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Which of the following best explains why the end of a spoon sticking out of a cup of hot water also gets hot? question 7 options: the heat from the hot water is conducted through the spoon handle the hot water heats the air surrounding the upper part of the spoon. the hot water causes a physical change in the spoon handle. the hot water causes a chemical reaction to take place in the spoon.

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.

Imagine that you push on a large rock. at what point does your effort change the rock’s mechanical energy?