Chapter 8, Lesson 3, "Energy"
Drip development and use of the Power formula.:*Remind the students of the Mr. Incredible and Dash problem. Who was more powerful? Show them the poblem and go through it again. Mr. Incredible can push with a force of 5000N on a train an move it 100 meters. While Dash can push this tiny railcar with a force of 50N 100meters. Show the students a separate problem, give the students 3-4 minutes to work on the problem and then go through the problem with them.
Anticipatory Set:* Students will take a look at three things, a radio, a flashlight, and a hair dryer. The students will describe what kind of energy these items all turn electrical energy into. Next they will be shown a match. Students will be told that in this match there is a stored energy. That energy is in the form of a chemical energy. Light the match and ask the students what kind of energy is being released from the chemical energy that was within the match. Ask the students to name some other things that can store energy.
Teacher Input:* I think we all know energy when we see it, but what is a good definition of energy? It is pretty easy to see that wind does work on objects. A hammer hitting something can move the object and do work. Running water can move water wheel 2 things. A moving car can move anther if it runs into a stopped car. All of these things have an energy that is in motion. That energy has a special name, Kinetic Energy.
At the beginning of the lesson we talked for a second about match and how it has a stored chemical energy in it. Is there anything else you can think of that stores energy? ( battery, stretched rubber band, a set trap, water behind a dam, a stretched bow, gasoline, and even the ground beneath your feet, earthquake) All of these things have a different types of energy called Potential Energy.
Show an animation of a pendulum. Stop the animation several times and ask if there is more potential or kinetic energy at each point. Show several animations, pendulum, kinetic, potential.
Show this picture and ask what kind of energy is being shown in each box.
There are several several forms of energy we use today. Students will want to develop a table in their notes with three columns. The first smaller column for the form of energy and the second is an example of that energy, and the third for a description of that energy. Something like the table below.
|Form of Energy||Example of this Energy||Description of that energy|
|Chemical Energy||Food||energy stored in the bonds between atoms or being released as the bonds break.|
|Heat Energy||Steam||molecules within a substance are moving faster.|
|Mechanical energy||a falling rock||energy in moving objects|
|Nuclear energy||plutonium||energy is release as the nucleus of an atom changes|
|Radiant energy||Sun||type of light energy associated with photons|
|Electrical energy||a generator||Electrons are set in motion and that energy is usually changed into other types of energy to use.|
All these types of energy can be changed from to another. You may use electrical energy to create heat. You may use heat energy to create mechanical energy like in a power plant with then creates electrical energy again. You may use chemical energy to create heat energy. You may use nuclear energy to create electrical energy. There is really no limit on how you can transfer energy from one form to another. However, each transfer usually causes some energy to be lost to the environment. For example if you use heat energy to create steam some heat is lost to the environment. Then if you use heat energy from steam to turn a turbine and get mechanical energy some energy is lost. If you then use that mechanical energy to create electrical energy some energy is again lost to the environment in this case mostly through friction. So.. you would not want to use electrical energy to try and generate more electrical energy because you would get far less out than you put in.
It is important to note that the energy being lost in the transformations is not destroyed. It is being lost to the environment. In fact there is a Law that states energy cannot be created or destroyed. What is the name of that law? Lets look back at a book falling from a table. As the book falls its potential energy decreases, its kinetic energy increases. When it hits the floor, its energy is changed into mechanical energy in the form of sound and movement of anything hit by the book, and some heat energy. No energy is lost. We see this on a roller coaster. A roller coaster is lifted to its highest point and it has a lot of potential energy. Then when it goes down potential energy decreases and the kinetic energy increases. Then it travels up the next hill its kinetic energy decreases and its potential energy increases. However some energy is lost to the environment along the way. How? (sound, mechanical; heat; friction) Engineers are constantly trying to reduce friction in moving objects so that they get the most energy transfer and make the machine much more efficient. Does anyone know what type of vehicle is being use that has virtually no friction between the vehicle and the service it is traveling on? (magnetic train)
Guided Practice:* Students will take turns answering the questions from Page 215.
Drip the Atom and Periodic Table:* Ask the students what the basic building block of all matter is. We are going to try something that is similar to yesterday but this time we are going to work as groups to help each other. Each site will be assigned a picture. The need to write down a little description of the picture over a period of 5 minutes. then they will share the description with the other sites. Here are the pictures: Atom, Atom charges, Periodic table, symbol, Water Molecule, Salt Molecule; All.
Independent Practice:* Students will read Lesson 3, "Energy" Pages 211-215. Students will also complete the worksheet, "Energy"
Check for Understanding:* Students will take the test on Chapter 8 Lesson 3, "Energy"
30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).
Alaska Content Standards Addressed in this lesson: