We say temperature. Whats that mean . Something different at the atomic level, hot cup of coffee, cold cup of coffee. In the hot cup of coffee, theres more activity. The molecules are jiggling faster. They have more energy of motion. We got a name for energy of motion. What do we call it . Kinetic energy. Kinetic energy. Theres more Kinetic Energy in the molecules in a hot cup of coffee than a you know that. Thats what it means to say that somethings hot, that it has more energy. We might say more thermal energy. More strictly speaking, well say more internal energy, more energy internal to the system. So theres much more internal energy in a hot cup of coffee than a cold cup of coffee. Whats got more internal energy, a hot cup of coffee or an iceberg floating down at the antarctica . Check your neighbor for an estimate. A humongous iceberg or a small hot cup of coffee which has the more internal energy . All the energy combined what would it be, gang . Yeah, the iceberg is frozen. How many say the hot cup of coffee still has more Kinetic Energy of all those molecules and those zillions and zillions come on, no, its the other way around, gang. [laughter] it turns out theres more internal energy in the humongous icebergs simply because there are more molecules jiggling, you know . Add up all the energy, youre gonna get a greater amount, okay . But when we talk about the energy per molecule, were talking about an idea that begins with t. Try it. Temperature. Temperature, yeah. Temperature has to do with the per molecule, okay . So theper molecule in a hot cup of coffee is a lot more than a heat per molecule in a hunk of ice. Isnt that true . Yeah. So we see theres adifference between temperature and total amount of energy. Temperature is an average, energy per molecule, kind of, yeah. We measure internal energy or any kind of energy in joules, or in heat units calories. Calories and joules are same, same. What is it . 4. 186 joules equals 1 calorie, Something Like that. But calories and joules are both a unit of energy. And temperature is measured in degrees. Degreeshow hot something is has to do with number of degrees. And thats different all together. It turns out that number of degrees that the amount of temperature has to do with the Kinetic Energy of motion. Well, usually, things when you heat them up, they expand. Most things will expand when heated. Liquids, gases, solids all expand. Guess which expands more, a gas or a liquid for the same change in temperature . Gas. Well, it turns out the gas. I can take a balloon and hold it over a stove. You could see that thing grow. If i take a a gallon of water and hold it over a stove, you dont see it grow very much. It does. And how about solids, how do they expand compared to gases . Not so much, but they expand nevertheless. So liquids expand because liquids expand when theyre heated. You could make thermal meters. Thermal meters. Let me show you an example of one. You might do this in the lab part of the class. You might have a glass tube like this. And in that glass tube, you have some mercury or some alcohol, colored alcohol. You have it in here, say, like that, okay . And it might come up to this particular level. Now, what you do as you put that thermal meter, which is a hunk of glass about this long with a reservoir at the bottom. You put that in a bath of ice cubes that are melting, melting ice. When you do that, the temperature of this becomes the same as the temperature of this because the slow moving ice molecules or slow moving water molecules over here impart only a Little Energy to here, or if this is hotter, by the way, it would send energy this way and heat up the water, you know . You cant have you thermometer too big. How about you get a thermometer this big and youre measuring this much water . Come on, whos measuring what, right . In fact, you know, people say a thermometer measures its own temperature. And thats true because any two things put together will come to the same temperature. And thats what happens here. So at zero degrees, thered be a certain elevation of the liquid in there. And you could take a little glass file and you could put a little mark there, if youre in the lab part of the course, and say thats the level that corresponds to this particular temperature of water. Now take that ice out of there, and take the water and heat it up until its boiling. Boiling water, okay . Boiling water, whats the boiling water molecules do to that glass . Bam, bam, bam, theyre really hitting. Theyre hitting with a lot of Kinetic Energy. And they bang into the glass with a lot of Kinetic Energy. And what do the molecules on the glass do . They start banging too. What do they do to the neighbor . Bang, bang, bang, it cascades right through. Next chapter, well call that conduction, where the Energy Cascades with molecular impact, bang, bang, bang, right . And finally, what do you know about liquid in there . That stuff is being shaken too. And when its shaken, whats that do . It climbs the tube. It climbs the tube. Climbs, climb, climb, then it finally settles off and stops. And guess where you make a second scratch . One guess. There. No, not down here. Not up here. Guess, gang. Right here. You put a scratch right in there, okay . Now, you got and you can call this the temperature of boiling water. And we can call that 100. We can call this scratch down here zero. Now, we got to make 100 scratches evenly spaced. So we get a hundred grades, a hundred grades. Do you guys know what the