Ok, I guess those are the only replies I will get. No big deal. Both answers are correct, the second one more correct. I can make either string break by pulling on the lower string either fast or slow. The whole point of this is that it illustrates WHAT PART of the tree may suffer damage when it is hit by an object slowly or quickly. While it's not likely any cars will be hitting trees in the upper half, suppose one did. Think of the root system as the upper string, the lower half of the tree could be considered the weight, and the upper half of the tree could be considered the lower string. From experience I can tell you that it IS possible to pull certain types of pine trees out by the roots, but I don't know about various others. Of course it also depends on the type of soil. Now that I think about it, suppose you have a tree with a somewhat flexible topsection and hit the top of the tree quickly. The inertia in the bottom of the tree would keep the shock out of the root system and the top of the tree would just bend over and let the car sail by. But suppose you hit it at a slower speed. Would the inertia in the main trunk be overcome and rip the roots out? Maybe such trees don't occur in nature, but I'll bet a structure could be designed to behave this way. Any thoughts?
