How Thermal Energy Spreads SPI’S: Chapter 9 Lesson 2 How Thermal Energy Spreads SPI’S:

How many of you used a toaster this morning. How about a hairdryer How many of you used a toaster this morning? How about a hairdryer? A refrigerator? These are all examples of devices that control the transfer of thermal energy ;

The main idea of this lesson is to understand: How thermal energy spreads.

Take out your science journals… VOCABULARY: Take out your science journals…

VOCABULARY: Conduction – the direct transfer of thermal energy between touching objects

VOCABULARY: Conductor – a material that easily transfers thermal energy or electricity.

VOCABULARY: Convection – the transfer of thermal energy by the flow of liquids or gases.

VOCABULARY: Heat – the transfer of thermal energy from warmer areas to cooler areas.

VOCABULARY: Insulator – a material that does not easily transfer thermal energy or electricity.

VOCABULARY: Radiation – the transfer of thermal energy through electromagnetic waves.

VOCABULARY: Temperature – the measure of the average kinetic energy of the particles that make up a substance.

VOCABULARY: Thermal energy – the kinetic energy of the particles that make up a material.

Let’s read about Temperature and Thermal Energy on PP. 336 and 337 Be sure to listen for the vocabulary words “Thermal Energy” and “Temperature”

Quick… What’s the main idea of this lesson? I know you know this…

How thermal energy spreads! I knew you’d get it…

Take a look at the photo on P. 337 If the temperature of the liquid in the urn is the same as the temperature of the liquid in the cup, what is the difference in the amount of thermal energy?

Take a look at the photo on P. 337 The liquid in the cup has 1/30 the thermal energy of the liquid in the urn. The liquid in the urn has 30 times the thermal energy of the liquid in the cup

Question: Draw Conclusions What is a major NATURAL source of thermal energy on Earth?

The Sun!!! The sun is our BFF

What’s the main idea of this lesson? Everyone should know this by now…

How thermal energy spreads!!! You are so smart!!!

Let’s read about conduction and convection on PP. 338 and 339 Who would like to volunteer to read first?

Question on conduction… How is heat transferred between two materials in conduction?

Question on conduction… Rapidly vibrating particles in one material cause nearby particles in the other to vibrate rapidly.

Question on convection… Why does water that has been heated rise to the top of an aquarium?

Question on convection… As it heats up, it expands and becomes less dense; less dense water rises.

Question… Critical Thinking Does conduction always require a medium for heat to pass through?

Question… Critical Thinking Yes. In conduction, heat passes through a solid of some sort, so conduction must occur in a medium.

Let’s talk “Radiation” Who’d like to begin reading on P. 340?

Think about what we just read… What kind of electromagnetic waves are commonly called heat waves?

Think about what we just read… One with infrared wavelengths

Think about what we just read… What color clothes are better in hot weather? (Better for staying cooler). Why?

Think about what we just read… Light-colored clothes, because they reflect more of the energy of visible light than they absorb.

Visual Summary Let’s copy the visual summary chart on P. 341 in our science journals. Then we will discuss it as a class.

What have we learned in this lesson? Name and describe the three ways that thermal energy is transferred.

What have we learned in this lesson? Conduction - between two touching solids Convection – liquids and gases Radiation - waves

What have we learned in this lesson? What is the difference between conduction and convection?

What have we learned in this lesson? Conduction = thermal energy passes from particle to particle Convection = passes through a moving medium

What have we learned in this lesson? Why do some materials make good conductors while others make good insulators?

What have we learned in this lesson? Materials with molecules arranged close together = good conductors Materials with loosely organized molecules = good insulators

What have we learned in this lesson? How could you determine if a material is a conductor or an insulator?

What have we learned in this lesson? Place it near a heat source and measure the increase in its temperature.

What have we learned in this lesson? Infrared rays emitted by a fire are an example of: A radiation B convection C insulation D conduction

What have we learned in this lesson? Infrared rays emitted by a fire are an example of: A radiation B convection C insulation D conduction

There will be a test over Chapter 9 Use pp. 346 and 347 as your study guide.