In the history of astronomy, which of the following is true? . a] tycho brahe built one of the first observatories. b] ptolemy was criticized for his work on the heliocentric model. c] nicolaus copernicus argued that the sun was the center of the universe. d] johannes kepler argued that earth was the center of the universe. .

Which two objects have the greatest gravitational force acting between them

Iron reacts with sulfur to form iron sulfide. if 60 grams of iron reacts with sulfur to produce 90 grams of iron sulfide, how much sulfur has been used in the chemical reaction?

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.