Day 98 – Breaking Bridges

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Engineering Physics – Today we broke the bridges that students made. The previous attempt to break them was messy: I was hanging a bucket from the bridge where the bucket contained sand and hanging masses.  The buckets weren’t heavy enough so we then started stacking textbooks on top of the brides.  Once we got to 40 kg I called it off, as I didn’t want spilt sand and textbooks all over the place.

I built this bridge press in about 30 minutes, plus another hour for going out and buying the threaded rod.  The nuts gradually press the top beam down on the bridge and we monitor the bathroom scale for how much force is applied. Students used their phones to video record the scale because once the bridge breaks, the reading drops instantly.

There weren’t many broken popsicle sticks, almost all of the failures were with the glue. We used Staples washable white glue because it was cheap, but I wonder if the “washable” part makes the glue a lot weaker.

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