Quest for the Nobel Prize competition
HW: work on problem set, do WebAssign problems
Next week: Newton's Law of Cooling Lab, Titanic Lab
Test on Friday
Friday, February 29, 2008
Thursday, February 28, 2008
Thursday, Feb 28, 2008
Went over RA 15.1, RA 16.1
IB students went off in pairs to do the Power of the Sun lab in the courtyard using the 200 W light bulb. The focus of this lab is on handling the uncertainty calculations.
The rest of the students worked on the Thermal Concepts problem sheet.
By popular watched the first 15 minutes of the Bill Nye video on Heat.
Assigned WebAssign Chapter 15 due Sunday evening.
IB students went off in pairs to do the Power of the Sun lab in the courtyard using the 200 W light bulb. The focus of this lab is on handling the uncertainty calculations.
The rest of the students worked on the Thermal Concepts problem sheet.
By popular watched the first 15 minutes of the Bill Nye video on Heat.
Assigned WebAssign Chapter 15 due Sunday evening.
Wednesday, February 27, 2008
Wednesday, Feb 27, 2008
Collected Heat Capacity Labs
Reviewed topics from yesterday - conduction, convection, radiation
Showed how to estimate the average temperature of the Earth assuming 30% reflection. Calculated 257 K.
Showed Hewitt video on Change of State
Discussed heating curve of water with phase changes.
Handed out RA 16.1 - due tomorrow
Assigned WebAssign Chapter 15 - Heat Transfer - due Sunday night
Reviewed topics from yesterday - conduction, convection, radiation
Showed how to estimate the average temperature of the Earth assuming 30% reflection. Calculated 257 K.
Showed Hewitt video on Change of State
Discussed heating curve of water with phase changes.
Handed out RA 16.1 - due tomorrow
Assigned WebAssign Chapter 15 - Heat Transfer - due Sunday night
Tuesday, February 26, 2008
Tuesday, Feb 26, 2008
Collected RA 15.1. Graded it while students finished watching the Hewitt video on Heat Transfer.
Demonstrated the wax brightness lab and showed how to do calculations. Described the lab to calculate the power output of the Sun which we will do the next bright sunny day.
Reviewed with class conduction, convection, and radiation. Gave examples of convection and how it affects onshore and offshore winds.
Introduced Wien's Law and the Stefan-Boltzmann Law. Showed how to use Wien's Law to get the wavelength of maximum emission. Used the Stefan-Boltzmann Law to show how the Intensity vs Wavelength curve various with temperature. At higher temperatures the wavelength of maximum emission shifts towards shorter wavelengths but an object at higher temperature emits more radiation at all wavelengths.
Discussed colors of stars and showed the Intensity (W/m^3) vs wavelength curves for various temperature stars.
Calculated the wavelength of maximum emission for a human. Showed how to calculate the power radiated by a human assuming emissivity = 1.
Talked briefly about the concept of a black body which is an object that absorbs at all wavelengths and emits at all wavelengths. Stars can be approximated as black bodies.
Heat Capacity Lab due tomorrow.
Demonstrated the wax brightness lab and showed how to do calculations. Described the lab to calculate the power output of the Sun which we will do the next bright sunny day.
Reviewed with class conduction, convection, and radiation. Gave examples of convection and how it affects onshore and offshore winds.
Introduced Wien's Law and the Stefan-Boltzmann Law. Showed how to use Wien's Law to get the wavelength of maximum emission. Used the Stefan-Boltzmann Law to show how the Intensity vs Wavelength curve various with temperature. At higher temperatures the wavelength of maximum emission shifts towards shorter wavelengths but an object at higher temperature emits more radiation at all wavelengths.
Discussed colors of stars and showed the Intensity (W/m^3) vs wavelength curves for various temperature stars.
Calculated the wavelength of maximum emission for a human. Showed how to calculate the power radiated by a human assuming emissivity = 1.
Talked briefly about the concept of a black body which is an object that absorbs at all wavelengths and emits at all wavelengths. Stars can be approximated as black bodies.
Heat Capacity Lab due tomorrow.
Monday, February 25, 2008
Monday, Feb 25, 2008
Handed back Oleic Acid Labs - discussed uncertainty calculations
Lectured on Heat Transfer
Conduction: molecular collisions and collisions between loose electrons in objects that are in direct contact.
