Calculate the amount of energy required to vaporize 287 grams of water at its boiling point. Hint: The heat of vaporization for water is 40.68 kJ/mol.

Hot air balloons float in the air because of the difference in density between cold and hot air. in this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. to do this, use the following variables and make these assumptions: the combined weight of the pilot basket together with that of the balloon fabric and other equipment is w. the volume of the hot air inside the balloon when it is inflated is v. the absolute temperature of the hot air at the bottom of the balloon is th (where th> tc). the absolute temperature of the cold air outside the balloon is tc and its density is ďc. the balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. as always, treat air as an ideal gas. use g for the magnitude of the acceleration due to gravity.

Which of these statements explains the difference between nuclear binding energy and the strong nuclear force ?

Arectangle has a diagonal 20 inches long that forms angles of 60 and 30 with the sides. find the perimeter of the rectangle. for geometry