Bellringer: When do you use energy? Do you know any forms of energy? STOTD

Things to know... Concept Symbol Units Kinetic Energy KE Joules (J) Potential Energy PE Heat Q Height h Meters (m) Specific Heat c J/g•°C or J/g•K Temperature T °C or K

Energy and Energy Transfer Chapter 15 and 16

Energy Energy The ability to do work Measured in Joules (J) Work = Transfer of Energy end

Energy Kinetic Energy (KE) The energy of motion end

Energy An arrow with a mass of 0.07 kg flies through the air at 28 m/s. What is the kinetic energy of the arrow? If a 200 kg log rolling down a mountain has 50000 J of kinetic energy, how fast is the log moving? end

Energy Potential Energy (PE) Stored Energy Many types, but we use Gravitational Potential Energy Remember Fg = mg Fg = weight! end

Energy A rock with a mass of 45 kg is held 2 m above the ground. What is the rock’s potential energy? A man weighing 420 N jumps off a table that is 1.5 m high. What was his potential energy as he jumped off the table? end

Types of PE Energy Electrical Elastic Gravitational Chemical Nuclear Stored in an object's height Chemical Stored in chemical bonds Electrical Electric charges Elastic Stretching or compressing (a spring or a rubber band) Nuclear Stored in the nucleus of an atom end

Energy The Law of Conservation of Energy Energy cannot be created or destroyed, it can only be converted into another form 50 J 50 J 0 J 100 J end

Energy 3 1 2 Point 3: Start: Point 1: Point 2: Ball is moving slower, KE = 196 J Ball has gained height, PE = 980 J Some KE  PE Start: Ball at rest, KE = 0 Ball has height, PE = 1176 J Point 1: Ball is moving, KE = 588 J Ball has lost height, PE = 588 J Some PE  KE 3 Point 2: Ball is moving faster, KE = 1176 J Ball has lost ALL height, PE = 0 J All PE  KE 1 2 end

Thermal Energy Heat Thermal Expansion Transfer of thermal energy Moves from Hot Objects to Cold Objects Temperature: the measure of how much thermal energy is in an object. Thermal Expansion When an object is heated, it expands (gets bigger) In the winter, rings are lose on your fingers end

Bellringer: What is Heat? What are the units of measurement for heat? A 5.0 kg flower pot is sitting on a ledge 3 m above the ground. What is the flower pot’s potential energy? What is it’s kinetic energy? STOTD **You will need a Calculator today!

Thermal Energy Specific Heat (c) Heat needed to raise the temp. of a substance Low Specific Heat = Less Energy Needed Units: J/g∙°C end

Thermal Energy Heat (Q) Measured in joules (J) or calories (cal) 1 Calorie (big C from food labels) = 1000 cal end

Thermal Energy A piece of iron has a mass of 500 g. If iron has a specific heat of 0.449 J/g·°C, how much heat must be absorbed to raise the temperature by 95 °C. 100 g of water at 25 °C is placed in a cup. The cup is heated so the water is now at 60 °C. Specific heat of water is 4.18 J/g·°C. How much heat was absorbed by the water? end

Back to the Law of Conservation of Energy… Have you ever ridden a rollercoaster? https://youtu.be/J8pJiV44hVM https://youtu.be/LrRdKmjhOgw

Thermal Energy Calorimeter Measure changes in thermal energy Uses the principle that heat flows from hot to cold Calculates the energy of a substance by blowing it up to heat water end

Bellringer: A man weighing 40 N jumps off a table that is 1.5 m high. What was his potential energy as he jumped off the table? A piece of iron has a mass of 0.509 g. If iron has a specific heat of 0.449 J/g·°C, how much heat must be absorbed to raise the temperature by 15 °C. STOTD

Energy Transfer Conduction Transfer of thermal energy by objects touching Touch Hot Stove = Energy goes into your Hand Conductor Allows thermal energy to flow Metal, Tile Insulators Does not allow thermal energy to flow Wood, Styrofoam end

Energy Transfer Convection Transfer of thermal energy by particles moving around Heat/AC is circulated through your house Important in natural cycles (oceans, weather, magma) end

Energy Transfer Radiation Transfer of thermal energy by waves moving through space All objects radiate heat As an object gets hotter it gives off energy faster end

Energy Transfer: Thermodynamics Study of thermal energy changing to other types 3 laws of Thermodynamics 1st Law of Thermodynamics Energy is conserved Energy will change forms, but the total energy is always the same 2nd Law of Thermodynamics Energy can flow from cold to hot objects, only by doing work 3rd Law of Thermodynamics Absolute zero cannot be reached end

An arrow with a mass of 0. 7 kg flies through the air at 21. 5 m/s An arrow with a mass of 0.7 kg flies through the air at 21.5 m/s. What is the kinetic energy of the arrow? If a 20 kg log rolling down a mountain has 540 J of kinetic energy, how fast is the log moving? A rock with a mass of 4.5 kg is held 32 m above the ground. What is the rock’s potential energy? A man weighing 40 N jumps off a table that is 1.5 m high. What was his potential energy as he jumped off the table? A piece of iron has a mass of 0.509 g. If iron has a specific heat of 0.449 J/g·°C, how much heat must be absorbed to raise the temperature by 15 °C.

Bellringer: A piece of iron has a mass of 0.509 g. If iron has a specific heat of 0.449 J/g·°C, how much heat must be absorbed to raise the temperature by 15 °C. STOTD

Bellringer: How can energy be transferred from one object to another? (we mentioned three ways yesterday). How does a roller coaster transfer energy? STOTD