prefix a hundred is . Whats a hundredth of a dollar . Its a cent. No, not a penny. A what . A cent. A cent, okay . So we call this a centigrade thermometer. Centigrade, because 100 equals centi, huh . So we got a hundredth grade, a centigrade thermometer. So we measure these things in centigrade degrees. See what im saying . So if you take this and put this in some other bath of water, and the level comes up to the same, you know it has the same temperature as the initial one. So thats a centigrade thermometer. Now, in america, we dont always use the centigrade thermometer. Americans are a little bit more innovative, a little bit more maybe off the wall sometimes. American type do this, repeat the same experiment. And what the american type does is the american type put us in here and gets a scratch there. And he doesnt have to call it zero. You call any number you want, really . So long as you make them all the same way. Give me a number, a random. 32. All right, 32. You could call that 32, okay . I mean, whats so special about zero, yeah . Now, you put this in the boiling water, in the 32, bang, bang, bang. Now, you put it in boiling water, bang, bang, bang, were really hitting, huh . Orclimb up, scratch, if you want to put a hundred there. If you want to wimp out and put a hundred like everyone else does, go ahead. But lets suppose you say, lets get off the beaten path. Take anygive me a number, random, any number. 212. All right, 212. All right, 212. All right. Now, what do we call that thermometer . An american thermometer, okay . [laughter] well, that and what were saying is the boiling point of water is 212 degrees and the Freezing Point of water is 32 degrees, okay . Now, here is the problem, gang. You got to cut up equal number you got scratches in there. How many scratches are you gonna have between 212 and 32 . And you cant do it. Anyone got a calculator . Nobody . Anyone do it, maybe pencil and paper . How many scratches between here and here . This requires an arithmetic operation. It requires taking 32 away from 212. The two is all right, but look at the three. You got to subtract the three from the one. You got to do some carrying. [laughter] oh, let me tell you, gang. Ive done it before. Its 180, 180. So you got 180 scratches. Does anyone know what the prefix 1 180th is . A fahren, thats right. Engineer types know that. Thats a fahren. So we call this a fahrengrade thermometer, okay . Ever hear of a fahrengrade . No. We dont call it fahrengrade thermometer because we named this thermometer after the man who invented the scale. In honor of him, we name it for him. So its not a fahrengrade. Does anyone know the name of that guy . James j . Thermometer. [laughter] james j. Heit. Mr. Heit is the one that done that, so we call it a fahrenheit thermometer. Do you believe in this . Im just toying around with you guys over there, okay . But anyway, this is fahrenheit thermometer is measured in smaller degrees, in small degrees. You got 180 of those suckers in between freezing and melting, boiling point. In the celsius, you got 100 itll spread out more. So whats more accurate to the degree, fahrenheit or centigrade . Fahrenheit. Fahrenheit, you see, because in centigrade, you got to deal with more fractions. But fahrenheit has more spaces, finer tuning. So those are the two thermometers. Then theres another that well take about when we get up to thermodynamics and thats called the kelvin scale. And the kelvin scale is named after some dude by the name of james j. Scale. Scale, you got it. You got it, all right. So we have those kinds of ways of measuring temperature, the average Kinetic Energy per molecule of things. Heres a nice distinction between temperature and internal energy, or, loosely speaking, heat content. This used to bother me when i was a kid. You know those 4th of july sparklers . You light them and they [makes noise] and all those white hot sparks going out. And do you know what the temperature of those sparks are . More than 1,000 degrees celsius, more than 1,000 degrees. Is that hot or cold . Hot. Cold. H, no, no, no, begin with a h. [laughs] hot, okay. Those are hot sparks, gang, over 1,000 degrees celsius. Ever see little kids with those little sparks at home, like, hey, look at sparkler, honey, thats gonna dance sparks bouncing off the kids eyeballs and his cheeks and everything. And the kid does the kid scream . The kids okay. And i said, wait a minute. The temperature of those sparks is white hot temperature, enormously High Temperature, how come the kid aint hurt . And it has to do with the definition of temperature, proportional to energy per molecule. Every molecule got a humongous amount of energy, but how many molecules in that little spark . Not so many. So whats the total energy of that spark . Not so much. Below the kids threshold of feeling. So although the temperature is hot, the heat content, the internal energy of the spark is very low. Later on, well do a similar thing. Im gonna rub a balloon against my head, and im gonna tell you guys, this balloon got, like, thousands of volts. But well learn there that voltage is sort of like electrical pressures. Its energy per charge. Not many charges, so not much total energy. With the sparkler, not many molecules, so not much total energy burning the face. So temperature and heat content or internal energy, two different things. And by the way, we got a definition for heat that departs from the commonplace definition you have on the outside. And that is we say that heat