MLB

Here's the list of necessary information to be included in your MLB:

All of your labs
Corresponding pictures when you feel its necessary
Whichever Handouts you like
Math Worksheets
Any of the Extra Credit assignments mentioned throughout the class

Each of these should have a matching equation and should be explained:
Scientific Notation
Thermal Expansion
Ideal Gas Law
Absolute Zero (maybe not an equation for this)
Specific Heat

If I left anything out i'll try to remember it.

P. S. @Steven, I did fix the kg per meter second squared in the ideal gas problems post on the blog, but not in the corresponding picture. Again I apologize for the mistake

Problems wherein we make pressure work!

There is one change here. I said cubic inches in problem 2 on your homework. I meant cubic meters. Also I do realize that the drawing doesn't quite make sense.



Thermodynamics: Problems 3 Ideal Gases Name____________



Please be sure to round each number to two places after the decimal, and all answers that require scientific notation should have one number before the decimal point and two after i.e.1.38x10-23. Points will be taken off for improper notation!

P = Pressure, measured in kilogram meters per seconds squared (kg/m*s2)
T = Temperature, measured in Kelvin
V = Volume, measured in cubic meters (m3)
N = The number of molecules in the gas
k = the Boltzmann Constant, or, 1.38 x 10-23 Joules per Kelvin (J/k) (Joules are kg*m2/s2)












1.) There is a chamber of gas that is 1 cubic meter, with a starting temperature of 298 K, and 5.8 x 1020 molecules. How much pressure is there?






2.) Will the pressure inside the chamber be able to lift a weight which weights 4 kilogram meters per second squared, and has a surface area of 2 square meters?





3.) What happens to your volume and pressure when the weight is lift upwards?




4.) At what volume will the weight be too heavy to lift (set you psi so that it will be equal to the weight and solve for v. don’t forget that the surface area still matters)?





5.) List two ways which would allow the weight to be lifted even higher?





6.) Imagine that at the bottom of this chamber there is a reservoir of water. How could we use this to increase the pressure in the chamber?




7.) Now we want to lower the weight, so we release half of the total molecules in the chamber. How high would the temperature need to be in order to lift the weight now?

Extra Credit

To those who might be looking for a little extra credit, and perhaps had already started their paper on the scientific method, you can earn a bit of extra credit by writing a short paper on the relationship between what we do in our labs, and how we transfer that to our classroom discussions. This is more of a philosophical question, which doesn't have one right answer, but I will judge you on the quality of thought that goes into the paper. Feel free to be creative, like the story about Fred the caveman scientist, but only do so if you think it helps explain your point.

Ideal Gas Problems

Here's a cleaned up version of the problem sheet I handed out today with a bonus extra credit! Blogger doesn't like exponents, but I think it's pretty clear which ones are supposed to be exponents

The Ideal Gas Law uses the formula Pv = NkT

P = Pressure, measured in kilogram meters per seconds squared (kg/m*s2)
T = Temperature, measured in Kelvin
V = Volume, measured in cubic meters (m3)
N = The number of molecules in the gas
k = the Boltzmann Constant, or, 1.38 x 10-23 Joules per Kelvin (J/k) (Joules are kg*m2/s2)

1.) If N*k/V = 1 x 10-2, and the pressure of a gas is 15 kg/m*s2. What would the temperature be?

2. Using the gas from problem 1, how far would the temperature need to drop to reach 0 degrees Celsius?

3. Using the gas from problem 1, if the number of molecules is 1.5 x 1022, what would its volume be?

4. If you increase this volume by 1.5m, and the temperature remains the same, what does the pressure become?

Bonus Extra Credit Question: In Problem 4, Show in detail how we could cancel out all of our units so that we reach the metric unit for pressure.

Problems 2: Linear Expansion

Here's a post for those who haven't finished this problem sheet yet

Formula for Linear Expansion: ΔL = aLΔt where:

ΔL = the change in length
a = the coefficient of linear expansion for the material
L = the original length
Δt = the change in temperature

1. A 10,000 meter steel railroad track with a coefficient of linear expansion of 12 x 10-6 per degree Celsius changes temperature from 18°C to 38°C. By how many meters will the railroad tracks expand?





2. Why do you think railroad tracks are segmented into short pieces?







3. The Eiffel Tower in Paris is 324 meters tall, and is made primarily of iron, which has a coefficient of linear expansion of 12 x 10-6. The coldest temperature ever recorded in Paris was 1°C, and the hottest was 99°C. What is the change in length that the tower has experienced in its lifetime?







