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the physics breaking up an old table

Ben Shelton


when you put a shovel on an old picnic table in your backyard and a leg of the table snaps, it's time for a new table. Problem is, the table can't be thrown away or used for firewood (some parts are just too rotted for anything put the garbage) as it is. It had to be taken apart. The first thing I did was pry off the crossbeams on the table's underside. The crowbar had to be placed at a 90 degree angle and then hammered underneath the crossbeam and pulled. The trick was to make sure the sideways pressure on the crowbar was transferred into the right place. Without something holding the main beams in place, the crossbeams would just pull up the main beams, because energy is always transferred and an object in motion (the main beams nailed to the cross beams) will remain in motion unless acted on by an outside force (my foot). With nowhere else to go, the nails where forced to separate from the board. Next I had to brake up all the beams with an ax. the acceleration of my ax would transfer onto the board, driving the head into the board. The motion I made with each swing was a half circle. sometimes the force would be so great and the wood so rotten, the energy would be transferred too fast for the board and it would break on the first try! These demonstrate two basic laws of physics: an object in motion will stay in motion unless acted on by an outside force; and energy will never be destroyed or created, only transferred. That table sure was destroyed though!


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