is the energy that flows from one object to another by virtue of a temperature difference. So heat is always energy in transit. Strictly speaking, when the physic talks about heat, the physic is talking about energy in transit. Total amount of energy, physic are talking about internal energy. And the energy per molecule, the physic are talking about an idea that begin with a check your neighbor. It begins with a t, gang. Try it. Temperature. Temperature, temperature. Its the difference between temperature which is measured in degrees and heat which is measured in calories or joules. Got such thing . Different things heat up different rates. Youre at home, you get your stove. If its an electric stove, red hot. You take a frying pan, take a frying pan, put it on the stove, turn around, come back, put your hand on the frying pan. Oh, you burn yourself. Tattoo city, honey. You have burned yourself. Take that same frying pan, this time, pour a little water in it. Now, put the waterfilled frying pan on the stove, turn around, the telephone ring. [makes noise] whats itno, no, i dont want any aluminum siding on my house. Thank you anyway. Boom. You come back later, a few minutes later, put your hand on the water, huh, its okay . Its okay. Its okay . If you can do that, you can do that, its okay. Now, i got a question for you, which do you suppose has more internal energy . Which has absorbed more heat, the frying pan empty or the frying pan with the water in it . Think. Im not asking which has got the higher temperature. Im asking a different question. Im saying, which has absorbed the most heat . And your neighbor says. Whats the answer, gang . The water. The water has absorbed more heat. But you know what . Its not as hot. The temperature is not so high. So some substances will absorb an awful lot of heat for only a small change in temperature. Iron, put a little heat energy in it, whoop, the temperature soars. But water take a lot of heat energy to make the temperature higher. That has to do with temperature being the translational, backandforth motion of the molecules. When you heat up iron, the little electrons in there start zapping back and forth, back and forth, make the molecules move back and forth. Translational Kinetic Energy, that temperature goes up very quickly. But it turns out, when you heat up the water, that water is a funny little devil there. That water doesnt just shake back and forth. What the water does, it puckers in and out, in and out. And it gets intolook whats called, internal rotational states. And the Hydrogen Bonding makes them all fixed together so they wont shake so much, but they have the energy in a potential form. And so that doesnt drive the thermometer up very much at all. So you can put an awful lot of heat in water, and the temperature goes up a little bit. We say water stores an enormous capacity of heat for small temperature rises. Were talking about specific heat. Physics will say, hey, water got a high specific heat, means itll take in a lot of heat for a small temperature change. Thats why you use water in your radiator in your car. What do you want the water to do in your car . You want it to absorb that heat energy from your car, so it doesnt melt, right . And so a little bit of water will absorb a lot of heat energy. And the temperature doesnt go right and boil away on you either. It turns out the water will absorb a whole calorie of heat energy for every gram. It only goes one temperature to onedegree temperature change, one celsius degree. Specific heat of water, one calorie per gram degrees in celsius. So water, a big specific heat compared to other things. You can reach in an oven and take out with your bare hands an aluminum dish. The tv dinners, youve done that. You cant hold on it for a long time, but you can take it out quickly and put it down, then your hands are okay. Because it turns out, what . That aluminum dish has not absorbed as much energy for its High Temperature change as Something Like water would. Or when youre eating food, some foods you eat, you can eat very, very hot comfortably. Theres not very much energy in there. In some foods, especially with the water, like the inside of pie filling, you eat it, and, ooh, youll burn yourself, because that High Temperature has an awful lot more energy in it than the than say Something Like the aluminum foil on a tv dinner, Something Like that. Different things have different specific heats. I know water has a high specific heat. I remember when i was a kid. When i was a kid, i grew up in the outskirts of boston. And in the wintertime, gang, it is cold. And upstairs, we had one radiator in the house, and that was in the bathroom. And the bedrooms are really, really cold. You had to get the heat from downstairs. It will come up by a process well call later call convection, okay . Or well have to come a little bit from that radiator and migrate into the rooms. Anyway, it was cold, and in cold nights, we had a way of getting through. What my mother would do is, downstairs in the kitchen, she would cook a great, big bucket of water. I mean, not a bucket but a great, big pan or what do you call it . Pail, you know what im talking a container, container, okay, a container of water. It would take a long time to heat that water up, gang, a long time to heat that water up. And shed take that water and shed pour it into a jug. And that jug was what we call the hot water bottle. And that jug was like a clay jug, and shed fill it really hot i mean, really, really