Presentation on theme: "Interesting observation….. Describe what happens when an alcohol thermometer is placed in warm water. “the heat from warm water is transferred to the alcohol”"— Presentation transcript:
Interesting observation….. Describe what happens when an alcohol thermometer is placed in warm water. “the heat from warm water is transferred to the alcohol” “energy is transferred into the system (thermometer)” “temperature is transferred to alcohol” “the warmth is transferred from water to thermometer” “energy in warm water is transferred to alcohol particles” “energy in warm water changes energy in alcohol” “water particles hit thermometer and lose their energy which causes alcohol molecules to speed up” Why does it seem like many of us UNDERSTAND the general concept, but when asked to explain it…..it seems like several different languages are being spoken
Heat=energy=warmth=speed???? Though all related…..they do not all mean the same thing -Problematic because we use such words interchangeably all the time in discussion Our general goal in this unit is really to focus on energy and its role at the atomic level -What is it? -Are there different kinds? -Can it change form? -Is it something we can see? -How can we calculate it? -Where does it go?!?!
Substance Metaphor Focuses attention on energy storage and transfer “substance-like” entity present in every system Information analogy….. My computer, my flash drive, LCWM computer, LCWM printer, your brain! -We would never say that the information that was originally on my computer was somehow transformed into flash drive info or LCWM computer info…… -Instead, we clearly understand that the information must have simply been transferred somehow and stored in each device -Energy works the same way! -Stored in different systems in different ways and is transferred from one system to another by some mechanism
Energy is transferred in several different ways between system and surroundings Heating (Q)- transfer of energy through collision of particles Working (W)- transfer of energy when macroscopic objects exerts forces on each other Radiating (R)- transfer of energy by the emission or absorption of light The only form of energy that we have worked with so far is thermal energy (E th ) This expression of energy involves the motion of particles and the mass of the system
Which method is energy being transferred? heating radiating working
Water Demo Quick WB session 1.) represent particles of both beakers before I added warm/hot water 2.) represent particles of both beakers after I added warm & hot water -describe how motion of particles changed and how it changed (what caused this change in motion?) -involve the term “energy” in your descriptions -which beaker had more thermal energy (E th ) at the end and why?
Heat vs. Temperature Temperature: Depends solely on the speed of the particles Measure of “how fast” particles are moving in a system Heat: Depends on both speed and mass of the system Heating (Q): one of several energy-transfer mechanisms. Transfers energy via collision of particles
Addition of energy to solids/liquids What happens when we add energy to solids? - attractive forces between particles begin to weaken -Particles begin to “shake” more and more trying to break free