4. By how much would you need to heat a 10 foot bar of zinc to make it expand by one inch? The coefficient of linear expansion of zinc is 30 x 10-6 per degree Celsius.







5. A metal bar changes in length by 1 meter with a 150 degree Celsius change in temperature. It’s coefficient of linear expansion is 25 x 10-6 per degree Celsius. What is the metal bar’s original length?







6. An unknown metal alloy is being tested to discover its thermal properties to see if it is suitable for use as a component in an aircraft wing. The alloy is formed into a bar measuring 1 meter in length, and is then heated from its starting temperature of 30 degrees Celsius to a final temperature of 100 degrees Celsius. The length of the heated bar is measured to be exactly 1.002 meters in length. What is the coefficient of thermal expansion of the alloy?







EXTRA CREDIT:

7. The aircraft wing from problem 6 experiences temperature extremes that span 210 degrees Celsius. The component for the wing will have a length of exactly 3 meters. Testing indicates that the aircraft wing will remain stable only if the component never expands to a length larger than 3.017 meters. If the component is made from the metal alloy in question, will it meet this requirement?

Here's the video I mentioned during class

MLK day (Edit)

If you're interested, here's a link to some video interviews and speeches of Martin Luther King Jr.. I hope you get a chance to listen to a speech or two of his, because quite frankly, he's awesome.

http://www.dalnet.lib.mi.us/king/ 

Sorry, forgot to post the link. It's up now.

Problems on Thermal Expansion

1.) There are two narrow tubes filled with liquid to 5 cm. One is filled with water, which has a coefficient of 69 x 10-6/Co. The other is filled with mercury which has a coefficient of 61 10-6/Co. If both tubes are heated by 20 Co, which one will expand more. By how much?









2.) How do thermometers work?∆∆∆





3.) Two pieces of metal of length 0.2 meters are fused together. When both are heated from temperature 20 degrees Celsius to 43 degrees Celsius we observe the length of on metal has gone from 0.2 to 0.20568, and the other has risen to 0.21. What are the coefficients of each metal?






4.) We have been using the equation from linear expansion, but now we want to look at how the volume of a body expands. The equation for volume expansion is ∆V =Vβ∆T. Looks familiar no? β is our coefficient of volume expansion, which is just like α, except instead of in 1 direction, volume expands in 3 directions. In short β = 3α . What would the thermal expansion be for a block of steel (coefficient 11.0 x 10-6/Co) that has a starting volume of 2 cubic meters, if you heat the block up by 200 degrees Celsius?




Extra Credit: On a hot day in Las Vegas, an oil trucker loaded 37,000 liters of diesel fuel. He encountered cold weather on the way to Payson, Utah, where the temperature was 23 degrees Celsius lower than in Vegas, and where he delivered his entire load. How many liters did he deliver? The coefficient for volume expansion for diesel fuel is 9.50 10-4/Co. and the coefficient for the linear expansion of his steel truck tank is11 10-6/Co.

Scientific Notation

Just in case we forget how to do all this business, here is a little thing i found online that should serve as a reminder.

Scientific Notation Review

Scientific Notation was developed in order to easily represent numbers that are either very large or very small. The Andromeda Galaxy (the closest one to our Milky Way galaxy) contains at least 200,000,000,000 stars. The number of stars in the Andromeda Galaxy can be written as:
2.0 x 100,000,000,000

It is that large number, 100,000,000,000 which cause the problem. But that is just a multiple of ten. In fact it is ten times itself eleven times:
10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 = 100,000,000,000

A more convenient way of writing 100,000,000,000 is 1011. The small number to the right of the ten is called the "exponent," or the "power of ten." It represents the number of zeros that follow the 1.

Though we think of zero as having no value, zeroes can make a number much bigger or smaller. Think about the difference between 10 dollars and 100 dollars. Any one who has balanced a checkbook knows that one zero can make a big difference in the value of the number. In the same way, 0.1 (one-tenth) of the US military budget is much more than 0.01 (one-hundredth) of the budget. (Though either one is probably more money than most of us will ever see in our checkbooks!)

So we would write 200,000,000,000 in scientific notation as: 2.0 x 1011

This number is read as follows: "two point zero times ten to the eleventh." There are some rules for expressing numbers in scientific notation:

Rule #1: There are two parts to the number, separated by a multiplication sign. The first is called the coefficient (2.0) and the second is called the power of ten.

