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Bricks are 20cm long and 10cm high. How high could an arch be built without mortar on a flat horizontal surface, to overhang by 1 metre? How big an overhang is it possible to make like this?
How high can a high jumper jump? How can a high jumper jump higher without jumping higher? Read on...
A cone is glued to a hemisphere. When you place it on a table in what position does it come to rest?