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Energy!!!

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  • 1. Energy!!!Energy!!!
  • 2. The Law of Conservation ofThe Law of Conservation of EnergyEnergy Energy cannot be created orEnergy cannot be created or destroyed; it may be transformeddestroyed; it may be transformed from one form into another, but thefrom one form into another, but the total amount of energy nevertotal amount of energy never changes.changes.
  • 3. ““the ability to do work”the ability to do work” The combination of energy andThe combination of energy and matter make up the universe:matter make up the universe: – Matter is substance, and energy isMatter is substance, and energy is the mover of substance.the mover of substance. What is energy?What is energy?
  • 4. Energy isEnergy is nature’s way of keeping score.nature’s way of keeping score. We sense energyWe sense energy only when theonly when the score changes,score changes, either aeither a transformationtransformation from one form offrom one form of energy to another,energy to another, or a transfer ofor a transfer of energy from oneenergy from one point to another.point to another.
  • 5. How is all energy divided?How is all energy divided? Potential Energy Kinetic Energy All Energy Gravitation Potential Energy Elastic Potential Energy Chemical Potential Energy
  • 6. Potential KineticPotential Kinetic energy ofenergy of position orposition or energy inenergy in storage.storage. – Water behind aWater behind a damdam – Hammer over headHammer over head – Food on the plateFood on the plate energy ofenergy of motion, the formmotion, the form capable of doingcapable of doing workwork – Flowing waterFlowing water – A falling hammerA falling hammer – ElectronsElectrons regenerating ATP inregenerating ATP in a bio’l cella bio’l cell
  • 7. PE = mghPE = mgh m = massm = mass (kg)(kg) h = heighth = height (m)(m) g = accel dueg = accel due to gravityto gravity –(9.8 m/s(9.8 m/s22 ))
  • 8. What is Gravitational PotentialWhat is Gravitational Potential Energy?Energy? o Potential energyPotential energy due to an object’sdue to an object’s positionposition o P.E. = mass xP.E. = mass x height x gravityheight x gravity Don’t look down, Rover! Good boy!
  • 9. What is Potential Energy?What is Potential Energy? o Energy that is storedEnergy that is stored and waiting to beand waiting to be used laterused later
  • 10. What is Elastic Potential Energy?What is Elastic Potential Energy? o Potential energy due compression orPotential energy due compression or expansion of an elastic object.expansion of an elastic object. Notice the ball compressing and expanding
  • 11. What is Chemical Potential Energy?What is Chemical Potential Energy? o Potential energyPotential energy stored within thestored within the chemical bonds ofchemical bonds of an objectan object
  • 12. What is Kinetic Energy?What is Kinetic Energy? o Energy an object has dueEnergy an object has due to its motionto its motion o K.E. = .5(mass x speedK.E. = .5(mass x speed22 ))
  • 13. KE = 1/2 m vKE = 1/2 m v22 4 kg bowling4 kg bowling ballball at 10 m/sat 10 m/s = .5 (4kg)= .5 (4kg) (10m/s)(10m/s)22 = 200 J= 200 J .25 kg baseball.25 kg baseball at 50 m/sat 50 m/s = .5 (.25kg) (50= .5 (.25kg) (50 m/s)m/s)22 = 312 J= 312 J
  • 14. Courtesy Jerry Ohlinger’s Movie Material Store Work is done when a force is exerted over a distance.
  • 15. WorkWork is equal to the force that is exertedis equal to the force that is exerted times the distance over which it istimes the distance over which it is exerted.exerted. W = F x dW = F x d The unit of work combines theThe unit of work combines the unit of force (N) with the unit ofunit of force (N) with the unit of distance (m)distance (m) Newton-meter (N-m) aka Joule.Newton-meter (N-m) aka Joule.
  • 16. You carry aYou carry a 20 kg suitcase20 kg suitcase upstairs, aupstairs, a distance of 4mdistance of 4m. How much work did you. How much work did you do?do? W = F x dW = F x d F = maF = ma = (20 kg) (10m/s= (20 kg) (10m/s22 ) = 200 N) = 200 N W = F x dW = F x d = (200 N) (4m)= (200 N) (4m) = 800 J= 800 J
  • 17. PowerPower measures the rate of work done.measures the rate of work done. or the rate at which energy isor the rate at which energy is expended.expended. Power is the amount of workPower is the amount of work done, divided by the time it takesdone, divided by the time it takes to do it.to do it. Power (watts) = work (joules) /Power (watts) = work (joules) / time (sec)time (sec) P = W/tP = W/t
  • 18. PowerPower Since work performed equals energySince work performed equals energy expended,expended, Power (watts) = energyPower (watts) = energy (joules) / time (sec)(joules) / time (sec) The watt is defined as theThe watt is defined as the expenditure ofexpenditure of 1 joule of energy in 1 second.1 joule of energy in 1 second. (75 watt light bulb consumes 75(75 watt light bulb consumes 75 J/sec)J/sec)
  • 19. Important formulas and unitsImportant formulas and units QuantityQuantity DefinitionDefinition UnitsUnits ForceForce mass x accel.mass x accel. newtonsnewtons WorkWork force x distanceforce x distance joulesjoules EnergyEnergy power x timepower x time joulesjoules PowerPower work / timework / time wattswatts
  • 20. Ex. Problem on Power:Ex. Problem on Power: Your CD system, uses 250 watts ofYour CD system, uses 250 watts of electrical power.electrical power. You play it for 3 hrs. How muchYou play it for 3 hrs. How much energy used? About how much wouldenergy used? About how much would it cost?it cost? If one kWh is $.08.If one kWh is $.08. Energy (J) = power (watts) x timeEnergy (J) = power (watts) x time (sec) = (250w) (3hr) = 750 Whr = .(sec) = (250w) (3hr) = 750 Whr = . 75 kWh75 kWh The cost = 8 cents/ kWh x .75 kWhThe cost = 8 cents/ kWh x .75 kWh = 6 cents= 6 cents
  • 21. 6 fundamental forms of energy6 fundamental forms of energy 1.1. mechanical energymechanical energy 2.2. Thermal (heat) energyThermal (heat) energy 3.3. electromagnetic energyelectromagnetic energy 4.4. electrical energyelectrical energy 5.5. nuclear energynuclear energy 6.6. chemical energychemical energy
  • 22. What is the source of ourWhat is the source of our energy?energy? The source ofThe source of practically allpractically all our energy isour energy is the Sunthe Sun..
