Presentation on theme: "This color = read and write down"— Presentation transcript:
1This color = read and write down Ch. 5: Energizing With EnergyThis color = read and write downAny other color = read and think about
2Every change that occurs, large or small, involves … energy! The Nature of Energy1What is energy?Wherever you are sitting as you read this, changes are taking place—lightbulbs are heating the air around them, the wind might be rustling leaves, rain changing to snow, your body turning food into heat (and the brown stuff)…and on…and on….Every change that occurs, large or small, involves … energy!
3Change Requires Energy The Nature of Energy1Change Requires EnergyEnergy - the ability to cause change OR the ability to do work.Measured in Joules (J)Anything that can cause a change must have energy.Think about all the things you can affect and change in a day’s time (for good and for bad).If you don’t have energy, you don’t feel like doing much of anything soooo… we NEED energy.
4Energy has different forms The Nature of Energy1Energy has different formsElectrical energy– due to the flow of _________.Chemical energy – stored in chemical bonds (ex. food, gas, fuel)Radiant energy – radio waves, light, x-raysThermal energy – heatKinetic energy– movementIs the chemical energy stored in food the same as the energy that comes from the Sun or the energy stored in gasoline?
5Radiant energy from the Sun travels a vast distance through space to Earth 1It warms the planet and is the ultimate source of energy for every living thing on Earth.WHAT AM I ?
6Things that are moving have it. Kinetic Energy – energy of movement measured in Joules (“Jewels”)Things that are moving have it.Things that are sitting still don’t.KE = ½ mv2m is mass (kg)v is velocity (m/s)KE is kinetic energy in Joules (J)
7Sample Problem:As a paralegal your boss (a lawyer) asks youto find the KE of a 1000 kg car that was going20 m/s when it ran a red light and hit someone.Formula: KE = ½ mv2Work: KE = ½ (1000 kg) (20 m/s)2Answer: KE = 200,000 J
8Potential Energy (P.E.)– stored energy. a) Elastic P.E. – from something that can stretch or compress.i.e. – rubber band, spring, shocks, tramp.b) Chemical P.E. – from chemical bondsi.e. – gasoline, food, bombs, natural gasc) Gravitational P.E. – anything that can falli.e. – book on a bookshelf, roller coaster at the top of a hill (formula on next slide)
9GPE = mghGPE is gravitational potential energy (J)m is mass (kg)g is accel. due to gravity (9.8 m/s2)h is height (m)The higher off the ground something is the ______ potential energy it has!
10Sample Problem:As an engineer’s assistant you need to find the GPE of a roller coaster part so you can order the right one. The mass is 1000 kg and it is 10 m off the ground at its highest point.Formula: GPE = mghWork: GPE = (1000 kg)(9.8 m/s2)(10 m)Answer: GPE = (98,000 J)
11Money can be used as an analogy for energy. 1An Energy AnalogyMoney can be used as an analogy for energy.You have a $ 750,000 inheritance coming to you$ 400 is cash$17,500 is gold coins$ 130,000 is CD’s$ 40,000 is in a savings account$ 535,000 is in BASEBALL CARDSWould you want the baseball cards?
12Regardless of its form, money is money. The same is true for energy.Energy from the Sun that warms you...Energy from the food that you eat…Energy from the powerplant that runs your play-station…are only different forms of the same thing.
13Energy can change from one form into another but the total amount NEVER changes. Law of Conservation of Energy – energy CAN NEVER be created or destroyed.
14Kinetic Energy 1 The SI unit of energy is the joule – symbol J. The Nature of Energy1Kinetic EnergyThe SI unit of energy is the joule – symbol J.If you dropped a softball from a height of about 0.5m, it would have a KE of about one joule before it hits the floor.
15Example 3What is the kinetic energy of a baseball moving at a speed of 40 m/s if the baseball has a mass of 0.15 kg?ANS: KE = ½ mv2KE = ½ (0.15 kg)(40 m/s)2KE = 120 J
16GPE: stored energy that is due to an object’s position. The Nature of Energy1GPE: stored energy that is due to an object’s position.If the apple stays in the tree, it will keep the stored energy due to its height above the ground.
17The Nature of Energy1Potential EnergyIf it falls, that stored energy of its position is converted to energy of motion which is ______ ________.
188. Energy Transformations The Nature of Energy18. Energy TransformationsGPE Kinetic and Electricalthe damElectrical RadiantCell phoneElectrical Kinetic (sound wave)mp3 playerChemical Kinetic and Thermal- car taking off
19Starting with the food I ate, diagram the energy transformations as I walk over and turn on the light.T.E.C.P.EK.E.E.E.Starting with the coal from the power plant, diagram the energy transformations on the hair dryerT.E.C.P.E.K.E.E.E.T.E.
20Chemical Potential Energy The Nature of Energy1Chemical Potential EnergyWhen natural gas is burned, energy stored in the bonds that hold the atoms together and is released .
219. Changing GPE 1 GPE changes with height above the ground. The Nature of Energy19. Changing GPEGPE changes with height above the ground.The higher off the ground an object is, themore GPE it has.If two objects are at the same height, the one with the most mass has the most GPE.
22Energy is the ability to cause __________. Q. 1 Section Check1Energy is the ability to cause __________.Q. 1A. changeB. heatC. motionD. work
23Energy is the ability to cause ___change____. Section Check1AnswerThe answer is A.Energy is the ability to cause ___change____.