high. And you put your feet on it, youre gonna burn. So we put a towel on there. And you go upstairs and you put it in your bed, you put it at the bottom, and you put your feet on it. And we had an old adage, that if your feet are warm, youre warm, okay . When your feet get cold at night, youre sleeping onyou can thats tough city, okay . But if you put your feet on that hot water bottle, its okay. And in the middle of the night, it gets so its not quite so warm, you reach down, you take the towel off, and you put your feet right on the bare, and you get all through the night. Its okay. I didnt know anything about physics then. But looking back, i could see water got an enormously high specific heat, meaning, an awful lot of calories in that jug of water. And those calories are delivered slowly and slowly through my feet. So it was kind of neat. So high specific heat for water. The high specific heat of water has to do with different climates throughout the world. Here, ive got a globe here. Lets take a look at this. Go over to england. Heres england right here. Go to england on a summertime. Hows the weather in england on the summertime, okay or not okay . Begin with a o. Its okay. Its tolerable. But, honey, england doesnt really get very much sunshine. Because if you keep your finger on england and turn the globe [makes sound] i cant do that now. Youre over here in labrador. Whats the climate like in labrador in the hudson bay, okay or not okay . Cold. Well, its relative. It depends what you call okay, okay . But, honey, it is. Begin with a c end with a d. Cold. Its cold. Its very, very cold, cold climate there. But you know what . Its the same latitude as england. So why . England is surrounded by what . Begin with a w. Water. Water. And that water has a high specific heat. And that water is really heated up down here by the equator, isnt it . Water is heated up down here all year round, right . And that water drifts north in whats called the gulf stream. I guess someone near the gulf must have named it, yeah . And that water drifts north. And how many will say, oh, that water must cool off real quickly. No, no, no, that water dont cool out quickly. That water migrates right up through here and comes off here in the north atlantic and there it settles. And you know what . The water does cool down. Conservation of energy. To say the water cools down is to Say Something else gottawu. Warm up. Warm up, all right, yeah. See that, gang . So when the water cools, the energy got to go somewhere and so it goes to the air. And the winds at these latitudes are westerly, and the winds go this way and warms up all of england. But look at poor labrador over here or all these regions up here way up in here. Thats up here. Man, theres no water thats cooling off. Now, i will submit on this side of the hudson bay. You should have a better climate, a warmer climate than on this side of the hudson bay because the winds are going this way. Same thing in san francisco. San francisco has palm trees. The same latitude is san francisco. Heres washington, d. C. Honey, the best they can do are cherry trees, okay . [laughter] no palm trees. The only palm trees in washington, d. C. Are in the hotel lobbies, okay . Right . But we have palm trees in san francisco, and why is that . Same latitude, same amount of sunshine per unit area, see . But it turns out, what . We got the gulf stream not the gulf stream weve got the ocean out here. Now that ocean, if that ocean in the wintertime cools down a little bit, whats the air do . You wu. Warm up. Warm up, okay . And if it blows this way, whats it hit . Begin with a cal forni so california is a much warmer place in the winter than east coast communities of the same latitude. Aint that neat, okay . In fact, any place thats surrounded by water has just about the same temperature all year round. How about the best place in the world, right here . [laughter] thats hawaii, huh . The Hawaiian Islands, okay . The Hawaiian Islands about the same temperature all year round, but not only the Hawaiian Islands. Iceland way up here has about the same temperature all year round, yeah. Surrounded by water, okay . When it tends to be cold, the cooling water would heat it up. When it tends to be hot, the warming water will cool it down. So water acts as a moderator. Arent you glad that water has a high specific heat . Yum, yum, it had to do with the world we live in, yeah . Something else about water, kind of neat too. Water is the only substance the only common substance that will expand when you change it from the liquid state to the solid state. Did you guys know that . See, ice will float on top of water. Why . During the freezing, the ice must have puffed out. The ice puffs out. And why does the ice puff out . You guys ever see snowflakes . Leave it after school today, and go out and catch a snowflake. Let them [laughter] fall on your sleeves, okay . If you got a black sleeve you look at the snowflake really carefully, hey, son of a gun, the snowflake got six sides. Hey, this one got six sides too. Hey, they all got six sides. I wonder why. Your friend said, well, theres probably no reason for that. Its just characteristic of snowflakes. And what do you say . Hey, there got to be a reason. And the reason for the six sidedness of the snowflakes has to do with the way the h2o molecules pack together in their least energy configuration. And as theyre all packed together and they form hexagons. You see that in the textbook . And this is on page 