Presentation Transcript

1. Energy Transformation and the Law of Conservation of Energy

2. Energy Energy is capacity to do work.The international measurement system for energy is named "Système International d'Unités" (french abbreviation: SI). The international recognized unit for energy is the Joule (J), named after James Joule. He was the scientist who for the first time demonstrated the rule that work can be converted into heat. Work is a force applied to an object over a certain distance, such as pulling or pushing a wooden block across your desk. Your muscles do work when they facilitate body movement. Any form of energy can be transformed into another form. This is called energy transformation or energy conversion. Energy doesn't disappear - just changes the forms. Energy transformation is the process of changing energy from one form to another. This process is happening all the time
3. The Main Energy Forms Electromagnetic energy (travels through space) chemical energy mechanical energy nuclear energy electrical energy heat (thermal) energy energy of sound
4. Electromagnetic Energy The energy of electromagnetic waves, is also known as radiant energy. The sun gives off electromagnetic energy in the forms of waves. The waves have both electrical and magnetic properties.
5. Chemical Energy Chemical energy is a potential energy. It comes from the bonds of atoms and molecules. Example: people utilize the chemical energy from the food they consume, and their body transforms it into mechanical energy, that allows them to run, play games, do work and etc.
6. Chemical Energy Chemical energy is a potential energy. It comes from the bonds of atoms and molecules. Example: people utilize the chemical energy from the food they consume, and their body transforms it into mechanical energy, that allows them to run, play games, do work and etc.
7. Mechanical Energy Form of energy associated with the position and motion of an object A quarter back football player transfers motion to a football An object with mechanical energy can do work on another object. The more mechanical energy the object has, the more work it can do. Formula: ME=PE+KE
8. Nuclear Energy Nuclear Energy (atomic energy) is the energy stored in the nucleus of an atom. That energy can be released when we combine (energy fusion) or split (energy fission) the nuclei.
9. Electrical Energy The energy of electric charges (electrons) Can be potential or kinetic An example of kinetic is lightening An example of potential is a battery
10. Thermal energy Thermal energy (heat energy) is the total kinetic energy of atoms and molecules that are constantly in motion. It’s the motion of molecules.
11. Sound Energy Sound energy (energy of the sound) is a type of wave motion. When we talk we breathe out that occurs the effect of air motion which is because the air molecules are vibrating. The vibrating molecules hit our eardrums. That allow us to hear when we talk. Sound energy is possible to be converted into electrical energy and to transmit from one place to another - good example for it is the radio, phone.... After that this electric energy could be transformed back to sound energy that we can hear.
12. Energy Types Energy type is different than energy form. All energy forms could be set as two types of energy - potential and kinetic energy Kinetic energy is the motion. Potential energy is the stored energy.
13. Energy Transformation Energy transformation is the process of changing energy from one form to another. This process is happening all the time. Any form of energy can be transformed into another form. This process of energy transformation is also known as energy conversion.
14. Energy Transformation Examples Energy Transformation is happening all of the time. Energy of food could be transformed in energy to play. Chemical energy from coal, oil, natural gas can be transformed into heat energy (process of burning the fuel). The heat energy can be converted into kinetic energy by gas turbines or into electrical energy by generators; or it might be expelled into the atmospere.
15. Energy Transformation Examples (Cont’d) Sun gives the grass thermal energy. The grass uses it to grow and transform it to a chemical energy using the photosynthesis process. Rabbits eat grass and use it as an energy source to grow and to have power to run. Hunting dogs like rabbits, but they can run after them only if they have enough power to do that. To have power dogs need to be feed.
16. Energy Transformation Examples (cont’d) If you turn on the power switch the electricity bulb will use the electricity power and will transform in to light. The wind turbine uses the wind energy and transforms in to electricity. Solar panels transform light to electricity.
17. Where else can we find examples of Energy Transformation? Look around you and try to find other examples for energy transformation.
18. Energy Transformation and the Law of Conservation of Energy Work is an energy requiring process. So, how do you describe energy? Energy is not a substance that can be held, seen, or felt as a separate entity. We cannot create new energy that is not already present in the universe. We can only take different types materials in which energy is stored, change their state, and harness the energy that escapes from the system in order to use it to do work for us. If the released energy is not used, it will escape and be transformed usually as heat.
19. Law of Conservation of Energy Energy doesn't disappear - it just can change forms. Energy is not destroyed or created – it can just change forms or remain the same. The total amount of energy always stays the same. If 100% energy is put into any system or task, 100% energy will come out either in it’s original form plus a new form as multiple different energies, or it will come out as 100% energy in a new form. The Law of Conservation of Energy states that the total amount of energy in the universe is constant. This means that all of the energy has to end up somewhere, either in the original form or in a different form.
20. Law of Conservation of Energy (cont’d) We can use this knowledge to determine the amount of energy in a system, the amount lost as waste heat, and the efficiency of the system. Heat is the quantity of energy stored or transferred by thermal vibrations of molecules. At absolute zero (approx. -459 degrees Celsius), a system has no heat energy. Heat is additive. If two masses with heat energies of 5 joules and 10 joules are added together, the added masses will have a total heat energy of 15 joules. Heat and temperature should not be confused.
