Hot water is poured into one glass, and cold water of the same mass is poured into the other.

Hot water is poured into one glass, and cold water of the same mass is poured into the other. In which glass does the water have more internal energy?

Despite the fact that both glasses contain the same substance, hot water has more internal energy. Because in hot water the speed of movement of molecules is greater, which means that the kinetic energy of the substance is greater. And since the internal energy of a substance is made up of its potential and kinetic energy, therefore, the internal energy of hot water will also be greater.