Kai takes a hamburger off of the grill and puts a piece of cheese on it. Explain how and why the cheese melts when Kai puts it on the hamburger.

Answer:

The cheese melts because of conduction, which occurs when two objects of different temperatures are in direct contact. Since the hamburger is warmer than the cheese, thermal energy is transferred from the hamburger to the piece of cheese, causing the temperature of the cheese to rise and eventually melt.