Drew Posted July 9, 2014 Share Posted July 9, 2014 (edited) Hi All: I just broke the tree. Using Drew's previous 200,000 lbs of force required to snap a 24" tree at the location, I've been messing around with some...well..math.... OK. A 700 lb force could outboard on a branch, then run along the branch at 20 mph (an easy feat for a BF, no?). When that force meets the tree and stops, the resultant force is 6,256 lbs. 6,256 lbs at 45 feet creates a 281,520 ft.lb torque at the base of the tree. Boom. Solved. Wag, if yer still out there, you owe me 20 bux. No. You forgot that my experiment involved gravity, which means the weight is accelerating at 9.8m/s^2 You can't just multiply a horizontal force hitting the side of a tree trunk, and multiply it by the height above the base, to get the force at the base of the tree. (I hope my sarcasm meter isn't broken here) Also, my force calculation was how much force would the 700 pound Bigfoot hit the ground at from 45 feet. Here is a little experiment; Imagine a 700 pound beast standing on a 8" diameter limb, 25 feet from the 24" diameter trunk of a 60' tall White Oak tree. Imagine where the weak spots would be, and how many parts of that 8" diameter branch would be weaker than the 24" diameter trunk. Now figure that the rest of that Oak tree would weigh over 10,000 pounds. (This calculation is without leaves or tiny branches) A 24" tree trunk that can handle windgusts blowing against a 10000 pound sail, is not going to be moved by a 700 pound force bouncing on one of it's outer branches. You can play around with the calculations yourself. http://www.woodweb.com/cgi-bin/calculators/calc.pl Edited July 9, 2014 by Drew Link to comment Share on other sites More sharing options...
1980squatch Posted July 9, 2014 Share Posted July 9, 2014 Dude, I know, I was pulling hair out. I should have left em in metric, then converted.... Yeah, you'd have to figger that the deceleration was pretty rapid..... But, I think that it shows it isn't impossible. Hard to believe, absolutely, but not impossible. Yes, you surprised me. I did not think those numbers were going to line up, but they did. You also get the direction of the force applied (right angle to the trunk) to maximize the torque. I'm not saying that is what happened, but if a BF at 20mph somehow managed to slam into a tree truck 45 ft up, the numbers are good. If I was still teaching college physics, this would totally get on my next kinetics/energy exam. SI units though! Link to comment Share on other sites More sharing options...
norseman Posted July 9, 2014 Share Posted July 9, 2014 (edited) Edited July 9, 2014 by See-Te-Cah NC Video embed Link to comment Share on other sites More sharing options...
Drew Posted July 9, 2014 Share Posted July 9, 2014 A physics teacher thinks mass x velocity = Force? No wonder we are in bad shape education wise. Link to comment Share on other sites More sharing options...
Cotter Posted July 9, 2014 Share Posted July 9, 2014 No. You forgot that my experiment involved gravity, which means the weight is accelerating at 9.8m/s^2 In a free fall, in a vacuum, yes, but we're not talking about free falling trees or apes in vacuums. You can't just multiply a horizontal force hitting the side of a tree trunk, and multiply it by the height above the base, to get the force at the base of the tree. Ummmm...yes you can, it's call physics dealing with momentum and moments of inertia. Set up a bending moment diagram (assumed cantilevered at the base) and see what you can come up with. (I hope my sarcasm meter isn't broken here) Also, my force calculation was how much force would the 700 pound Bigfoot hit the ground at from 45 feet. Assuming that the bigfoot and tree are free falling in a vaccuum....??? Here is a little experiment; Imagine a 700 pound beast standing on a 8" diameter limb, 25 feet from the 24" diameter trunk of a 60' tall White Oak tree. Imagine where the weak spots would be, and how many parts of that 8" diameter branch would be weaker than the 24" diameter trunk. Why does the BF have to be standing 25 feet from the base of the tree? Now figure that the rest of that Oak tree would weigh over 10,000 pounds. (This calculation is without leaves or tiny branches) Sure, so that is why the force had to get the tree swaying, to use that 10,000 lbs to its advantage. Another excellent sketch, but not relevant to the discussion on forces at the base of the tree created by a horizontal force at 45 feet. You can play around with the calculations yourself. http://www.woodweb.com/cgi-bin/calculators/calc.pl No thanks, all I need are these 2 equations: F=m*a and M=F*d, That'll get you to the tree breaking solution. Regarding an ape riding the tree to the ground...well, until we can determine the acceleration of the tree toward the ground (sorry bud, it ain't 9.8 m/s^2) we're at a bit of a standstill. Link to comment Share on other sites More sharing options...
norseman Posted July 9, 2014 Share Posted July 9, 2014 http://www.maverickexperiments.com/fma/Force.html Force=Mass x Acceleration I was taught in fluid power that to figure out the force of a cylinder the formula is Pressure x Area of bore = Force. Link to comment Share on other sites More sharing options...
