Applications of Energy to The Real World

1. Applications of Energy to The Real World A TAKS Tutorial

2. Energy causes Change • The sunradiates light and heat energy. • At night, street lights convert electrical energy to light. • As a car drives by, it is making power from gasoline - stored energy. • Our bodies eat food, which converts chemical potential energy to the kinetic energy we need to play or study. • Energy makes everything happen. • Energy is the ability to do work.

3. Energy can be divided into two main types: • Energy that is stored is called potential energy,(energy of position or condition). • Energy that is moving is called kinetic energy, (energy of motion).

4. How is Energy Measured? • Energy can be measured in joules (pronounced the same way as the word jewels). • 1,000 joules = 1 Btu • 1,000 joules = 1 kilojoule = 1 Btu • It would take 2 million joules to make a pot of coffee. • One joule is the amount of energy needed to lift one pound about nine inches.

5. Where did the unit “Joule” come from? • The "Joule" is named after an English physicist named James Prescott Joule who lived from 1818 to 1889. • He discovered that heat is a type of energy.

6. How can we use energy? • A piece of buttered toast contains about 315 kilojoules of energy. With that energy you could: • Jog for 6 minutes • Bicycle for 10 minutes • Walk briskly for 15 minutes • Sleep for 1-1/2 hours • Run a car for 7 seconds at 80 kilometers per hour (about 50 miles per hour) • Light a 60 watt light bulb for 1-1/2 hours

7. Energy changes from one form to another • Stored energy in a flashlight's batteries becomes light energy when turned on. • Food contains energy stored as chemical potential energy. Your body uses the stored energy to do work. • If you overeat, the food's energy is stored as potential energy in fat. • When you talk on the phone, your voice is changed to electrical energy. The phone on the other end changes the electrical energy into sound energy.

8. Heat is a form of energy • We use it for a lot of things like warming our homes and cooking our food. • Heat energy is transferred in three ways: • Conduction • Convection • Radiation

9. What is Conduction? • Conduction occurs when energy is passed from one object to another by contact. • Metals are excellent conductors of heat energy. Other things like wood or plastics are not good conductors of heat energy. Poor conductors are called insulators.

10. What is Convection? • Convection is the movement of fluids (gases or liquids) from a cooler place to a warmer one. • Wind is often caused by convection currents that occur as, cool air over water moves to replace warm air over land which then rises. • During the night time, the direction changes and the water loses its heat slower as the land cools faster.

11. What is Radiation? • Radiation is also a form of heat energy transfer. • Energy waves transfer sunlight to the earth, traveling in straight lines. • When the sun light hits the earth, the radiation is absorbed by the water or land or it can be reflected . • In general darker surfaces absorb more radiation than lighter surfaces, which reflect more radiation. • Wearing light or white clothes outside during the summer will reflect more of the sun’s energy.

12. Energy Self Quiz: 1. Energy is: a) The ability to store molecules b) the ability to do work c) can be transferred to other forms d) a and c are correct 2. There are: a) two main types of energy b) three main types c) neither of these is correct 3. Kinetic energy is: a) energy in motion b) energy at rest c) chemical energy d) none of these 4. Potential energy: a) energy in motion b) energy at rest c) stored energy d) all of these 5. Energy is measured in units called the: a) Joule b) Prescott c) Maxwell d) none of these

13. Answers to the Self Quiz: 1. d) a and c are correct 2. a) two main types of energy 3. a) energy in motion 4. c) stored energy 5. a) Joule