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M1, T3: Phil starts with a Popsicle stick catapult. Then he uses everything he knows about elastic energy to build a full-size catapult that hurls pumpkins! Plus, a maxed out paddle wheel boat and a historical re-enactment (sort of) of how catapults were used in medieval days.
Educational · 14 thg 9, 2015 · 21 phút