4What is heat? In your journal – tell me what heat is, can you hold it? How do you “get” it? How do you “acquire” heat?What’s happening on the molecular level when there is “heat”?How does heat get from one thing to another thing?
5Journal QuestionsWhen we check a weather report to find out the temperature, what are we finding the temperature of?When do you think it is hottest during the day? Why?When is the coldest? Why?Where in our local environment might it be the very hottest during the hot part of our day/Do you think the surface of Earth affects how hot the air gets?
6What happens to different earth materials when the sun shines on them? What is an earth material?What is the main source of energy that could heat these earth materials?
7Investigation Time Experimenting! Lab Sheet Materials Data Table Why do we want the thermometer bulb below the surface of the sand, soil, and water?Data Table
8ProceduresRead the temperature of the material in each container before going out.Record the temperatures in the columns of the data chart every 3 minutes.Find a place in the “sun” and place a newspaper that has been folded 3x on the ground and the earth materials on top of the newspaper – (why do we need to put them on newspaper?)Continue to monitor and record the temperature of each earth material every 3 minutes for 15 minutes
9Procedures Cont.After 15 minutes, move the four containers to a non-sun spot. Record temperatures every 3 minutes for 15 minutes.
10Back in the Classroom Return all materials Complete data sheet Analyze the dataGraph sheetCalculate the temperature changes for each earth materialUse colored pencils for each different materialLabel the x-axisLabel the y-axis
11Earth Material Questions Answer these questions in your journal. Be sure to include the question in your answer.Which material heated up the most in 15 minutes? Why?Which material heated up the least in 15 minutes? Why?Which material cooled off the fastest? Why?Which material cooled off the least? Why?Did all four earth materials receive the same amount of solar energy? Support your answer with dataWhich properties of the earth materials do you think may have caused the temperature differences? Why?
12Water is SpecialIf each earth material received the same amount of solar energy, how can you explain the differences in temperature?Water has an important property. It takes 5x the heat energy to raise an amount of water one degree than it takes to raise the temperature of an equal amount of dry soil or sand one degree. When the same amount of heat energy is absorbed equally be all materials, the temperature of the solid earth materials goes up faster than water.
13Water is Special cont.If a kilogram of water and a kilogram of soil absorb equal amounts of solar energy, the temperature of the soil will be much higher that the temperature of the water. The water doesn’t get as hot, but it has absorbed the same amount of heat energy.water soil5 C1 C
14Consider the following… water soilWhy is this a good thing for our earth?How does this relate to global warming and our earth?1 C5 C
15Energy What kind of energy heated up the earth materials? How did the energy get from the sun to the materials?Energy comes from the sun as radiant energy. Radiant energy travels as waves through space and through air. Radiation from the sun can be visible like ________, or invisible like _________, ___________, __________, ________, ________ and other wavelengths.
16Radiation on the Molecular Level When radiant energy strikes an atom or molecule, like a water molecule or a molecule in sand, soil, or air, the molecule gains energy and begins to move faster or vibrate more. We say the molecule absorbed the radiant energy. Absorbing radiant energy is one way energy transfers to matter.Molecular motion is heat. The more motion there is in the molecules of matter,the hotter it is.That’s Hot!
17Let the Sun Shine!Radiation is one way energy can travel over great distances or short distances. When you stand in the sunshine, you are receiving energy from 150 million kilometers away. When you reach out to warm your hands at a campfire, radiant energy given off by the blaze a meter or two away is absorbed by molecules in your skin, and your hands warm up.
18Even through space…Radiant energy travels through the vacuum of space, and some wavelengths travel through air and other transparent materials, like glass, plastic, and water. Radiant energy is energy transfer at a distance without direct contact b/t the energy source and the energy receiver.
19Differential HeatingDifferent materials heat up at different rates. This is called differential heating. Differential heating accounts for the difference in the temperature of water and soil after they have both been in the sunshine for the same length of time. Water in oceans and lakes can store more heat than can landmasses, even though the temperature of the water may be lower.
20Investigation 4/Part 1 Wrap-up Heat and Energy AnimationRead “Thermometer: A Device to Measure Temperature.” on pg and complete the thermometer worksheet.
22Conduction Let’s review: What is radiation? How does radiation affect the surface of Earth?
23Radiation Remembers Radiation is energy that passes through space. Earth receives radiation from the sun.Radiation comes in different wavelengthsVisible lightInfraredUltravioletmicrowave,X-RayRadioRadiation is transferred w/o direct contact.
24Visible LightVisible light is the main kind of energy from the sun that heats Earth. Energy is transferred when light energy is absorbed by molecules in Earth’s surface, causing them to move faster, which increases temperature.
25Consider the following… Think about an 85 degree sunny day – you’re walking barefoot on a sidewalk…What did you feel?Why did your feet feel hot?How did heat transfer from the cement to your feet?