Rule #2: The first number will ALWAYS start with a digit that is between 1 and 9, and will NEVER be zero.

Rule #3: The decimal point will ALWAYS follow the first digit.


How Does Scientific Notation Work?

As we said above, the exponent refers to the number of zeros that follow the 1. So:

101 = 10;
102 = 100;
103 = 1,000, and so on.

Similarly, 100 = 1, since the zero exponent means that no zeros follow the 1.

Negative exponents indicate negative powers of 10, which are expressed as fractions with 1 in the numerator (on top) and the power of 10 in the denominator (on the bottom). So:
10-1 = 1/10;
10-2 = 1/100;
10-3 = 1/1,000, and so on.

This allows us to express other small numbers this way. For example:

2.5 x 10-3 =
2.5 x 1/1,000 =
0.0025

Every number can be expressed in Scientific Notation. In our first example, 200,000,000,000 should be written as 2.0 x 1011. In theory, it can be written as 20 x 1010, but by convention (Rule #3) the number is usually written as 2.0 x 1011 so that the lead number is less than 10, followed by as many decimal places as necessary.

It is easy to see that all the variations above are just different ways to represent the same number:

200,000,000,000 =
20 x 1010 (20 x 10,000,000,000)
2.0 x 1011 (2.0 x 100,000,000,000)
.2 x 1012 (.2 x 1,000,000,000,000)

This illustrates another way to think about Scientific Notation: the exponent will tell you how the decimal point moves; a positive exponent moves the decimal point to the right, and a negative one moves it to the left. So for example:

4.0 x 102 = 400 (2 places to the right of 4);
While 4.0 x 10-2 = 0.04 (2 places to the left of 4).

Note that Scientific Notation is also sometimes expressed using the symbol E (for exponent), meaning “times ten to the”, as in 4 E 2 (meaning 4.0 x 10 raised to the power of 2). Similarly 4 E -2 means 4 times 10 raised to -2, or = 4 x 10-2 = 0.04. This method of expression makes it easier to type in scientific notation and is the standard method used in calculators.

Multiplication:

When multiplying numbers expressed in scientific notation, the exponents can simply be added together. This is because the exponent represents the number of zeros following the one. So:

101 x 102 = 10 x 100 = 1,000 = 103
Checking that we see: 101 x 102 = 101+2 = 103
Similarly 101 x 10-3 = 101-3 = 10-2 = .01
Again when we check we see that: 10 x 1/1000 = 1/100 = .01

Look at another example: (4.0 x 105) x (3.0 x 10-1).

The 4 and the 3 are multiplied, giving 12, but the exponents 5 and -1 are added, so the answer is:

12 x 104, or 1.2 x 105.

Let's check: (4 x 105) x (3 x 10-1) =
400,00 x 0.3 =
123,000 =
1.2 x 105.

Interesting note: another way to see that 100 = 1 is as follows:

101 x 10-1 = 101-1 = 100.
It is also: 10 x 1/10 = 1.
So 100 = 1

Division:

Let's look at a simple example:
(6.0 x 108)
------------
(3.0 x 105)

To solve this problem, first divide the COEFFICIENTS: 6 by the 3, to get 2. The exponent on the power of 10 in the denominator (the bottom) is then moved to the numerator (the top), reversing its sign and then adding the two numbers together. (Remember that little trick from your old math classes?) So we move the 105 to the numerator with a negative exponent, which then looks like this:

2 x 108+(-5)

All that's left now is to reduce this expression by adding the exponents. So the answer is:

2.0 x 103 or 2,000

Ice Melting Lab

I didn't think a proper handout was necessary for this short demonstration, but I'll write a little something to help with your writeup over the weekend. Yours shouldn't be longer than a page or so.

In the Ice Melting demo we are concerned with two things. 1. the way in which heat is transferred to other materials. 2. which materials conduct heat efficiently. The answer to the first question is the zeroth law of thermodynamics. That's not very helpful, but I'll put down a definition according to my text book, "Every body" (not everybody, though that is also true) "has a property called temperature. When two bodies are in thermal equilibrium, their temperatures are equal. And vice versa." Said otherwise, so long as two bodies in a closed system have different temperatures, there will be a transfer of heat i. e. they will not be in thermal equilibrium. A third way of saying it: When  enough heat is transferred so that two bodies, which are in contact, are the same temperature they are considered to be in thermal equilibrium. Until thermal equilibrium is reached they will transfer heat betwixt themselves.