  • 23. What is Mechanical Energy?What is Mechanical Energy? o Energy due to anEnergy due to an object’s motionobject’s motion (kinetic) or position(kinetic) or position (potential).(potential). The bowling ball hasThe bowling ball has mechanical energy.mechanical energy. When the ball strikesWhen the ball strikes the pins, mechanicalthe pins, mechanical energy is transferredenergy is transferred to the pins!to the pins!
  • 24. Examples of Mechanical EnergyExamples of Mechanical Energy
  • 25. What is ElectromagneticWhat is Electromagnetic Energy?Energy? o Light energyLight energy o Includes energy fromIncludes energy from gamma rays, xrays,gamma rays, xrays, ultraviolet rays,ultraviolet rays, visible light, infraredvisible light, infrared rays, microwave andrays, microwave and radio bandsradio bands
  • 26. What is Electrical Energy?What is Electrical Energy? o Energy caused byEnergy caused by the movement ofthe movement of electronselectrons o Easily transportedEasily transported through power linesthrough power lines and converted intoand converted into other forms ofother forms of energyenergy
  • 27. What is Chemical Energy?What is Chemical Energy? o Energy that isEnergy that is available for releaseavailable for release from chemicalfrom chemical reactions.reactions. The chemical bonds inThe chemical bonds in a matchstick storea matchstick store energy that isenergy that is transformed intotransformed into thermal energy whenthermal energy when the match is struckthe match is struck..
  • 28. Examples of Chemical EnergyExamples of Chemical Energy
  • 29. What is Thermal Energy?What is Thermal Energy? o Heat energyHeat energy o The heat energy of anThe heat energy of an object determines howobject determines how active its atoms are.active its atoms are. A hot object is one whose atomsA hot object is one whose atoms and molecules are excitedand molecules are excited and show rapid movement.and show rapid movement. A cooler object's molecules andA cooler object's molecules and atoms will show lessatoms will show less movementmovement..
  • 30. QUIZ TIME!QUIZ TIME! What type of energyWhat type of energy cooks food in acooks food in a microwave oven?microwave oven? ELECTROMAGNETICELECTROMAGNETIC ENERGYENERGY What type of energy isWhat type of energy is the spinning platethe spinning plate inside of a microwaveinside of a microwave oven?oven? MECHANICAL ENERGY
  • 31. QUIZ TIME!QUIZ TIME! Electrical energy isElectrical energy is transported to your housetransported to your house through power lines.through power lines. When you plug an electric fanWhen you plug an electric fan to a power outlet, electricalto a power outlet, electrical energy is transform intoenergy is transform into what type of energy?what type of energy? MECHANICAL ENERGYMECHANICAL ENERGY
  • 32. QUIZ TIME!QUIZ TIME! What energy transformationWhat energy transformation occurs when an electric lampoccurs when an electric lamp is turned on?is turned on? ELECTRICAL ENERGYELECTRICAL ENERGY ↓↓ ELECTROMAGNETIC ENERGYELECTROMAGNETIC ENERGY
  • 33. What types of energy are shown below?What types of energy are shown below? Mechanical and Thermal EnergyMechanical and Thermal Energy ((Don’t forget frictionDon’t forget friction))
  • 34. What type of energy is shown below?What type of energy is shown below? Chemical EnergyChemical Energy
  • 35. What types of energy are shown below?What types of energy are shown below? Electrical, Mechanical andElectrical, Mechanical and Electromagnetic EnergyElectromagnetic Energy
  • 36. What type of energy is shown below?What type of energy is shown below? Chemical Energy (yummy)Chemical Energy (yummy)
  • 37. What type of energy is shown below?What type of energy is shown below? Thermal EnergyThermal Energy
  • 38. What types of energy are shown below?What types of energy are shown below? Mechanical, Electromagnetic,Mechanical, Electromagnetic, Electrical, Chemical and ThermalElectrical, Chemical and Thermal EnergyEnergy
  • 39. The Law of Conservation ofThe Law of Conservation of EnergyEnergy Energy cannot be created orEnergy cannot be created or destroyed; it may be transformeddestroyed; it may be transformed from one form into another, but thefrom one form into another, but the total amount of energy nevertotal amount of energy never changes.changes.