Item NG089003: The total amount of energy in a lunch box containing only an ice pack and the air around it remains the same even after the ice pack gets warmer and the air gets colder. (This item uses bar graphs to depict the amounts of each form of energy.)

A person takes an ice pack out of the freezer and places it in a small empty lunch box.  The person closes the lunch box.  Assume that no energy is transferred into or out of the lunch box when it is closed.  The following graph shows the thermal energy of the ice pack and the thermal energy of the air in the lunch box right after the person closes the box.  The graph also shows the total amount of thermal energy (the sum of the amounts of thermal energy of the ice pack and the air in the lunch box).

         

After a while, the ice pack will be warmer than it was at the beginning, and the air in the lunch box will be cooler than it was at the beginning.  Which of the following graphs represents the thermal energy of the ice pack, the thermal energy of the air, and the total amount of energy when the ice pack is warmer and the air is cooler?  (Remember that no energy is transferred into or out of the lunch box when it is closed.)

 


Statistics for this item are available in the Original Project.