at point X and 150 lbs at point Z, how much weight must be located at point Y to balance the plank. I believe I have this one figured out correctly but figured I would put it here to just verify. I did50(300)+(25)Y=(100)15015000+(25)Y=15000 15000+(25)Y=15000-15000 -15000(25)Y=0 Answers of1000lbs100lbs10lbs0lbs Quote Link to comment Share on other sites More sharing options...
eagle5 Posted September 19, 2014 Report Share Posted September 19, 2014 Damn! The only formulas I really know about w & b are weight × arm = moment, then divide total moment by total weight. Glad no one asked me your question! Quote Link to comment Share on other sites More sharing options...
Pohi Posted September 19, 2014 Report Share Posted September 19, 2014 (edited) Faa-h-8083-1a page 21 is what you are looking for. Google faa aircraft weight and balance handbook Edited September 19, 2014 by Pohi Quote Link to comment Share on other sites More sharing options...
Tom22 Posted September 19, 2014 Report Share Posted September 19, 2014 Set the first problem up as you did the second – 2” left. Quote Link to comment Share on other sites More sharing options...
A-aron Posted September 19, 2014 Author Report Share Posted September 19, 2014 Set the first problem up as you did the second – 2” left. Yeah I ended up figuring it out. Thanks for the help anyways guys. I was using the FAA weight and balance handbook but I was kinda confused on how the plank weight came into play. I found out just doing simple algebra was easier than trying to work out of the weight handbook. 1 Quote Link to comment Share on other sites More sharing options...
WolftalonID Posted September 20, 2014 Report Share Posted September 20, 2014 Thats exactly it, you nailed it on the head. It falls back the the old K.I.S.S. Formulas of math!! Quote Link to comment Share on other sites More sharing options...
rotornut67 Posted September 20, 2014 Report Share Posted September 20, 2014 Buy the ibal app for your iphone or ipad...I love it. You can email it to yourself and keep the data for your records if you want. I've checked it on a few occasions by computing it manually. It has always been spot on. Quote Link to comment Share on other sites More sharing options...
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