Introduced idea of temperature reservoir
Deduced equation for heat flow
Showed that temperature profile in a uniform conductor is a straight line
Solved a problem to find junction temperature at the junction of two materials
Generalized to say that if the temperature difference is great (for the same thickness), the thermal conductivity is small.
Demo with star of different metals. On which does the wax melt first.
Convection
Demo with hot and cold water volcanoes.
Started Hewitt video on Heat Transfer.
Handed out RA 15.1 - due Tuesday
Lectured on Heat Transfer
Conduction: molecular collisions and collisions between loose electrons in objects that are in direct contact.
Introduced idea of temperature reservoir
Deduced equation for heat flow
Showed that temperature profile in a uniform conductor is a straight line
Solved a problem to find junction temperature at the junction of two materials
Generalized to say that if the temperature difference is great (for the same thickness), the thermal conductivity is small.
Demo with star of different metals. On which does the wax melt first.
Convection
Demo with hot and cold water volcanoes.
Started Hewitt video on Heat Transfer.
Handed out RA 15.1 - due Tuesday
Friday, February 22, 2008
Thursday, February 21, 2008
Thursday, Feb 21, 2008
Showed Jearl Walker video on Leidenfrost effect.
Went over RA 14.2, RA 14.3.
Handed out lab sheet and assessment sheet for Heat Capacity Lab which students will do tomorrow (Friday).
Showed Hewitt video on Temperature, Heat and Expansion up to freezing pond.
Students have WebAssign problems chapter 14 to work on - due tomorrow.
Went over RA 14.2, RA 14.3.
Handed out lab sheet and assessment sheet for Heat Capacity Lab which students will do tomorrow (Friday).
Showed Hewitt video on Temperature, Heat and Expansion up to freezing pond.
Students have WebAssign problems chapter 14 to work on - due tomorrow.
Wednesday, February 20, 2008
Wednesday, Feb 20, 2008
Collected Oleic Acid Lab Reports, RA 14.3
Introductory lecture on Heat and Temperature
Temperature: Measure of how "hot" or "cold" an object is. On a microscopic scale, it is proportional to the random kinetic energy of the particles.
This idea is powerful. In a room full of air, all the molecules, on average, have the same KE. Since an oxygen molecule has more mass than a nitrogen molecule but they have, on average, the same KE, you can compare the average speeds of the molecules. The nitrogen molecule is moving faster by a factor of the square root of the ratio of their atomic masses.
Internal Energy: This is the total random energy of all the particles in a substance. It includes the random KE (jiggling, rotation, vibration) as well as associated PE due to vibration and intermolecular forces.
Heat: Energy that is transferred from one object to another due to a difference in temperature. Note that the Atlantic Ocean has way more internal energy than a cup of hot coffee but if you mix the two, energy will be transferred from the coffee to the ocean.
Temperature scales: Discussed Fahrenheit, Rankin, Celsius, Kelvin - what the temperatures are for each at absolute zero, freezing point of water, boiling point of water, and how you can sus out how to convert from one scale to another.
Showed a picture of the range of temperatures.
Discussed how absolute zero can be determined using a constant volume thermometer and extrapolating to zero pressure.
Heat Capacity, Specific Heat Capacity: This is a type of thermal inertia - a measure of how much the substance resists a change in temperature for a given amount of heat energy. The greater the heat capacity, the greater the thermal inertia and the smaller the change in temperature for a given amount of heat energy. Water has a large specific heat capacity = 4180 J/kg-K. Demo of heat capacity.
Lead had a much smaller specific heat capacity than aluminum since, for the same mass, there are many more atoms of aluminum. If you supply a quantity of heat energy, it has to be spread among the many atoms of aluminum, so each atom gets less energy and thus a smaller increase in temperature.
Showed how degrees of freedom affect specific heat capacity and showed a graph of when (at what temperatures) the rotational and vibration modes kick in for hydrogen gas. Because a diatomic gas has more degrees of freedom than a monoatomic gas, it has a greater heat capacity.
Discussed Heat Capacity Lab that students will do on Friday.
Linear expansion: Most substances increase in size when heated since the particles are jiggling more and take up more space. If you have a rod of length L, for a change in temperature delta T it will increase in length by delta L. If you have two identical rods, each will increase in length the same amount. If you put them together to make a rod twice a big, the expansion is twice as much. Showed how to derive the equation for linear expansion: delta L = alpha * L * delta T where alpha is the coefficient of linear expansion that depends on the material.