263. And they form these hexagon structures with an open space in the middle. So you know what that means . A snowflake takes up more room in the snowflake form than if you melt it and turn it back to water. You turn it back to water, the molecules will caved in and occupy that empty spot. Its like a brick building. A brick building occupies more space when its in its constructed configuration than if you shake it so hard, you shake all the bricks and they cave in. The pile of bricks is less voluminous than the brick building was before it caved. Same thing with ice, gang. So water forms an open structure in its crystalline form, and thats kind of nice. It makes ice less dense than water, and the ice will float. So you can go ice skating, gang. Some people are kinda good at facts and figures. Does anyone here know when it was that Christopher Columbus sailed for america . You probably dont be knowing that year. How many people happen to know the year from their history . Can i have a show of hands . One, two, three, four, five, six, six, seven, eight scholars. Okay. It happened to be 1492, gang. Do anyone happen to know when the declaration of independence was signed in the United States . Its a particular date. Some people have it engraved in their heads and some people say, oh, i dont need to be knowing such thing. When was the declaration of independence signed . Anyone know what year . Have a show of hands. I wanna see you is. Show of hands. Well, we got almost half the scholastic class here. It turns out to be 1776. Some of us are good for remembering figures and some of us arent. Lets try something different. The temperature at the bottom of Lake Superior, new years eve, 1900, does anyone in here happen to know what the temperature at the bottom of that lake was at that time . One, two, three, four, five, six, even less people than knew when the declaration of independence was signed. And what has happened the temperature happened to be, gang . Say again . Four degree celsiu four degree celsius. Youre right, four degrees centigrade, right. Celsius, centigrade, same, same gang. Thats right, right on. Does anyone happen to know what the temperature at the bottom of lake tahoe . Thats over a half kilometer deep. Lake superior is almost half a kilometer deep. But lake tahoe in california, does anyone here happen to know the exact figure of the temperature of the bottom of that lake right now . One, two, three, all of the same hands. Whats the answer, gang . Four degrees. Four degrees celsius, thats right, thats right, thats right. Hey, outside the building here when i came in, there was a big puddle. Does anyone happen to know what the temperature is at the bottom of that puddle outside right now . No, it aint four degree celsius. [laughter] no, no, no, no. Its not. The temperature of the puddle is the same as the temperature of the air outside, okay . Theyre all the same, but how about a deep body of lake, gang . Do you know why the bottom of those lakes are four degrees celsius all year round all the time . First of all, theyre at latitudes where theres fourdegree weather in the wintertime. So let me ask you a question. Oh, you dont know about four degrees yet. Four degrees. I got to tell you something about fourdegree water. Fourdegree water is like dense or not dense . Dense . Dense or dense dense . Dense dense. Honey, fourdegree water is the densest water you can get cause water has different densities at different temperatures. See, if you heat some water up, wouldnt the volume get more and more and more . You know thats true because if you put a pan of water on a stove and fill it brimfilled and then turn on the stove, whats the water gonna do, gang . Beginning with o, f. Overflow. Overflow. The water is going to expand, see, okay . So the water, when it expands, itll have more volume for the same weight, it will be what . Less dense. So density depends on temperature. But it turns out ice got less density than boiling water. Now, how come . Because it forms all those open structures. Im going to make a graph here and this graph is volume, volume of water versus temperature. Im gonna consider some ice water not ice, not solid ice ice water. And that ice water has a particular volume like this. Now there are two things gonna happen when i heat the ice water. Number one is, when you heat anything, the molecules will start jiggling faster, faster, faster and take up more room. So theres sort of an expansion, okay . Well just say, as the temperature goes up, the volume increases. Thats true of most everything that you heat up. Itll grow bigger and bigger the faster the molecules shake, okay . But Something Else happens with the water that doesnt happen with other fluids, other liquids. And what happens is those open it turns out in that zerodegree water, you got a whole lot of those open crystals, its like a microscopic slush. And that microscopic slush, when you start heating it, what does the slush do . [makes noise] it caves in. And when it caves in, does it take up more room or less room . Less. Less room. And so when you heat water, due to the microscopic slush thats in there starts caving in, the water starts to get down. And so you got two things going on, a cavein as temperature increases, and an increase in volume as temperature increases. Put them together, when you combine them, you get Something Like this. And right here, thats four degrees, four degrees above freezing has the least volume. See that . And then above four degrees, it starts