A student in a middle school classroom is throwing sharpened pencils into the ceiling while the sub is not looking. The pencil has a mass of 0.006 kg and is being thrown at a ceiling tile (mass of 0.5kg) with velocity of 40.0 m/s. In a closed system what would be the velocity of the ceiling tile and pencil after this inelastic collision. Set your coordinate system as positive in the direction that the pencil is thrown.

Total solidification times of three casting geometries are to be compared: a sphere, a cylinder, in which the length-to-diameter ration - 1.0, and a cube. volume = 1000 cm^3 for all three shhapes, and the same casting alloy is used. a) determine the solidification times of each geometry b) based on the results of part (a), which geometric element would make the best riser? c) if the mold constant = 3.5 min/cm^2 in chvorinov's rule, compute the total solidification time for each casting.