24List four different forms of energy: Q. 2 Section Check1List four different forms of energy:Q. 2Answerelectrical, chemical, radiant and thermal, (potential & kinetic), GPE
25The kinetic energy of an object depends on __________. Q. 3 Section Check1The kinetic energy of an object depends on __________.Q. 3A. the object’s mass and velocityB. the object’s massC. the object’s velocityD. the acceleration of the object
26Section Check1AnswerThe answer is A. Kinetic energy depends on __the object’s mass and velocity___.
27minor rule changesIf you are sent out to the hall to work on an assignment you must not disrupt other classes.If you do = automatic write-upNo headphones during reading / notes / grading. Only while working on homework and some labs.
28Transforming Electrical Energy Conservation of Energy2Transforming Electrical EnergyLightbulbs transform ________ energy into ______ and _______ energy.
29Transforming Chemical Energy Conservation of Energy2Transforming Chemical EnergyIn a car, a spark plug fires, changing _______ potential energy into __________ energy.
30Transforming Chemical Energy Conservation of Energy2Transforming Chemical EnergyThen, as the hot gases expand, thermal energy is converted into ________ energy.
31Transforming Chemical Energy Conservation of Energy2Transforming Chemical EnergySome energy transformations are less obvious because they do not result in motion, sound, heat,or light.Every green plant converts light energy from the Sun into chemical energy.
32Conversions Between Kinetic and Potential Energy Conservation of Energy2Conversions Between Kinetic and Potential Energy10. Mechanical energy (M.E.) – total amount of potential and kinetic energy in a systemME = PE + KEmechanical energy = potential energy + kinetic energy
342Projectiles: the K.E. and P.E. change, but the M.E of the ball does ___ ________.
35Energy Transformations in a Swing Conservation of Energy2Energy Transformations in a Swing11. Pendulum – how is K.E. effected?more mass = _______ K.E.Shorter string = _____ K.E.Answer this question out loud“how is the energy conserved?”
36Energy Transformations in a Swing Conservation of Energy2Energy Transformations in a SwingAt the ends of the path you have max _____.As it accelerates downward, the P.E. changes over to ______.At the bottom of the path, KE is at its ______.
37Be sure study guide packet is done Read through notes / powerpoints TEST TUESDAYBe sure study guide packet is doneRead through notes / powerpoints12. E.P.E – slingshots, rubber bands, etc.The ______ ball has more G.P.EThe ______ ball has more E.P.E
3813. What law is represented in the diagram? WRITE THE ANSWER The Law of Conservation of Energy213. What law is represented in the diagram? WRITE THE ANSWER
39Is energy always conserved? Conservation of Energy2Is energy always conserved?While coasting along a flat road on a bicycle you will eventually stop if you don’t pedal.A. Write an answer to this question:If energy is conserved, why don’t you keep coasting forever?
40Converting Mass into Energy Conservation of Energy2Converting Mass into Energy14. Nuclear Fusion—takes place in the Sun and other stars.Fusion - a small amount of mass is turned into a huge amount of energy.
41Conservation of Energy 2Nuclear FissionA. The energy before the reaction is equal to the energy after the reaction.
42Conservation of Energy 215. Energy in Your BodySome of the chemical potential energy stored in your body is used to maintain a nearly constant internal temperature.A portion of C.P.E. is converted to heat that your body gives off.
43Energy Conversions in Your Body Conservation of Energy2Energy Conversions in Your BodyYour body stores C.P.E in the form of fat. It gets converted to:- T.E. (heat)K.E. (movement)This C.P.E. is used to fuel the processes that keep you alive (i.e. heart beat, breathing, and thinking).
44Energy Conversions in Your Body Conservation of Energy2Energy Conversions in Your BodyWalking burns the most calories for ______ body frame._____ burns the most calories for all bodies
45Every gram of fat a person consumes can supply 9 C of energy. Conservation of Energy2Food EnergyCalorie (C) — measures food energy (C.P.E.)1 C ≈ 4,184 JCarbohydrates and proteins each supply about 4 C of energy per gram.Every gram of fat a person consumes can supply 9 C of energy.
46Q. 4 Mechanical energy is the total amount of _________ in a system. Section Check2Q. 4 Mechanical energy is the total amount of _________ in a system.A. kinetic energyB. momentumC. potential energyD. potential and kinetic energy
47Section Check2AnswerThe answer is D. Mechanical energy is the energy due to position and motion of all objects in a system.
48Q.5 Define the law of conservation of energy. Section Check2Q.5 Define the law of conservation of energy.AnswerThe law of conservation of energy states that energy cannot be created or destroyed. It can only change forms.
49Q.6 Friction converts ________ energy into _________ energy. Section Check2Q.6 Friction converts ________ energy into _________ energy.A. electrical, thermalB. mechanical, thermalC. thermal, electricalD. thermal, mechanical
50Section Check2AnswerThe answer is B. Friction converts mechanical energy into thermal energy.
51Q. 7 KE = ½ mv2Write what happens to the energy if the mass is doubled?Write what happens to the energy if the velocity is doubled? Why is this?Answer: If m is doubled, KE is doubled If v is doubled, KE is quadrupled, because it is squared.
52Einstein’s famous formula Reviewing Main Ideas2Einstein’s famous formulaE = mc2- E is energy, m is mass, and c is the speed of light.- States that mass is energy.- A tiny bit of mass gets converted to a huge amount of energy because the speed of light is a huge number.
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