Drew Posted July 9, 2014 Share Posted July 9, 2014 Why would the tree break at the 24" base and not at the point of collision? Where A. The tree would be smaller and less strong and B. Where there wouldn't be 10000 lbs of mass to reduce the vector? Imagine a VW Bug hitting an 8" tree at 30 mph. This would be the result of your Bigfoot running into the side of the tree. Link to comment Share on other sites More sharing options...
Cotter Posted July 9, 2014 Share Posted July 9, 2014 Yes, you surprised me. I did not think those numbers were going to line up, but they did. You also get the direction of the force applied (right angle to the trunk) to maximize the torque. I'm not saying that is what happened, but if a BF at 20mph somehow managed to slam into a tree truck 45 ft up, the numbers are good. If I was still teaching college physics, this would totally get on my next kinetics/energy exam. SI units though! LOL! Yes! Metric rules! I kinda surprised myself, even drew a moment diagram to get me through it. I tell ya, it brought me back to my old college days (degreed Engineer here). Unfortunately in the my 'real world' physics and calculus equations are few and far between. Link to comment Share on other sites More sharing options...
Drew Posted July 9, 2014 Share Posted July 9, 2014 http://www.maverickexperiments.com/fma/Force.html Force=Mass x Acceleration I was taught in fluid power that to figure out the force of a cylinder the formula is Pressure x Area of bore = Force. Yes Norseman, this is why I thought Cotter was pulling my leg. He was using Force x Velocity, which is momentum, not Force. Link to comment Share on other sites More sharing options...
WSA Posted July 9, 2014 Share Posted July 9, 2014 I can't tell a slide rule from a paint stirring stick, but I can affirm with some certainty that a tree going over does not move as a free-falling object would. Slow she goes. Then all at once. That is for a tree felled with a saw. For one experiencing a failure due to wind, it appears to move in slow motion. I saw a 50' VA pine do this once, and it is remarkably gradual. Not saying I would care to ride one of those to the ground, but I could see how it could be a survivable event. Link to comment Share on other sites More sharing options...
norseman Posted July 9, 2014 Share Posted July 9, 2014 Yes Norseman, this is why I thought Cotter was pulling my leg. He was using Force x Velocity, which is momentum, not Force. Big deal? What meaningful difference is there between velocity and acceleration? Got a question for you? What caused all that damage to your smashed car in the photo you posted? The tree? Or the steel cage surrounding it? Link to comment Share on other sites More sharing options...
Drew Posted July 9, 2014 Share Posted July 9, 2014 Are you serious? Have you ever seen a car hit a tree at 30 mph? The tree almost always wins. Link to comment Share on other sites More sharing options...
Cotter Posted July 9, 2014 Share Posted July 9, 2014 (edited) Why would the tree break at the 24" base and not at the point of collision? I already explained that - it's called moment of inertia. Where A. The tree would be smaller and less strong and B. Where there wouldn't be 10000 lbs of mass to reduce the vector? Moment of inertia. Imagine a VW Bug hitting an 8" tree at 30 mph. Moment of Inertia - that same bug hitting it 15 feet off the ground would have a different result. This would be the result of your Bigfoot running into the side of the tree. At the base, assuming the bigfoot was going 30 mph and weighed as much as a VW bug, yes. *image removed* Edited July 9, 2014 by Cotter Link to comment Share on other sites More sharing options...
dmaker Posted July 9, 2014 Share Posted July 9, 2014 Since I'm in a rule making frame of mind, here's another I'd propose, to be posted top/center of the BFF Forum, and I'm only partially joking about it: The preponderance of the evidence at this stage of investigation points to the existence of an unclassified, bipedal animal of unknown nature and origin, and of which we have limited knowledge of morphology, habitat preferences, diet, behavior, mating/reproductive requirements and capacity for communication. All those who are willing to accept this premise and discuss this subject to try and arrive at a greater understanding are welcome. By definition, all those who flatly oppose this premise will have a very limited ability to contribute to the greater understanding of the evidence of this animal. Attempts by those individuals to divert discussion to a debate of this premise will not be tolerated. At what point do you trust yourself and others and make your case? If you are not willing to do this, slap this at the top: (But we don't believe ourselves to the extent where we won't tolerate those who believe we are all crazy or liars). And Cotter, you will never be right to someone who rejects your premise. Ever. (But I'm always impressed by someone who can work numbers like that...) This is the problem. When you present something like that as fact that is not a fact and is only your opinion, then that ignites debate with skeptics. You love to talk about science. A preponderance of anecdotes is a fancy way of saying a pile of unconfirmed stories. Basically you want to re-write the rules of scientific evidence to suit your needs and then enforce them on to the discussion here? Wow. Really, just wow. Link to comment Share on other sites More sharing options...
Cotter Posted July 9, 2014 Share Posted July 9, 2014 A physics teacher thinks mass x velocity = Force? No wonder we are in bad shape education wise. It sure does when the mass is moving at a constant velocity (zero accelleration = no net force), then stops suddenly. The difference between acceleration and deceleration is a minus sign. (That's why 1980 used 1.5 foot stopping distance in his verification). C'mon man! This is basic physics! Link to comment Share on other sites More sharing options...
Recommended Posts