26Your ChallengeYou have some water that is about 30 degrees Celsius – too cold.I thought I would warm it up by mixing it with some of this hot water, but this hot water has salt and red coloring in it. I don’t want any salt or red in my cold blue water.And these are the only materials.How can you warm up the blue water with only these materials?
27The RulesEach group can have two cups, two vials, and four thermometers.When you have decided on the procedure you will use, obtain some red hot water and some blue cold water.Keep records of your procedure and data as your experiment progresses using your lab sheet.
28Your QuestionHow can you warm the cold blue water without mixing it with the hot red water?You can only use the following materials for warming purposes…Cold waterHot waterPlastic cupsFoam cupsVialsthermometers
29Didja do it?Was your group able to raise the temperature of the cold water?How were you able to do this?How did heat transfer from the hot water to the cold water?
30Conduction ExplainedFirst of all, there was no cold, only heat. What we perceive as cold is actually low levels of heat. When you hold an ice cube in your hand, cold doesn’t go into your hand, energy goes out of your hand into the ice cube.Heat is the motion of atoms and molecules. The greater the motion, the more heat energy there is a solid, liquid, or gas.
31ContinuedWhen material 1, with lots of heat or molecular motion, comes in contact with material 2, which has less molecular motion, the energized molecules in material 1 bang into molecules in material 2 and get them moving faster. As a result, molecules in material 2 is now hotter. Molecules in material 1 have less motion (heat) so material 1 is now cooler.
32ConductionEnergy transfer happens between molecules or atoms when they come in contact.What is called when heat is transferred w/o contact?This kind of heat transfer is conduction. Heat can transfer by conduction from atom to atom in a material, or b/t 2 different materials when their atoms or molecules make contact.Multimedia time - Conduction
33Energy DiagramAnalyze the energy experiment you completed by drawing an energy diagram, starting with hot water to the alcohol in the thermometer.Does your diagram look like this?Hot waterPlastic vialCold waterGlass of thermomAlcohol in therm
34Journal Questions Write a definition for heat. Describe heat conduction.Explain your understanding of how heat transfers from one material to another.Explain why a pop can feel cold when you take it out of the refrigerator.Draw an energy diagram of the pop from refrigerator to your hand.
36Consider the following… Did you ever reach for a metal spoon that was in a pot of cooking soup? If so, you might have been surprised to find that it was really hot. But the spoon handle was not in the soup.How did the handle of the spoon get so hot?Let’s investigate…
37Conduction Investigation Question: Does heat energy transfer through solids?Materials:Aluminum and steel barsTemperature stripsThermometersFoam cupsLarge plastic cupstape
38Temperature StripsThis is a liquid-crystal temperature strip. The crystals sealed inside turn color when they reach a certain temperature. Different crystals produce their color at different temperatures.Some crystal colors turn on when the temperature reaches a certain level, and turn off when the temperature goes higher than that.The temperature strips on the metal bars will allow you to “see” conduction in action.
39Conduction Investigation WS 19 – Conduction through MaterialsUse your Lab Sheet to record your investigation.
40Investigation Questions Please answer these questions on paper to attach to your lab sheet.What happened when the metal bars with temperature steps were placed in the hot water?How did heat get from the hot water to the temperature strip far above the water level?Did the metals conduct heat? Which metal is a better conductor of heat? What evidence do you have that supports your answer?Time for the Conduction Video!
41Conduction and Earth’s Surface The sun shines on Earth and the air gets warm. How does that happen?Draw an energy diagram for the following:Radiant solar energy strikes Earth’s surface. The surface absorbs the energy.Molecules in the surface materials increase their motion. Motion is heat, so the surface heats up.Molecules of gases in the air come into contact with Earth’s heated surface.If the surface is warmer than the air, energy from the surface will transfer to the air molecules. Air molecules will increase their motion. Motion is heat, so the air heats up.
42Energy Diagram – Does yours look like this? Radiant EnergyMolecules in surface increase in motionSurface absorbs energyMolecules in gases heat upMotion is heat so air heats upSurface heats upAir or Land heats up depending on which is warmer
43ConductionConduction is one way energy transfers to the atmosphere. When air molecules come in to contact with hot surfaces, they receive energy and get hotter.
45ReradiationThere is another, even more important way that heat energy enters the atmosphere. It is called reradiation.All matter radiates energy. I t is one of the great truths of nature. Hot matter radiates more energy than cold matter.When matter, like sand, soil, or water, absorbs energy from the sun, it warms up. When that hot matter reradiates that energy, the matter cools down. That’s why your containers of earth materials cooled down when you moved them to the shade – they reradiated the energy they had absorbed from the Sun.
46Reradiation continued… What happens to the reradiated energy? Most reradiated energy is not in the visible spectrum; it is in the infrared part of the spectrum. Infrared radiation is absorbed water and carbon dioxide molecules in the atmosphere. The energized water and carbon dioxide molecules then transfer their energy by conduction (contact) to the oxygen and nitrogen molecules in the air to heat the whole atmosphere.