Unit 13 Lesson 2: Heat Energy


Believe it or not, the concept of heat is really a bit tricky. What we call heat in common language, is really not what heat is as far as physics goes. Heat, in a way, doesn’t exist. Nothing has heat. Things can have a temperature. They can have a thermal energy but they can’t have heat. Heat is really the transfer of thermal energy. Or, in other words, the movement of thermal energy from one object to another. Confused yet? Let’s get started with this video:



In this lesson, we are going to learn what heat is and how it moves from place to place. You know how they say, “If you can’t stand the heat, get out of the kitchen.”? Well after this lesson you’ll know exactly what it is that you can’t stand!


Believe it or not, the concept of heat is really a bit tricky. What we call heat in common language, is really not what heat is as far as physics goes. Heat, in a way, doesn’t exist. Nothing has heat. Things can have a temperature. They can have a thermal energy but they can’t have heat. Heat is really the transfer of thermal energy. Or, in other words, the movement of thermal energy from one object to another.


Scientific Concepts:

  • Heat is the movement of thermal energy from one object to another.
  • Heat can only flow from an object of a higher temperature to an object of a lower temperature.
  • Heat can be transferred from one object to another through conduction, convection and radiation.
  • Conduction is the wiggle and bump method of heat transfer. Faster moving molecules bump into slower moving molecules speeding them up. Those molecules then bump into other molecules speeding them up and so on increasing the temperature of the object.
  • Convection is heat being transferred by currents of moving gas or liquid caused by hot air/liquid rising and cold air/liquid falling.
  • Radiation is the transfer of heat by electromagnetic radiation, specifically infra-red radiation.
  • Heat is movement of thermal energy from one object to another.
  • When an object absorbs heat it does not necessarily change temperature.
  • As objects change state they do not change temperature.
  • The heat that goes into something as it’s changing phases is used to change the “bonds” between molecules.
  • Objects release heat as they freeze and condense.
  • Objects absorb heat as they evaporate and melt.
  • Freezing points, melting points, boiling points and condensation points are the “speed limits” of the phases. Once the molecules reach that speed they must change state.
  • Heat capacity is how much heat an object can absorb before its temperature increases.
  • Specific heat is how much heat energy a mass of a material must absorb before it increases 1°C.
  • Heat capacity is influenced by the specific heat of the material and/or the amount of the material.
  • Each material has its own specific heat. The higher a material’s specific heat is, the more heat it must absorb before its temperature increases.
  • A larger amount of something will have a higher heat capacity then a smaller amount of something.
  • Water has a very high heat capacity.

Lessons:

Fire-Water Balloon
If you’ve ever had a shot, you know how cold your arm feels when the nurse swipes it with a pad of alcohol. What happened there? Well, alcohol is a liquid with a fairly low boiling point. In other words, it goes from liquid to gas at a fairly low temperature. The heat from your […]
Convection Currents
Every time I’m served a hot bowl of soup or a cup of coffee with cream I love to sit and watch the convection currents. You may look a little silly staring at your soup but give it a try sometime! Convection is a little more difficult to understand than conduction. Heat is transferred by […]
Solar Drinking Bird
The Drinking Bird is a classic science toy that dips its head up and down into a glass of water. It’s filled with a liquid called methylene chloride, and the head is covered with red felt that gets wet when it drinks. But how does it work? Is it perpetual motion? Let’s take a look […]
Hero Engine
There are lots of different kids of heat engines, from stirling engines to big jet turbines to the engine in your car. They all use clever ways to convert a temperature difference into motion. Remember that the molecules in steam move around a lot faster than in an ice cube. So when we stick hot […]
Peanut Energy
This experiment is for advanced students. Did you know that eating a single peanut will power your brain for 30 minutes? The energy in a peanut also produces a large amount of energy when burned in a flame, which can be used to boil water and measure energy. Peanuts are part of the bean family, […]
Soaking Up Rays
Heat is transferred by radiation through electromagnetic waves. Remember, when we talked about waves and energy? Well, heat can be transferred by electromagnetic waves. Energy is vibrating particles that can move by waves over distances right? Well, if those vibrating particles hit something and cause those particles to vibrate (causing them to move faster/increasing their […]
Stirling Engine
This project is for advanced students.This Stirling Engine project is a very advanced project that requires skill, patience, and troubleshooting persistence in order to work right.  Find yourself a seasoned Do-It-Yourself type of adult (someone who loves to fix things or tinker in the garage) before you start working on this project,  or you’ll go […]