Lesson 1.2 - Forms of Energy: Then and Now

How has the use of energy changed in the last 100 years?  How is energy the same now as it was 100 years ago? 

Read Starting Point Activity on page 237 and Find Out Activity on page 239.

Two other important forms of energy were not mentioned in the assigned reading:

  • Kinetic energy is the energy due to the motion of an object.  Anything that moves has kinetic energy.  Kinetic energy is sometimes called mechanical energy. 
  • Potential energy is the energy stored in a substance.  There are various forms of potential energy: chemical potential energy (which is just called chemical energy) and the potential energy due to position.  For example, if you lift a book from your desk and hold it above the desk, it has potential energy.  If you drop the book to the desk, it will make noise when it hits the desk, and it could break something if it landed on it. 

Now, answer the following questions.

 

Question 1. What are five forms of energy listed in Find Out Activity on page 239?

Question 2. What are two other forms of energy that were discussed?

Question 3. Look at the two pictures in Find Out Activity on page 239.  Try to find at least one example of each form of energy and tell where the energy is found or used.

Question 4. The two farming pictures on pages 236 and 237 show two types of energy used to plow land.  What are the forms of energy in each picture?

Question 5. What is the source of energy for everything in all four pictures?

Question 6. Many energy conversions must be happening in the pictures.  List as many energy conversions as you can.

Question 7. Answer question 1 in Check Your Understanding on page 239.

 

Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. What are five forms of energy listed in the "Find Out Activity" on page 239?

The five forms of energy listed are

        • light
        • chemical
        • thermal (heat)
        • electrical
        • sound  

Question 2. What are two other forms of energy that were discussed?

Two other forms of energy that were discussed were kinetic energy and potential energy.

Question 3. Look at the two pictures in Find Out Activity on page 239.  Try to find at least one example of each form of energy and tell where the energy is found or used.

Picture of the farm in 1915:

          1. Light:  The sun must be shining because the picture was taken.
          2. Chemical:  There is chemical energy in almost everything in the picture; chickens, grain, people, horse, wood.
          3. Thermal:  The air must be warm because they are not dressed very warmly and there is no snow on the ground.  All the animals have thermal energy in their bodies.
          4. Electrical:  There is no evidence of electrical energy.
          5. Sound:  You can assume the chickens and people are making sounds.
          6. Kinetic Energy:  You can assume the people and animals are moving, there might be a wind blowing.
          7. Potential Energy:  The child on the horse has potential energy; anything that can fall down has potential energy.

Picture of the modern feedlot:

          1. Light:  The sun must be shining because the picture was taken.
          2. Chemical:  There is chemical energy in almost everything in the picture; cattle, food, wood.
          3. Thermal:  The air must be warm since there is no snow on the ground.  All the cattle have thermal energy in their bodies.
          4. Electrical:  There is no evidence of electrical energy.
          5. Sound:  You can assume the cattle are making sounds.
          6. Kinetic Energy:  You can assume the cattle are moving; there might be a wind blowing.
          7. Potential Energy:  Anything that can fall down has potential energy.

Question 4. The two farming pictures on pages 236 and 237 show two types of energy used to plow land.  What are the forms of energy in each picture?

The first picture shows horses pulling a plow.  The form of energy used is "horse power" or "animal power".  The food that the horses eat is converted to energy by the muscles.  The second picture shows a tractor pulling a plow.  The form of energy used by the tractor is likely diesel fuel, which is derived from oil (petroleum).  The energy in the fuel was stored by plants and animals millions of years ago.  

Question 5. What is the source of energy for everything in all four pictures?

The source of energy for everything in all four pictures is the sun. 

Question 6. Many energy conversions must be happening in the pictures.  List as many energy conversions as you can.

Here are some examples:

          1. Light:  The sunlight is converted to heat; then, it is stored as chemical energy in the food, wood, and bodies of the animals.
          2. Chemical:  The chemical energy in the food is converted to kinetic energy in the moving animals, heat in their bodies, and to sound.
          3. Thermal:  The heat in the air is converted to kinetic energy as the air moves in convection currents.
          4. Sound:  The sounds are converted to kinetic energy in the ears of the animals.
          5. Sound:  You can assume the cattle are making sounds.
          6. Kinetic Energy:  You can assume the cattle are moving; there might be a wind blowing.
          7. Potential Energy:  Anything that can fall down has potential energy.

Question 7. Answer question 1 in the Check Your Understanding on page 239.

          1. Energy does not have mass and does not take up space.
          2. Energy cannot be created or destroyed.
          3. Energy can be transformed from any form to any other form.
          4. Energy can be transferred from one object to another object. 

 

Now, do Assignment 12A.  Page forward to access it.

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