to go up. You still got some ice crystals crunching in there, but this part here has overtaken it and it goes like that. So you have this dip in the curve which turns out to be very interesting, very interesting. That dip in the curve has to do with the fact that on these deep lakes like Lake Superior and lake tahoe, i dont care how cold the winter gets, gang, youre not gonna get any ice on those lakes. And lets see why. A shallow lake, yeah, but a deep lake, no. Ive been up to lake tahoe and after that ive asked the people, hey, how come you got no ice on the lake . Oh, its too deep. Go to lake donna down the road there, you got plenty. You go ice skating there. Youre not gonna skate in tahoe, gang. Tahoe never freezes over. How come . cause its too deep, which kind of begs the question, well, how come too deep means it wont freeze . So he says, hey, im not a physics type. Just keep moving, honey, okay . But lets look in, we are physics types and we wanna see if theres a reason why that deep lake wont freeze. And it turns out it has to do with what were talking about right now. Lets take a look. Heres the lake. Okay, let me try this. Heres the lake. Now lets suppose that lake is 10 degrees above freezing, so its not gonna whats the temperature which freezing takes place, gang . Zero. Zero. Okay, so if im gonna freeze some water, i got to bring it from 10 down to zero, yeah . Okay, lets suppose out here, this is the air, lets suppose its 50 degrees below zero. I mean, cold. And that cold air blows over the top of the lake, how many people think that cold air blowing over the top of the lake is gonna make the temperature at the surface go up . Show of hands. Good. Nobody. How many say, that cold air will probably make the surface temperature go down . Show of hands. Well, almost everylike hey, we got everybody . Does everyone think that . Have you got 50degreebelowzero air blow over you, youre gonna get colder, not warmer . Isnt that remarkable . [laugh] come on you, gang, theres nothing remarkable about that. But ill show you a remarkable consequence of that. It turns to nine. Well do it by incremental steps, nine degrees. The wind, eight, can you see that makes sense . Where do we got to get to . Zero, yeah . Zero. Okay. Do anyone see something unusual here . Let me ask you a question. If i take a rock and throw it in that lake, whats the rock gonna do . Float. How many say, oh, it will probably float . [laugh] the rock is gonna sink, man. And why is the rock gonna sink . Well, thats characteristic of rocks, just to sink. Come on, why does the rock sink . cause its more dense than the water, right . How about this fourdegree water . Whats it gonna do, gang . Beginning with an s, end with an ink. Sink. Sink. Sink to the what . Bottom. The bottom. Heres your fourdegree water down here. What takes its place . Beginning with a t. 10. 10. By now, its february, okay . Get the idea . Honey, were gonna need a long winter to get to that lake. But now its march. How much time do we have . We getthe thing, you get the idea. [laugh] what happened at four, honey . By now, its may. People, its may, were running out of winter. You cant get a deep, deep lake to get all four degrees. Before you can get any threedegree water, never mind zero. What are you gonna turn the whole lake to . Four. And lets suppose we have like a big meteor hit or something and we get, like, no sunshine for about four or five years then wed get Something Like this. You keep doing the same thing and pretty soon, after a couple of years of that, then it would all be four. Honey, thats a lot of energy taken away by that cold wind. When you get the whole lake four degrees celsius, then and only then, thats the first threedegree water that lake has seen, gang. Does it stay there or does it sink . It stays there because whats down below is more dense. The lighter, the less dense will float on top of the more dense. That makes sense . Watch. Now we got zerodegree water. Those of you who are sitting close today will see something that those in the back of the room might not see. But watch very carefully to what happens to the water at the top. [makes noise] do you see that . Did you guys see that . Did you see the crystals form . Again. [makes noise] see, its a little thicker . Did you see those crystals form at the top . [makes noise] do you see now why ice forms at the top of a body of water . Aint that neat . So now you start to get some ice and the ice floats on top of the other water. Do you see why you have to have although that only happens with the shallow. You go up to lake tahoe and you take a saucer full of water, put it outside your motel room, come in and play checkers, half a game and go back there, boom, that water is solid ice. And you look out at the lake and it stays water all the time. Now youd be saying, why . The reason for those sort of things. How come then, like, glacier waters rapids, like some are is only about, like, four or five feet deep. Say again, say again . How come some glacier waters like rapids is only about four or five deep. I know theyre moving, but how come they dont freeze cause theyre like ice, thats ice cold. How come moving water doesnt freeze . Yeah, how come moving water doesnt freeze . Well, sometimes moving water does freeze. You just usually see on the outside edges though, right by the land. You never see the whole thing freeze over. Yeah. That seem like a pretty easy question to answer, doesnt it . Wouldnt you expect your teacher to be able to