Whew, got it? If not there is a comment section for you to ask me something, or wait till class on Monday.

The second part is simpler I think. In the second part we are simply measuring which kinds of materials of more capable of transferring heat quickly from one place to another. A material which 'conducts' heat well, like our metal plate, is able equalize temperatures quickly, whereas a poor conductor, like the Styrofoam, absorbs the cold of the ice only on one small part of it. 

Put the two parts together and you have something like this: 1. Two bodies in contact with each other will transfer heat until their temperatures are the same. 2. Some materials transfer heat quicker than others. 3. Therefore when bodies of two different temperatures are in contact with each other, bodies that are able to quickly transfer heat i. e. conductors, will manage to gain thermal equilibrium faster than poor conductors.

I hope this helps. See you all soon.

Conductivity

Here's a longer list of  the conductivity of various materials. All of them are measured at a specific temperature, because conductivity changes when materials are hotter or colder. The W/mk is the unit for thermal conductivity which is watts per meter per Kelvin. Don't worry too much about the units.

Thermal conductivity @20° C in W/mK

Diamond          1000

Silver    406

Copper            390

Gold     314

Aluminium        237

Brass    109

Iron      79.5

Steel     50.2

Lead    34.7

Aluminium Oxide          30

Stainless Steel   16

Mercury           8.3

Quartz  3

Marble 3

Sand (saturated)           2.7

Ice       2.1

Pyrex 7740      1.005

Glass,ordinary  0.8

Concrete          0.8

Water   0.6

Brick, red         0.6

Wood  0.4

Sand (dry)        0.35

Nylon 6            0.25

Methanol          0.21

Hydrogen         0.172

Olive oil            0.17

Alcohol            0.17

PVC    0.16

Gasoline           0.15

Brick,insulating 0.15

Leather 0.14

Wood  0.12

Snow (dry)       0.104

Silicone oil        0.1

Asbestos          0.08

Cork    0.07

Foam glass       0.045

Wool felt          0.04

Fiberglass         0.04

Polystyrene (styrofoam)            0.033

Plastic insulation materials         0.03

Cotton  0.03

Air       0.025

Oxygen            0.0238

Nitrogen           0.0234

Polyurethane     0.02

Formatting

I do know that some of the formatting on various posts is inexcusably bad. No promises, but if it's fairly simple, I'll try to fix it over the weekend. Otherwise, we may simply have to deal with the discrepancies between word and blogger formatting. Apologies.

Lab # 1 Our Very First Handout

Lab #1: The Sensation of Heat

Introduction:

We are trying to discover something about the way we perceive heat.  Upon what does our sensation of heat rest?  To find a way into this question we will use the scientific method.

Materials:

The air                                                                                      – symbol: A

Wood (cabinet doors)                                                                          – symbol: WD

The classroom wall                                                                              – symbol: DW

Glass (specify if you use a window, the fish tank or the cabinets–           - symbol: G

The metal leg of your chair                                                        – symbol: L

The top of the table                                                                               -symbol T

Our Hands                                                                                           -symbol H

Temperature strips

Procedure:

Using your entire palm as your ‘warmth sensing device’, feel each of the objects listed above for 1-5 seconds (enough to get a good report from your warmth sense but not long enough to let the heat from your hand warm the object too much).

Really pay attention to the sensation of warmth or coldness for each object, then put them in order of “Warmest” to “Coldest”, with #1 as the warmest and #7 as the coldest:

#1:_____________________ (warmest)

#2:_____________________                        

#3:_____________________                         

#4:_____________________                         

#5:_____________________                          

#6:_____________________                         

#7:_____________________ (coldest)          

When you are done rating the materials, go to the board and record your results in a column using the symbols provided in the materials section.

Dip you hands in water that is at room temperature. Let them sit for a little while. Try touching the objects again and noticing any changes in how they feel, heat wise. Try touching 1 dry hand with the wet one. See how the sensation differs.

Now dip you hands in the cold water for 30 seconds or so. Those squeamish about cold don’t have to do this. After your hands have adjusted to the water try touching the same objects and rating them again. Also notice if some objects feel warmer/colder than they used to. If your hand warms up too much, return to the cold water to test again. 

Try doing the same with warm water.

Once all observations have been recorded, we will get an assessment of the temperature of each object with the help of some thermometer strips.  Record the temperatures reported by the thermometers in the last column of the chart below.