Demonstrated expansion using bimetallic strip (brass and steel) and ball and ring.
Derived area and volume expansion equations.
If you heat a hole, it also expands.
Demoed ivory soap and CD in microwave.
Homework: work on WebAssign problems.
Introductory lecture on Heat and Temperature
Temperature: Measure of how "hot" or "cold" an object is. On a microscopic scale, it is proportional to the random kinetic energy of the particles.
This idea is powerful. In a room full of air, all the molecules, on average, have the same KE. Since an oxygen molecule has more mass than a nitrogen molecule but they have, on average, the same KE, you can compare the average speeds of the molecules. The nitrogen molecule is moving faster by a factor of the square root of the ratio of their atomic masses.
Internal Energy: This is the total random energy of all the particles in a substance. It includes the random KE (jiggling, rotation, vibration) as well as associated PE due to vibration and intermolecular forces.
Heat: Energy that is transferred from one object to another due to a difference in temperature. Note that the Atlantic Ocean has way more internal energy than a cup of hot coffee but if you mix the two, energy will be transferred from the coffee to the ocean.
Temperature scales: Discussed Fahrenheit, Rankin, Celsius, Kelvin - what the temperatures are for each at absolute zero, freezing point of water, boiling point of water, and how you can sus out how to convert from one scale to another.
Showed a picture of the range of temperatures.
Discussed how absolute zero can be determined using a constant volume thermometer and extrapolating to zero pressure.
Heat Capacity, Specific Heat Capacity: This is a type of thermal inertia - a measure of how much the substance resists a change in temperature for a given amount of heat energy. The greater the heat capacity, the greater the thermal inertia and the smaller the change in temperature for a given amount of heat energy. Water has a large specific heat capacity = 4180 J/kg-K. Demo of heat capacity.
Lead had a much smaller specific heat capacity than aluminum since, for the same mass, there are many more atoms of aluminum. If you supply a quantity of heat energy, it has to be spread among the many atoms of aluminum, so each atom gets less energy and thus a smaller increase in temperature.
Showed how degrees of freedom affect specific heat capacity and showed a graph of when (at what temperatures) the rotational and vibration modes kick in for hydrogen gas. Because a diatomic gas has more degrees of freedom than a monoatomic gas, it has a greater heat capacity.
Discussed Heat Capacity Lab that students will do on Friday.
Linear expansion: Most substances increase in size when heated since the particles are jiggling more and take up more space. If you have a rod of length L, for a change in temperature delta T it will increase in length by delta L. If you have two identical rods, each will increase in length the same amount. If you put them together to make a rod twice a big, the expansion is twice as much. Showed how to derive the equation for linear expansion: delta L = alpha * L * delta T where alpha is the coefficient of linear expansion that depends on the material.
Demonstrated expansion using bimetallic strip (brass and steel) and ball and ring.
Derived area and volume expansion equations.
If you heat a hole, it also expands.
Demoed ivory soap and CD in microwave.
Homework: work on WebAssign problems.
Tuesday, February 19, 2008
Tuesday, Feb 19, 2008
Went over SHM test.
Went over RA 14.1.
Temperature scales: Fahrenheit, Celsius, Kelvin
Kelvin: don't say "degrees" Kelvin. Kelvin scale MUST be used if the temperature is and absolute temperature and not a temperature difference, as in the ideal gas law, PV = nRT
Internal Energy: Total energy of all the particles
Heat: Energy that flows from one object to another based on temperature difference
Temperature: Measure of how "hot" or "cold". Measure of the average random kinetic energy.
Difference between internal energy and temperature
Degrees of freedom: monoatomic, diatomic with rotational modes, metallic crystal with KE and PE
Heat Capacity: On average, energy is shared equally between all degrees of freedom and between all particles.
Collected RA 14.2
Handed out RA 14.3 - due Wednesday
Assigned WebAssign Chapter 14 due Fri
Oleic Acid due Wednesday
Went over RA 14.1.
Temperature scales: Fahrenheit, Celsius, Kelvin
Kelvin: don't say "degrees" Kelvin. Kelvin scale MUST be used if the temperature is and absolute temperature and not a temperature difference, as in the ideal gas law, PV = nRT
Internal Energy: Total energy of all the particles
Heat: Energy that flows from one object to another based on temperature difference
Temperature: Measure of how "hot" or "cold". Measure of the average random kinetic energy.