be, oh, the reason for that is blah, blah, blah. Well, i dont think i can give you a good answer for that other than say that the crystals cant theyre not a good answer. Can we still be friends . [laugh] oh, that did it . Okay. Try another question. Give me one that i said i can answer. Okay. Hey, lets talk about this expansion and this expansion under different temperatures and everything. We got something here thats kind of neat today. Ted, could you give me a hand . Talk about low temperatures. Ted has brought over here some liquid nitrogen. This liquid nitrogen is about 190 degrees below zero celsius, really, really cold almost 80 degrees above the absolute zero temperature. Now, can we have a volunteer to jam their hand in there for about five minutes . [laughter] okay, nobody gonna do that, right . Okay, lets show how the lets take the lets show how the volume of something will change. Heres an airfilled balloon, gang. Okay, whats gonna happen to the volume when it gets cold . How many will say, oh, its gonna expand . Stand up. And what happens to the volume, gang . Look at that. Now, its gonna start to warm up the air temperature. What happened to the volume . What happened to the volume when we bring it above air temperature . Hang it a little closer, ted. Yeah. [laughter] lets try the flower. Theres a flower ted found out in the ground. Its kind of nice and limp, right . Kind of limp, isnt it . Okay. So what happens is you slow those molecules down. Why did it fizzle like that . Yeah, why did it fizzle like that . Whats going on . Oh, gang, did you see such a thing . Look at that, gang. If you stuck your hand in there and hit it against the table, would it do the same thing . Yes, yes, can we have a volunteer, please . [laughter] unfortunately, it would, yeah. Another one . Right. Would a pen break . You wanna try it . Yeah. Okay, teds got a little lets see if i can do this. I did this a long time ago. What was that . Now, i got a friend of mine, his name is Gerald Walker who does something that i dont have the guts to do. Gerald takes the stuff and drinks a little bit and blows out. I aint gonna do that, gang. [laughter] ted is doing pretty good, yeah . Guess whos got the courage of the two of us . Come on, try one. Heres where you get the bnta. What did you do . Did you eat it . Is it all right . Did you put it in your mouth . What will you do is hold it. Well, it isnt your tongue, put it over your teeth and then just blow over the top of it. I only drop, of course, i dont have any experience. I didnt say how you did that, ted. It will be you want me to oh, i have an extra one. Do you want me to do it first . You do it first. Let me look and see what youre doing. Okay. You pick it up. Yeah. [laughter] anyone hungry . Ive got one more. Well do this at the party, gang. Its a little cool, yeah. Thats why you dont stick it on your tongue for a long time but, again, the same story with the white hot spark, its not real cold for a long time. Here you go. Thank you, ted. Whole way, man. Whole way. [laughter] okay. Yeah, ivehow death defying going to be here. We got a penny. What do you suppose happened to the size of that penny that we put in here, gang . If you had some calibers, you measured the diameter, what would happen to the diameter when its cold, get larger or smaller . Smaller. Smaller. Theyll shrink, right . Is that water warm after a while its been out in the air . Oh, its not water. This is liquid nitrogen. Yeah, liquid nitrogen. Oh, darn. Does it warm up though after . Oh, yeah, its warmed up. Its boiling. Its boiling right now. Thats what this stuff is. Its boiling right now. Do you want to see if this gonna break, right . No. Thats gonna be so thats a little real. Now, do you want this back . Were gonna make our own. [laughter] copper is a very good conductor. Does the so when we cool things, gang, they expand or they contract . Question. Isnt that plastic container . Yeah. Is it brittle . Yes, it is very brittle, very brittle, yeah. See the frost in the outside . If you ever drop that, it will probably just crack. Hey gang, i want to leave you with a question. When we cool things, they contract. Right. When we heat things, they expand. If i heat this ring, get it really, really hot and im gonna do that next time. Next time, im gonna put it under the blowtorch and im gonna get it really, really hot. Would it become larger, smaller or stay the same . Lets suppose we did this as a test. I took the ring and lets suppose the ring right now will pass through the lets suppose the ball will pass through the ring. If i heat the ball up, will it still pass through the ring . No. Thats elementary. I would insult you if i told you to think about that for a long time, right . We know the ball is gonna get bigger. And if the ball gets bigger, it will never get through the hole if it just barely makes it now. Isnt that true . Heres the question i got for you. The next time we come in, im not gonna heat up the ball. Im gonna heat up the ring. And when i heat up the ring, will the ball be able to get through if it just gets through now . Will the hole become larger, smaller or stay the same size when i heat the ring . Think about that cause we got that for homework. Hey, you know what . You can do this as a test, experiment. Take a ring off your finger, put it on the stove, get it hot. Does the hole get bigger, smaller or stay and then jam it back in your finger and see. [laughter] no, no, not your finger, your kid sisters finger, all right . And see