Module 4:4 Lesson

Thermal Energy Conductivity

Module 4:4

​Adita ande his friends were learning about insulators and conductors in school. They all agree that the metal, a conductor, will heat up more quickly than ceramic, and insulator. They have different ideas about how the materials will cool. this is what each friend said:

Adita: I think the ceramics will cool quicker than the metal.
Niabi: I think the metal will cool quicker than the ceramic.
Irene: I think they will both cool at the same rate.
Rafi: I think conductors and insulators have nothing to do with how a material cools, just how a material heats up.

Poll

Who do you agree with most?

• Aditia

• Niabi

• Irene

• Rafi

​Kitchenware is made of many different types of materials. Have you ever thought about how those different materials transfer thermal energy? What claim can you make about how kitchenware is made and how these differences affect thermal energy transfer.

How does mass affect the change in temperature of a substance.
Water boils at 100℃, but does the amount of water affect how much thermal energy is needed to start boiling? Examine the figure of the pats to the right. Will the water filling each pot boil at the same time if the energy input is the same for each burner?

In a kitchen you will find all kinds of different materials used for baking, cooking, freezing, and other food related activities. For instance, a pan used to bake bread is made up of metal, but a hot mitt used to remove the bread from the oven if made from cotton or silicone. Does the type of material that something is made out of determine how thermal energy transfers?

How does the type of matter affect the change in Temperature of a substance?

​How does the type of matter affect the change in temperature of a substance

​Specific Heat is the amount of thermal energy required to increase the temperature of 1 kg of material by 1℃. Every material has a specific heat. It does not take much energy to change the temperature of a material with a low specific heat compared to a material with a high specific heat.

Fill in the Blank

Which material has the highest specific heat?

​Conductors and Insulators

Materials are classified into two groups based on their specific heats: Conductors and Insulators. A thermal conductor is a materials through which thermal energy flows easily. The particles in a thermal conductor move easily. So, kinetic energy is transferred easily between particles. Metals are better conductors than non metals. A Thermal insulator is a material through which thermal energy does not flow easily. The particles in a thermal insulator do not move as easily. So, kinetic energy is not transferred easily between particles. 

Fill in the Blank

From the first slide, which material would transfer thermal energy slower?

​The handle of the pan in the figure on the right is made out of wood. Wood is a thermal insulator. The pan is made out of iron-a thermal conductor. Thermal conductors have lower specific heat than thermal insulators. This means it takes less thermal energy to increase the temperature of a thermal conductor that it takes to increase the temperature of thermal insulators of the same mass.

​What other properties affect thermal energy transfer

​Many different properties of a substance can determine how thermal energy will transfer. Some properties include the reflectivity of a substance, the thickness of a substance, and the exposed surface area.

​Reflectivity vs Absorbency
Reflection is when energy carried by a wave bounces of a surface. The opposite of reflection is absorption, or the transfer of energy by a wave to medium through which it travels. The color white reflects all radiated light energy while the color black absorbs all radiated light energy.

​Thickness
The thickness of a substance can determine how thermal energy is transferred. The thicker a substance, the larger the distance the thermal energy has to travel. A larger thickness could increase how long a substance takes to heat up and also delay how long it takes to cool down. Thickness relates to the mass of a substance.

​Surface Area
Surface area is the amount of exposed, outre area of a substance. Increased surface area for a given volume increases the energy transfer between the substance and the surroundings. For example, a shollow bowl has more surface area than a deep bowl. The shallow bowl will transfer more thermal energy to the surroundings.

​As you can see, many factors can affect how thermal energy is transferred between substances. The amount of energy needed to change the temperature of a matter sample by a given amount depends on the sample, and the environment.