You may have learned that energy is the "ability to do work or cause change." Energy exists in a variety of forms. Heat, light, sound, or motion are sure signs that some form of energy is present and being used.

Moving objects have what is called mechanical (meh-CAN-ih-cul) energy. Mechanical means produced by or relating to a machine. A car driving along a road or an airplane in flight are examples of machines that have mechanical energy.

But any object that is in motion or raised above the ground also has mechanical energy: think of a ball flying through the air or a piece of fruit on a table. In this lesson, you will learn how mechanical energy makes things move.

Write down three other objects that have mechanical energy.

Goals
Here are the big ideas you will learn about in this lesson:

• Energy can change from one form to another.
• The transfer of energy causes objects to move.
• Whenever energy decreases in one part of a system, it increases by the same amount in other parts of the system.

Strategies
You will be using many reading and writing strategies to complete this lesson. The key strategies that you will focus on are:

• Using background knowledge
• Determining important information
• Identifying and using text features
• Constructing summaries

• kinetic
• potential
• transfer

Roller coasters are designed to run on two basic scientific principles: 1) gravity and 2) the transfer of energy. On Earth, gravity is the force that pulls objects toward the ground. The transfer of energy is what causes objects at rest to move and objects in motion to slow or stop. Roller coasters move along a track as energy changes form and is transferred into and out of the cars.

In this video, you will meet Chris Gray, a mechanical engineer. Mechanical engineers use their knowledge of science to design, make, and maintain all kinds of machines. Watch the video to see what Chris says about the changes in energy that create the excitement in riding a roller coaster.

Click "View" on the left to watch the video.

After watching the video, write one to two sentences explaining what causes a roller coaster to move.

The mechanical energy in a moving object is the combination of potential (puh-TEN-shul) energy and kinetic (kih-NEH-tik) energy. Potential energy—often referred to as stored energy—is energy of position, and kinetic energy is energy of motion.

When engineers design a roller coaster, they must create the greatest amount of potential energy at the beginning of the ride. This is because after the start, the cars will move under their own power to the finish. Engineers have a motor pull the cars to the highest peak—where potential energy is greatest—very early in the ride and then allow the force of gravity to keep the cars moving.

As the cars start to descend (fall) down the track, the potential energy converts (changes) into kinetic energy. At the bottom of the first hill, kinetic energy is greatest, and this drives the cars up the next hill. The roller coaster cars, the track, the motor that drives the chain that pulls the cars uphill, and Earth’s gravity all work together as a system in which energy changes from one form to another.

The change in form between potential and kinetic energy continues throughout the roller coaster ride. Each time the cars ascend (climb) a hill, some kinetic energy converts into potential energy. Then, some of this potential energy converts back each time the cars descend.

In this interactive activity, a pie chart shows how energy changes back and forth between potential energy and kinetic energy throughout a ride. Click "View" on the left to begin. Click "Play" to view the full ride once. Then click "Step" to review each part of the ride to see the changes between potential and kinetic energy.

At what point on the roller coaster ride is there the greatest amount of potential energy? At this same spot, what is the amount of kinetic energy? Write one to two sentences to explain your answers.

Now you will read about some of the factors that engineers must consider when designing a roller coaster track.

Click "View" on the left to open the reading passage.

After reading the passage:

• Name one factor that determines how much potential energy there is in a roller coaster ride.
• Name one factor that affects how much total energy roller coaster cars contain during a ride.

The videos you have seen and the text you have read explored how energy can change from one form to another.

Now show what you have learned so far about energy transfer in a roller coaster ride and how forces influence roller coaster design by answering these three questions. Be sure to save all your answers before you go to the next screen.

You will now check your understanding of the vocabulary words for this lesson by placing them in sentences. Click "View" on the left to begin the activity.

Before moving to the next screen, choose two words from the vocabulary list and write a new sentence for each word.

Vocabulary words: ascend, descend, friction, gravity, kinetic, potential, transfer

In this activity, you will read more about the transfer of energy within a roller coaster ride. You will then highlight parts of the passage to answer two related questions.

• How are the different types of energy present in a roller coaster ride measured?
• How does energy change form during a roller coaster ride?

Click "View" on the left to begin the activity. Your teacher will review the answers with you.

Before moving on to the final assignment, you may want to reread the passage, review this lesson's video, or try the interactive activity again.

Putting Energy to Work

Document

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Roller Coaster Design

Video: 0m 53s

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Energy in a Roller Coaster Ride

Interactive

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In this lesson, you have learned how energy changes form as roller coaster cars move along a track. You have also learned that engineers design roller coasters and other mechanical devices using their understanding of the transfer of energy. You will now write an essay that shares what you have learned and what you think about it.

Begin by reviewing your notes. Click "review my work" above and view or print out the screen that pops up.

Final Assignment Instructions

• Click Energy Transfer in a Roller Coaster—Final Assignment (PDF).
• Choose one of the topics in the PDF and write an essay.
• Organize your response so that it includes at least three supporting details that you have learned from the reading passage, video, interactive activity, and other materials in this lesson.
• Use at least three vocabulary words (or a form of the words) as part of your supporting details. For example, for the word jump, you could use jumps, jumped, or jumping.