if the hole gets larger, smaller or stays the same and see if you can say hc for next time, gang, okay . Homework . As a homework. Catch you later, physics. [music] captioning performed by aegis rapidtext paul hewitt here, a few words. You know who we are and what were about has a lot to do with the influences in our life, the people who have influenced us. And i, like everyone, have had many, many influences. And i just wanna cite, oh, very few, just three or four here. I know when i was in high school, there was a counselor, edward gibbs, high school counselor, and he advised me to not take any academic subjects because i wouldnt need to, because he was aware of my talent for art. I was the guy that would paint the posters for the dances, make the cartoons in the yearbook and that kind of thing. And so he said i wouldnt have to take academic courses, so i took his advice and i didnt. And so in high school, i took no physics, no science. I did mathematics for boys in the freshman year, and there was a general science course and i thought it was wonderful. But thats about it for that. And another one of my influences was kenny isaacs. Kenny isaacs was a local boxing hero. And i was one of these kids that was getting beat up all the time by bullies. I wasnt much of a physical specimen. And kenny isaacs was he was the fighter of fighters. Everyone admired that guy. I remember going to lynn and watching him fight sometimes. I was about maybe 14 years old, 13, 14, and saying, wow, this guy is so great. I wish i could be there in his corner, be sort of the kid that comes up with the water bucket, you know, and helps him. This is a gladiator, no one beat him up. But anyway, kenny isaacs was a big influence because, to make a long story short, three years later, kenny isaacs was in my corner. And a fellow lived next door to me, eddie mccarthy, who was a professional fighter, 135pound, lightweight, very good guy. And he took me under his wing. But then he went off to the korean war. Just before he did that, he turned me over to a local boxing hero, kenny isaacs. And he told kenny, kenny, take young paul here under your wing. Hes my protege. Kenny did that. And i was gonna retire as soon as i won the flyweight championship of north america, but i never got that far. I got up to the silver medal for the aau in new england at the age of 17. And that was about it. After that, in the followup fight, getting ready for the nationals, i got knocked out, the end of that career. Another big influence on my life was burl grey, a sign painter that i met back in the late fifties. Burl was painting in miami and i was assigned to paint with him. No one else would paint with him because there was a rumor going around about him that he was, yeah, one of them. He was accused of being, and i found out for myself that old burl was an intellectual. And intellectuals didnt cut it at the sign painting circuit. Anyway, burl grey influenced me a lot. Hes the one that lit my fire to get into science. And many of the ideas i had about things were burl sort of demolished. He was a very philosophical type and he was a nontheist. And he, you know, convinced me that things were so much simpler if you took a more scientific view of the world and theres so much that were taught to believe or that we come to believe that simply isnt true. And how does one determine whats true or not . Do you find out when youre an old person ready to die that everything youve been doing is just junk . Well, you know, we each need a knowledge filter, sort of, to tell the difference between whats true and what isnt true. And burl convinced me that the best knowledge filter ever invented is science. And so i got into science. I went to school. I went to college, lowell tech in massachusetts, after doing a year of prep school cause i didnt take the recommended courses in high school, i had to do this, you know, make up for deficiencies. So burl was a big influence of mine. And then i went through it and i got a physics degree. And while getting that physics degree, it was very, very difficult for me. But there was a book i read when i was in graduate school in the summertime. It was wonderful. It was a book called basic physics by ken ford. And ken ford became my mentor and another big influence on me. And ken fords book, awesome. He told it like it is. Ken ford is a giant himself. He doesnt have a nobel prize but his friends do. Hes one of those type guys. He was the exec officer of the American Institute of physics. Im proud to say now, im very proud of him to have him for a personal friend. So he was a great influence on me. And now i find myself, my greatest satisfaction is to realize that i myself am an influence for other people. Im sort of a kenny isaacs or a burl grey or a ken ford to many students. And this many is with a capital m, thanks to the efforts of my friend marshall alenstein who has put together these videotapes a these dvds that spread my lectures from the classroom into the classrooms of many people. And so, its wonderful being that role model for other teachers and students. And whatever i can do to be a burl grey to other people, to let them see that perhaps a very Good Foundation for, hey, whats going on in the world, certainly, is science. So lets hear it for physics. Physics first, its a wonderful way to look at the world. It makes sense out of what ordinarily might be just too cplex to understand. Physics, i love it. I hope you do too
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