1. introduction to energy powerpoint

Type of Energy Sources

1. EE 40403 – Energy Management Energy Management Rantharu Attanayake BSc. ( Eng ) , MSc, MBA Email : [email protected] Mobile : [phone]

2. Introduction to Energy Types and Forms EE 40403 – Energy Management

3. Objectives Explain what energy enables us to do. Differentiate between forms and sources of energy. Demonstrate how energy is stored in the major energy sources. EE 40403 – Energy Management

4. Energy Energy exists in many forms. Energy can be moved from one object to another. Energy can be changed from one form to another. Energy cannot be created or destroyed.

5. Energy in two Forms Potential Energy and Kinetic Energy Potential Potential Energy has 4 forms: Chemical energy   Nuclear energy   Gravitational energy   Elastic energy The energy in matter due to its position or the arrangement of its parts One of the most common equations for potential energy can be used to determine the energy of an object with respect to its height above a base: E = mgh ( Joule)

6. Energy in two Forms Kinetic Kinetic Energy has 5 forms: Mechanical energy   Electrical energy Thermal energy Radiant energy   Sound energy   The energy of a moving object A common formula for kinetic energy is for a moving mass: KE = 1/2 mv 2 (Joule)

7. Law of Conservation of Energy With every transformation, some energy is converted to less useful forms. Energy conversions are not 100% efficient. The energy output for the intended purpose is seldom the same as the energy we put in. 100 J electricity in 95 J heat out 5 J light out While energy can change forms, it is conserved. In other words, the total energy  of a system  is a constant value. This is often written in terms of kinetic (KE) and potential energy (PE): KE + PE = Constant

8. Gravitational Energy The energy an object or substance has because of its position; anything “up high” Potential Energy

9. Stored Mechanical Energy Energy stored in an object by the application of force Must push or pull on an object Potential Energy

10. Potential Energy Nuclear Energy Energy contained in the nucleus of an atom Nuclear energy is released when nuclei are split apart into several pieces, or when they are combined to form a single, larger nucleus

11. Chemical Energy Energy released by a chemical reaction The food you eat contains chemical energy that is released when you digest your meal Wood, coal, gasoline, and natural gas are fuels that contain chemical energy Potential Energy

12. Mechanical Energy (Motion) Energy that moves objects from place to place You use mechanical energy when you kick a ball or turn the pedals of a bicycle Other examples include water flowing in a stream, tires rolling down a road Kinetic Energy

13.   Electrical Energy Energy that comes from the electrons within atoms It can be generated at a power plant or inside a battery and can power everything from remote-controlled cars to refrigerators Lightning and static electricity are also forms of electrical energy Kinetic Energy

14. Sound Energy Movement of energy through substances in the form of longitudinal (compression) waves Kinetic Energy

15. Radiant Energy Electromagnetic energy that travels in transverse waves Energy that can move through empty space The sun and stars are powerful sources of radiant energy The light given off by light bulbs and campfires are also forms of radiant energy Kinetic Energy

16. Kinetic Energy Thermal Energy Internal energy of a substance due to the vibration of atoms and molecules making up the substance

17. Elastic energy Mechanical energy  

18. Striking a match Photovoltaic cell Photosynthesis Interior temperature increase of a car Describe the Energy Transformations

19. Transition: Forms to Sources chemical chemical chemical chemical chemical nuclear motion motion thermal radiant

20. Transition: Forms to Sources 86% 9% 5% 1% 1% 89% 11%

21. Potential Energy and Kinetic Energy Examples PE =m g h =2 kg × 9.8 m/s 2  × 0.4 m =7.84 kg m 2 /s 2 = 7.84 J Example: This 2 kg hammer is 0.4 m up. What is it's PE?

22. Potential Energy and Kinetic Energy Examples KE = ½ m v 2 KE = ½ × 1500 kg × (14 m/s) 2 KE = 147,000 kg m 2 /s 2 KE =  147 kJ Example: What is the KE of a 1500 kg car going at suburban speed of 14 m/s (about 50 km/h or 30 mph)?

23. Potential Energy and Kinetic Energy Examples KE = ½ m v 2 KE = ½ × 1500 kg × (28 m/s) 2 KE = 588,000 kg m 2 /s 2 KE =  588 kJ Example: The same car is now going at highway speed of 28 m/s (about 100 km/h or 60 mph)?

24. Potential Energy and Kinetic Energy Examples KE = ½ m v 2 KE = ½ × 1 kg × (11,000 m/s) 2 KE = 60,500,000 J KE = 60.5 MJ A 1 kg meteorite strikes the Moon at 11 km/s. How much KE is that?

25. Potential Energy and Kinetic Energy Examples At 1 m above the ground it's Potential Energy is PE = m g h PE = 0.1 kg × 9.8 m/s 2  × 1 m PE = 0.98 kg m 2 /s 2 Ignoring air resistance (which is small for this little drop anyway) that PE gets converted into KE: KE = ½ m v 2 Swap sides and rearrange: ½ m v 2  = KE v 2  = 2 × KE / m v = √( 2 × KE / m ) Now put PE into KE and we get: v = √( 2 × 0.98 kg m 2 /s 2  / 0.1 kg ) v = √( 19.6 m 2 /s 2  ) v = 4.427... m/s Example: We drop this 0.1 kg apple 1 m. What speed does it hit the ground with?