Energy and Energy Resources

About the

Imagine that youre a driver in this race. Yourcar needs a lot of energy to nish. So, itprobably needs a lot of gasoline, right? No, itjust needs a lot of sunshine! This car runs onsolar energy. Solar energy is one of the manyforms of energy. Energy is needed to drive acar, turn on a light bulb, play sports, and walkto school. Energy is always being changedinto different forms for different uses.

Layered Book Beforeyou read the chapter, createthe FoldNote entitled Lay-

ered Book described in the Study Skillssection of the Appendix. Label the tabs ofthe layered book with Types of energy,Energy conversions, Conservation ofenergy, and Energy resources. As youread the chapter, write information youlearn about eachcategory under theappropriate tab.

SECTION

Energy can be changed fromone form into another form,but energy cannot be createdor destroyed.

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9

Chapter 9

1 What Is Energy? . . . . . . . . . . . . 240

2 Energy Conversions . . . . . . . . . 248

3 Conservation of Energy . . . . . 254

4 Energy Resources. . . . . . . . . . . 258

START-UPSTART-UP

Energy and Energy Resources

Energy Swings! In this activity, youll observe a moving pendulum to learn about energy.

Procedure1. Make a pendulum by tying a 50 cm long string

around the hook of a 100 g hooked mass.

2. Hold the string with one hand. Pull the mass slightly to the side, and let go of the mass without pushing it. Watch it swing at least 10 times.

3. Record your observations. Note how fast and how high the pendulum swings.

4. Repeat step 2, but pull the mass farther tothe side.

5. Record your observations. Note how fast and how high the pendulum swings.

Analysis1. Does the pendulum have energy? Explain your

answer.

2. What causes the pendulum to move?

3. Do you think the pendulum had energy before you let go of the mass? Explain your answer.

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