Now you will need to copy from the board the entire class’ results, to compare with your own.  This helps us get a more comprehensive picture of the experiment because we don’t have to rely on any single person’s results, which may be wrong.  Use the table below to record the entire class’ results:

Put YOUR results in column 1. Record the actual thermometer temperature reading in the last column.

Warmest	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	Temp
Neutral
Neutral
Coldest

                                                                                                                                                                                     

Things to include in your analysis/conclusions section of your writeup:

Why might some of the objects feel warmer than others?

Did you expect certain objects to be warmer or cooler than others?  Why?

Is there a discrepancy between what you experienced and what the thermometers report or not?  Explain.

Can you make any reasonable conclusions about your sense of warmth? (What are the factors that play into this sense?  In other words, what are all the things that, if they changed, would change our sensation of warmth?)

Another Essay on Method

The Scientific Method: an Introduction                                                        By Seth Miller

 

What distinguishes a scientific theory from a non-scientific theory is that a scientific theory must be refutable in principle.  A set of circumstances must potentially exist such that if observed it would logically prove the theory wrong.

Here is a simplified version of the logic of the scientific method, see the flow chart on page 3 for more detail:

We encounter a phenomenon with our senses, and a question arises out of our observations.

Through a free, creative process, a hypothesis is generated that, if true, would at least partly explain why the particular phenomenon occurred to the exclusion of others.

On the basis of this hypothesis, an experiment is logically deduced that, when carried out, will result in a set of particular observations that should occur, under particular conditions, if the hypothesis true.  Data and observations are gathered from the result of the experiment and are recorded.

If those particular expected observations do not occur, then we are faced with several possibilities: our hypothesis needs to be revised, or there was some source (or sources!) of error that interfered with the gathering or analysis of the data. If the particular observations do occur, then we gain some confidence in our hypothesis.  The next step is then to form an alternate experiment that will test a new element of the hypothesis.

 

Summary of the Scientific Method:

We have a question for the world

We generate a hypothesis about it

We test our hypothesis with an experiment

We check our procedure and analysis for errors, and revise our hypothesis if necessary

We continue the cycle with a new or revised experiment

  

The actual process often involves a great deal of insight and creativity. Keep in mind, though, that without a disconfirmation being possible in principle, a belief is not acceptable as even a potential scientific hypothesis. There must be a possible concrete test.

Summary

A scientific theory must be testable. It must be possible in principle to prove it wrong.

Experiments are the sole judge of scientific truth.  (There are other kinds of truth!)

Scientific method: observations, hypothesis/theory, experiment (test), revision of theory, new experiment

 

1. The scientific method begins with a hypothesis, but as evidence for the hypothesis accumulates, the hypothesis becomes a model, and finally with widespread acceptance it becomes a full scientific theory.
2. A correlation between two things does NOT prove one thing causes the other. The second thing could cause the first or some other underlying factor could cause the correlation.
3. Scientists have to be very careful to rule out other possible underlying factors before concluding one thing causes something else.
4. Though scientific proofs are not known with absolute certainty, enough evidence can be accumulated to be reasonably certain.
5. No matter how much evidence we have for a conclusion, the conclusion could still conceivably be false.
6. The more positive cases in favor of a hypothesis, the stronger the hypothesis is.
7. The most logically sound samples are those that are representative of the entire set.
8. It is possible to make true conclusions from false assumptions.
9. A hypothesis can only be confirmed but it cannot be proven absolutely true.
10. Even though a scientific hypothesis cannot be proven absolutely true, that does not mean that it must be false.
11. Science is carried out through human effort and is therefore subject to all of the best and worst of cultural biases existing at the time.
12. Though the assumption is not necessary for science, many scientists assume that science needs to consider only the physical, concrete objects around us.
13. Some scientists assume that thought or consciousness is the most fundamental reality.
14. Possible ways of knowing: testimony, authority, revelation, mystical visions, scientific method.
15. Observational experience is a crucial part of scientific knowledge.
16. No matter how much logical deduction and mathematical analysis is used, the scientific theory must be checked against the real world to confirm the theory.
17. However, the exploration of the implications of a logical train of thought is a vital part of the scientific process.
18. The best ideas are those that enable us to make connections between rational theories and our observations of the world.

The Scientific Method – the Basics (follow the link for the image)

http://www.alchemical.org/thermo/img/scimethod.jpg