10Kinetic EnergyThe energy of motion is called kinetic energy.
11Kinetic Energy Kinetic energy depends on both mass and velocity. The faster an object moves, the more kinetic energy it has.The greater the mass of a moving object, the more kinetic energy it has.
12Let’s Look…..The vehicles below are traveling at the same velocity of 100 km/h. Do they have the same amount of kinetic energy? Why? Why not?
13AnswerNo, the kinetic energy is different for each vehicle. The truck has a GREATER mass than the motorcycle, so the truck has GREATER kinetic energy.
14Formula for Kinetic Energy K.E. = mass x velocity22K.E. = m X v2What has a greater affect of kinetic energy, mass or velocity? Why?The velocity does because its value is squared!
15Let’s Practice..Calculate the kinetic energy of a 3 kg rock that rolls down the hill with a velocity of 2 m/s.K.E. = m X v22
16Did you get……Calculate the kinetic energy of a 3 kg rock that rolls down the hill with a velocity of 2 m/s.K.E. = 3 X 222K.E. = 6 Joules
17Quiz Time!Show me what you have learned so far by answering the 4 questions that follow….
18Question 1Which has more kinetic energy, a large dog sitting on a sidewalk or a small cat running down the street?The large dogThe small catBoth have the same kinetic energyNeed more information to answer
19Question 2To what property of an object is kinetic energy directly related?VolumeHeightPositionMass
20Question 3Observe the figure below. Which motorcycle has more kinetic energy? Assuming that the motorcycles have the same mass.Motorcycle AMotorcycle BNeed more informationBA
21Question 4Elastic potential energy is measured in ________.Kilograms (kg)Newtons (N)Joules (J)Meters per second (m/s)
23Potential Energy Potential energy is stored energy due to position. Motionless objects havepotential energy!
243 Types of Potential Energy Elastic Potential EnergyChemical Potential EnergyGravitational Potential Energy
25Elastic potential energy- energy stored by something that can stretch or compress
26Chemical potential energy- energy stored in chemical bonds
27Gravitational Potential Energy: energy stored by objects ABOVE Earth’s surface Apple
28Gravitational Potential Energy “The bigger they are the harder they fall” is not just a saying.It’s true!Objects with MORE mass have greater Gravitational potential energy (G.P.E.)
29Gravitational Potential Energy G.P.E. depends on 3 things:1. Mass of the object2. Acceleration due to gravity = 9.8 m/s23. Height of the object
30Formula for G.P.E. G.P.E. = mass X 9.8 m/s2 X height G.P.E = m X 9.8 m/s2 X h
31Let’s Practice..What is the GPE of a 65 kg pole vaulter that is 15 m in the air?G.P.E = m X 9.8 m/s2 X h
32Did you get……What is the GPE of a 65 kg pole vaulter that is 15 m in the air?G.P.E = 65 X 9.8 X 15G.P.E. = 9555 J
33Quiz Time!Show me what you have learned so far by answering the 4 questions that follow….
34Question 1The gravitational potential energy of an object depends on which of the following?Velocity and heightVelocity and weightWeight and heightWeight and acceleration
35Question 2 A B Which vase has more gravitational potential energy? Vase AVase BCan not determineVase A and B have the same GPEAB
36Question 3Green plants store energy from the Sun in what form?Light energyElastic potentialGravitational potential energyChemical potential
37Question 4 Point A Point B Point C Observe the figure on the right. At which point would the roller coaster have the MOST potential energy?Point APoint BPoint CABC
38Conservation of Energy Energy is most noticeable when it changes from one form to another!Think about it…..
39Well, probably not until it fell, right? Would you….Would you think that a book on top of a bookshelf as having much to do with energy?Well, probably not until it fell, right?
40Energy Tranforms…..Energy transforms from one form of energy to another form of energy.Let’s consider……The electrical energy from a light bulb is transformed into what types of energy?Electrical EnergyLight EnergyThermal (Heat) Energy
41Energy Transforms……….. Potential Energy Kinetic Energy Ball slows downBall speeds up
42Kinetic vs. Potential Energy At the point of maximum potential energy, the car has minimum kinetic energy.
44Kinetic-Potential Energy Conversion Roller coasters work because of the energy that is built into the system. Initially, the cars are pulled mechanically up the tallest hill, giving them a great deal of potential energy. From that point, the conversion between potential and kinetic energy powers the cars throughout the entire ride.
45The Law of Conservation of Energy Energy can not be created or destroyed it can only be converted from one form of energy to another.The total amount of energy in the universe remains constant!
46Friction converts some mechanical energy to thermal (heat) energy. Rub your hands together. Feel it!
47Mechanical EnergyMechanical Energy – is the total amount of P.E. and K.E. in a systemM.E. = Total P.E. + Total K.E.
48Nuclear Fission = nuclei split apart (fission=division) Mass is converted to energy in the processes of fission and fusion.Nuclear Fission =nuclei split apart(fission=division)Nuclear Fusion =nuclei combine(fusion FUSE)
49The food calorie (C) is a unit used by nutritionists to measure how much energy you get from various foods.1 calorie = joulesKilocalorie = Calorie
50Quiz Time!Show me what you have learned so far by answering the 4 questions that follow….
51Question 1What energy transformations occur when a lump of clay is dropped?GPE KE thermal energyKE chem PE thermal energyKE GPE thermal energyGPE KE elastic PE
52Question 2Suppose a juggler is juggling oranges. At an orange’s highest point, what form of energy does it have?Mostly potential energyMostly kinetic energyNo potential or kinetic energyEqual amounts of both
53Question 3Which idea is central to the law of conservation of energy?Friction produces thermal energyPeople must conserve energyThe total amount of energy is constantEnergy is the ability to cause change
54Question 4Friction frequently causes some of an object’s mechanical energy to be changed to which of the following forms?Thermal energyNuclear energyGravitational potential energyChemical potential energy