A tennis ball moves 24 meters southward, then 16 meters northward, then 18 meters southward, and finally 28 meters
northward.

What belongs in the areas marked x and y? x: the internal energy of a piston system increases as heat is added and rises to a cool area y: as thermal energy is added to a container, some of the energy is lost to the environment x: as thermal energy is added to a container, some of the energy is lost to the environment y: the internal energy of a piston system increases as heat is added and rises to a cool area x: a cold spoon placed in hot liquid gets warmer y: thermal energy is converted to light energy x: thermal energy is converted to light energy y: a cold spoon placed in hot liquid gets warmer