21. Law of Conservation of Energy (cont’d) We can use this knowledge to determine the amount of energy in a system, the amount lost as waste heat, and the efficiency of the system. Heat is the quantity of energy stored or transferred by thermal vibrations of molecules. At absolute zero (approx. -459 degrees Celsius), a system has no heat energy. Heat is additive. If two masses with heat energies of 5 joules and 10 joules are added together, the added masses will have a total heat energy of 15 joules. Heat and temperature should not be confused.
22. Law of Conservation of Energy (cont’d) The temperature of a system is the average vibrational energy of all the molecules within the system. Temperature is not additive. Putting two metal blocks that are 75o C together will leave the new system at the same temperature; whereas if you’re talking about heat, the total energy would be 150o C. Putting two masses that are 50o C and 100o C will make the new system somewhere between 50o C and 100o C. The temperature of which would be dependent on the masses and heat capacities of each added element. When a fast-moving molecule collides with other molecules, it loses some of its kinetic energy to those surrounding molecules. Those molecules now have more energy than they had before. This extra energy is manifested as vibrations within the molecule. Thus, the temperature of the substance being hit will increase. For example, when ice cream melts, warmer molecules from the surrounding air infuse the ice cream, collide with the colder molecules, and the colder molecules speed up due to collissions with the warmer molecules, and this causes the ice cream to melt.
23. Law of Conservation of Energy (Cont’d) We’re going to look at the transformation of energy and the Law of Conservation of Energy by using an example of an internal combustion engine. Combustion is where a chemical change takes place when something is burned or oxidized. Combustion produces heat and usually light. Internal means inside—so internal combustion means a chemical change is taking place due to burning, inside a chamber. Internal combustion engines are machines that enable other machines or parts of a machine to do work. Internal combustion engines are found inside automobiles, tractors, go-carts, or anything operated by gasoline.
24. Law of Conservation of Energy (cont’d)
25. Law of Conservation of Energy (Cont’d) An example of how an internal combustion engine works is in this video: http://www.sciencekids.co.nz/videos/engineering/carengine.html
26. Law of Conservation of Energy (cont’d) Internal combustion engines work this way: Into a chamber, a small amount of fuel is drawn. The fuel is ignited (set on fire), by a spark plug, and this causes a small explosion in the chamber. The explosion (combustion), is what gives the engine power to move parts attached to the chamber. There are hundreds of parts used in engines to make it function well enough to work for many years. When we look at an internal combustion engine, it can give us a great insight both concepts of transformation of energy and the law of conservation of energy (also known as the first law of thermal dynamics). When an internal combustion engine is running, it uses gasoline, a fuel, and the fuel is combined with oxygen and a flame by the spark plug to produce a very small explosion. This explosion produces power which enables the engine to move cam shafts, axles, gears pulleys and other parts of the vehicle.
27. Law of Conservation of Energy (cont’d) The next video shows the computer generated assembly of an engine, and how all of the parts work together. https://www.youtube.com/watch?v=l7MUL3vtZ5o
28. How does an engine an example of energy transformation and the law of conservation of energy? Energy Transformation: No energy is ever lost, it it only stays as it is, or it is transformed into different forms of energy. In the case of an internal combustion engine: Potential chemical energy (the fuel), is put into a chamber (container) of the engine. The fuel is ignited (set on fire) in the chamber, and when that happens, the potential chemical energy changes to kinetic energy (during combustion); and then the explosion of the chemical change causes engine parts to move. The rest of the car parts move because the engine powers the other car parts through a system of pulleys, gears and levers. No energy is ever lost, it just remains in its original form or is transformed.
29. Law of Conservation of Energy (cont’d) No energy is ever lost, it just remains form or is transformed. In every energy transformation, energy is conserved. This means that the form of energy may change as it is used, but the amount of energy is always 100%. 100% is input, and 100% is output. According to the Law of Conservation of energy, The total sum of potential and kinetic energy stays the same. If 100% of one type of energy is input, then 100 % must be output.
30. Law of Conservation of EnergyEnergy Efficiency Energy efficiencycan be thought of as the efficiency with which we are capable of utilizing a resource. If we don't use the energy released from the chemical bonds in a resource, the energy is transformed into heat, sound, thermal vibrations, or light. The heat energy is unusable, and is not lost, but expelled through different parts of the engine and the car’s parts including the tailpipe.
31. The Law of Conservatin of Energy Energy Efficiency The more energy conversion steps there are in a process, the more energy you lose as heat. For example, in order to run a car, the chemical potential energy in the gas (100% potential energy), converts into thermal energy (or heat energy) by igniting the fuel. The thermal energy is converted to mechanical energy to make the engine run. This three step process has an overall maximum efficiency of about 30%. That means that 70% of the energy initially stored in the gasoline was transformed to heat, and 30% was actually converted into mechanical energy—the energy that does the work.
32. The Law of Conservation of Energy Energy Efficiency (cont’d) 100% potential chemical energy went into the engine, and 70% left as heat energy and 30% left as usable work output; so energy came in at 100% and energy left at 100%. The energy came in as chemical potential energy, and left as unusable heat and mechanical energy. No matter what, the amount of energy that goes in is the amount of energy that goes out. You’ll always start at 100% energy and end up with 100% energy, even when the energy has been transformed into several different types of energy.
33. Energy Conservation TOTD