Download to read offline
More Related Content
Energy
- 1.
- 2. Energy • Energy isthe ability to do work You can think of the meaning of work in physics as the ability of a force to move something.
- 3. Forms of energy •Electrical energy • Heat energy • Light energy • Solar energy – sun (heat + light) • Sound energy (vibration) • Potential energy • Kinetic energy - movement
- 4. Basic question youneed to know How do you identify the different forms of energy?
- 5. Heat energy Its HOT! Bytemperature
- 6. Also recall: Heat willalways travel from hotter(warmer) place to a colder place i.e. of there is a difference in temperature, heat transfer will occur until all the things in the surrounding are the same temperature
- 7. Sound energy Vibration Your earspick it up as sound or music
- 8. Heat and soundenergy can only be passed through a medium (matter) e.g. sound cannot pass through outer space
- 9. Electrical energy All thehigh tech and machine stuff use this energy – they have metal parts
- 10.
- 11. Solar energy from theSUN Solar energy contains special light that - Heats up earth - UV light :: sunblock, photosynthesis - Visible light (bright)
- 12. Kinetic energy Anything thatmoves has kinetic energy!
- 13. Law of conservationof energy. Energy is never created or destroyed, just converted from one form to another.
- 14. And that featureof energy is useful! Why?
- 15. Examples of wantedenergy conversion Electricity heat (microwave) or sound (loud speaker) or light (lamp, tv screen) Fuels into heat (cooking with gas) or kinetic energy (petroleum and car) Electrical generator: CPEHEKEEE
- 16. Examples of unwantedenergy conversion: Kinetic energy lost as heat (friction) or sound That is the reason why we need to pump petrol Without friction, the car will move forever with just a push
- 17. Examples of energyconversion: Solar energy chemical potential energy :: photosynthesis Essential for all life on earth!
- 18. Energy sources • Thesun. • Living things depend directly or indirectly on the sun for energy. • Fuels and food are potential energy
- 19. • Living thingsrequire energy - respiration • Non living things can also have energy • Plants use the energy of the sun (solar energy, which contains light energy) and converts it into food (chemical potential energy)
- 20. Solar energy • energyfrom the sun • Source of energy on earth • Solar energy is often experienced as heat and light energy • Used for photosynthesis to make food
- 21. Did you know?– advanced science • How does the sun produce energy seemingly from nowhere? • Remember the law of energy: energy cannot be created nor destroyed, only converted from one form to another.
- 22. • It turnsout, you can release energy from mass
- 23. • The sunis basically a giant ball of hydrogen atoms • On the sun, it is hot enough to start nuclear fusion • A process where smash two atoms together to make a larger atom, • which releases energy. • it is clean energy as the product is helium gas
- 24. This huge amountof heat and light is solar energy It travels through space and reaches earth
- 25. The sun isthe indirect primary source of energy on earth Plants use sunlight to photosynthesis Plants are the primary source of the food chain Trees that died millions of years ago provide us with fuel for cars, cooking and electricity
- 26. What happens ifthere is no sun? Remember the asteroid that hit earth millions of years ago causing dinosaurs to become extinct? Besides the impact of the collision killing animals It caused clouds of dust to rise in the air, blocking out sunlight Killed plants and led to mass extinction – animals starved to death
- 27. Which is equivalentto this
- 28. What is potentialenergy? Stored energy What are the forms of PE?
- 29. Potential energy -CPE • Chemical potential energy - CPE • E.g. of CPE fuels (petrol), food, batteries
- 30. Chemical potential energy •potential energy that is stored in chemical bonds. • Energy is released when bonds between atoms are broken or formed.
- 31. • Photosynthesis -Plantsconvert light (solar) energy into CPE (food) • In respiration, cells convert food (CPE) into energy
- 32. • Batteries (CPE)are used to power devices (EE) • Fuel, petrol (CPE) is burnt to provide energy eg to move a car (EE, KE) • Food is burnt during respiration to provide living things energy
- 33. Remember! Battery = CPE:: CPE EE bulb light up Petrol = CPE :: CPE EE KE car moves Food = CPE :: CPE heat E (keep you warm) or KE (move your muscles) Or various chemical processes; living things basically a lot of chemical reactions inside
- 34. Different types ofpotential energy -gravitational PE -chemical PE -elastic PE GPE CPE EPE remember remember!!
- 35. Potential energy (cont) •Gravitational potential energy • (height) e.g. hydroelectric power • Elastic potential energy e.g. stretch string
- 36. What is gravitationalpotential energy? • Anything at a high position has gravitational potential energy • It doesn’t refer to the height of the object but the height of the object’s position • Means you are at a high up place, but not you are tall
- 37. • GPE resultingfrom earth exerting its gravity on the object • Gravity is dependent not only on height(position), but also the mass of the object • Height: if you jump down from a higher place, ↑ GPE • Mass: If you are heavier and you jump down, ↑ GPE
- 38. What has GPE? •sliding down a slide GPE KE • falling down a height GPE KE • hydroelectric power plant GPE KE EE
- 39. Elastic potential energy •comes from stretched rubber band, wound up toy, stretched spring • The stretched elastic wants to return to its original relaxed state • The potential energy PE is stored as stretched/wound up state
- 40. Examples of EPE •Wound up toy • Trampoline • Spring balance – it wants to go back to its original shape • Stretched rubber band - same
- 41. Trampoline: EPE KE GPE (repeat again) Wound up toy : EPE > KE
- 42. Recall again: Law ofconservation of energy. Energy is never created or destroyed, just converted from one form to another.
- 43. • Examples ofenergy conversion: • Pendulum: gravitational potential energy to kinetic energy
- 44. Kinetic energy = anythingthat moves has kinetic energy KE
- 45. Examples of energyconversion involving KE and GPE • GPE KE and KE back GE within the same system • E.g. throwing a ball into the air • Swinging pendulum
- 46. Conservation of energy Totalenergy is conserved Maximum height Maximum speed two examples where KE and PE Inter convert are swinging pendulum And ball tossed into the air Swinging pendulum Ball tossed into the air
- 47. So if youtoss the ball higher, it will fall back down with a faster speed If you swing the pendulum from a greater height, it will swing faster
- 48. Fun to know Newton’scradle – an example of conservation of energy GPE KE
- 49. Kinetic energy • KEoften depleted by friction • Friction opposes motion = KE • KE converted by friction heat and sound • Eg car moving car motion is opposed by friction • Without friction, you will never have to use petrol to fuel your car! :: petrol = CPE = ↑ energy to the car engine
- 50.
- 51. • The oppositeof fusion is nuclear fission • where you split an atom into two atoms. • This also releases energy • but generates radioactive atoms (unstable) atoms • radioactive atoms have energy that can cause mutation • Remember the nuclear bombs that hit Japan during WWII
- 52. Besides bombs, thisscience can be used for nuclear energy The amount of energy released during nuclear fission is huge – enough for power homes for a year. It would be nice to have so much energy However, the downside is the radioactive waste produced Exposure to radioactivity causes mutation and cancer
- 53. What’s the bigdeal about energy We are running out of energy sources We are polluting the earth when we burn traditional fuels for energy We are causing damage to the land when we extract energy sources from the earth
- 54.
- 55.
- 56.
- 57.