Section 10.1 Energy, Temperature, and Heat 1.To understand the general properties of energy 2.To understand the concepts of temperature and heat 3.To understand the direction of energy flow as heat Learning Objectives

Section 10.1 Energy, Temperature, and Heat What do we know about energy? It’s not matter / made of atoms It is needed for motion It is needed for life We get it from the chemical bonds in food molecules Matter contains energy  atoms & molecules, chemical bonds It comes in many forms: heat, light, motion It can move from one place to another and change from one form to another Modern societies use energy from fossil fuels, nuclear processes, wind power, solar power, chemical reactions – these can all be used to make electricity

Section 10.1 Energy, Temperature, and Heat Energy is the ability to do work or produce heat. Potential energy Energy of position Kinetic energy Energy of motion A. The Nature of Energy (pictures not in notes)

Section 10.1 Energy, Temperature, and Heat A. The Nature of Energy Law of conservation of energy –Energy can be converted from one form to another but can neither be created nor destroyed.

Section 10.1 Energy, Temperature, and Heat WATER HEIGHT  POTENTIAL ENERGY WATER MOVES  KINETIC ENERGY

Section 10.1 Energy, Temperature, and Heat KINETIC ENERGY IN WIND CAN BE CONVERTED INTO ELECTRICAL ENERGY FLOWING ON A WIRE

Can you tell kinetic energy from potential energy? Disclaimer: The video clip you are about to watch shows kids engaging in a dangerous activity (free running) that is likely to result in bodily injury; I do NOT recommend this. It does provide us with a beautiful illustration of kinetic and potential energy!

Section 10.1 Energy, Temperature, and Heat How does heat energy flow?

Section 10.1 Energy, Temperature, and Heat Biology Flashback Mammals are homeothermic – they keep a constant body temperature even though the environmental temperature changes. Why must we use energy to keep our bodies warm? Heat flows from where there is more to where there is less…

Section 10.1 Energy, Temperature, and Heat Temperature is a measure of the random motions of the components of a substance. B. Temperature and Heat (pictures not in notes) Hot waterCold water (90. o C) (10. o C)

Section 10.1 Energy, Temperature, and Heat Heat is a flow of energy between two objects due to a temperature difference between the objects. –Heat is the way in which thermal energy is transferred from a hot object to a colder object –If a temperature gradient exists, heat will flow (if it can) until the system reaches equilibrium (same temperature all over) B. Temperature and Heat Hot water Cold water (90. o C) (10. o C) Water Water (50. o C) (50. o C)

Section 10.1 Energy, Temperature, and Heat C. Exothermic and Endothermic Processes (not in notes) System – part of the universe on which we focus attention Surroundings – everything else in the universe Burning a match

Section 10.1 Energy, Temperature, and Heat C. Exothermic and Endothermic Processes (picture not in notes) Exothermic – energy flows out of the system Endothermic – energy flows into the system

Section 10.1 Energy, Temperature, and Heat Ex.: Metabolic Reactions Can be exothermic or endothermic –Exothermic reactions produce heat to maintain body temperature –Endothermic reactions require energy to occur: Break down food  release energy (exergonic) Thinking, moving, building proteins, etc.  absorb energy (endergonic)

Section 10.1 Energy, Temperature, and Heat C. Exothermic and Endothermic Processes (notes summary) Exothermic – energy flows out of the system Endothermic – energy flows into the system A+B AB A+B AB