Why Do Different Materials Affect Temperature Change in Containers?

[sasuke07]

Homework Statement

Hi so i have a few questions on thermal properties, the questions are supposed to be conceptual with no calculations.
1. There are 3 containers. They are made of plastic, glass and alluminum. If you put hot water into the 3 containers, why is there is small difference in temp. change between the 3 containers and large difference in their thermal conductivity.
2. The outside of a refrigerator is made of metal, plastic and insulation. We were supposed to pick one of the 3 materials and why its drastically important than the other two. I picked insulation and basically said that its more important for the function of the fridge because it reduces heat flow. But i got it wrong. Could someone help me on these 2 questions.

Homework Equations

No equations necessary.

The Attempt at a Solution

 

[jbsteele]

For the first question, the difference in temperature change between the three containers is due to the different thermal conductivities of the materials. Glass and plastic have much lower thermal conductivities than aluminum, which means that they are not as good at transferring heat energy. This means that the water in glass and plastic containers will take longer to heat up and cool down than the water in the aluminum container. For the second question, the insulation material is the most important for the function of the refrigerator because it helps to reduce the amount of heat transferred from the outside to the inside of the fridge. Insulation reduces the amount of heat flow by providing a barrier that traps air and slows down the transfer of heat energy. The metal and plastic materials help to create a strong and durable exterior for the fridge, but it is the insulation that helps to keep the cold air inside and the hot air outside.