Difference between internal energy and temperature
Degrees of freedom: monoatomic, diatomic with rotational modes, metallic crystal with KE and PE
Heat Capacity: On average, energy is shared equally between all degrees of freedom and between all particles.
Collected RA 14.2
Handed out RA 14.3 - due Wednesday
Assigned WebAssign Chapter 14 due Fri
Oleic Acid due Wednesday
Friday, February 15, 2008
Friday, Feb 15, 2008
Collect RA 14.1
Redo on some problems on SHM test
Oleic Acid Lab, due Wed next week
Homework: RA 14.2
Redo on some problems on SHM test
Oleic Acid Lab, due Wed next week
Homework: RA 14.2
Thursday, February 14, 2008
Thursday, Feb 14, 2008 - Valentine's Day
Test on Chapters 10, 11 and SHM
Handed out RA 14.1 due tomorrow
Handed out RA 14.1 due tomorrow
Wednesday, Feb 13, 2008
Handed back AAPT test booklets.
Reviewed reading assignment sheet on scaling.
Answered questions and solved problems on SHM.
Worked out SHM problem for tunnel through Earth.
Derived equation for gravitational potential energy. Showed how it can be used to determine escape velocity.
Test tomorrow on Ch 10, 11, SHM
Reviewed reading assignment sheet on scaling.
Answered questions and solved problems on SHM.
Worked out SHM problem for tunnel through Earth.
Derived equation for gravitational potential energy. Showed how it can be used to determine escape velocity.
Test tomorrow on Ch 10, 11, SHM
Tuesday, February 12, 2008
Monday, February 11, 2008
Monday, Feb 11, 2008
Collected RA on density and Hooke's Law
Went over some of the WebAssign problems on SHM. Will give an extension for the assignment.
Showed how to measure small distances using a micrometer.
Students did BB Pancake Lab. Due Tuesday for extra credit, due Wed as last day.
Handed back Reading Assignment on density and Hooke's Law.
Handed back Excel spreadsheet lab sheets.
Went over some of the WebAssign problems on SHM. Will give an extension for the assignment.
Showed how to measure small distances using a micrometer.
Students did BB Pancake Lab. Due Tuesday for extra credit, due Wed as last day.
Handed back Reading Assignment on density and Hooke's Law.
Handed back Excel spreadsheet lab sheets.
Friday, February 8, 2008
Friday, Feb 8, 2008
Went to library computer lab. Students downloaded Excel spreadsheet from WebAssign (go to Communications). Note that there is an error in the spreadsheet - it is two pages long and I left my name on the second sheet. Students should enter their own names.
Students completed the spreadsheet lab on uncertainties that corresponded to the worksheet on uncertainties. Students printed out their results.
When done, students worked on a second spreadsheet for uncertainties for the Rocket Lab.
Students who had not taken IB Physics 1 started with the Introduction to Excel spreadsheet lab corresponding to the graphing of round objects lab.
Homework for Monday is to complete and hand in RA 11.2 (density and Hooke's Law) and to do the WebAssign problems on SHM.
Students completed the spreadsheet lab on uncertainties that corresponded to the worksheet on uncertainties. Students printed out their results.
When done, students worked on a second spreadsheet for uncertainties for the Rocket Lab.
Students who had not taken IB Physics 1 started with the Introduction to Excel spreadsheet lab corresponding to the graphing of round objects lab.
Homework for Monday is to complete and hand in RA 11.2 (density and Hooke's Law) and to do the WebAssign problems on SHM.
Thursday, February 7, 2008
Thursday, Feb 7, 2008
Collected Spring Constant Labs
Went over RA Chapter 10
Example of atom to football field.
Example of Milky Way galaxy to football field - calculated number of stars in galaxy.
Reviewed electromagnetic spectrum
Radio, Microwaves, Infrared, Visible (ROY G BIV), Ultraviolet, X-Rays, Gamma Rays
Used speed = wavelength * frequency to calculate wavelengths of AM and FM radio waves
Used E = mc^2 to calculate mass to energy
Collected RA Chap 11 Scaling, graded, and handed it back
Showed Hewitt video on scaling
Went over RA Chapter 10
Example of atom to football field.
Example of Milky Way galaxy to football field - calculated number of stars in galaxy.
Reviewed electromagnetic spectrum
Radio, Microwaves, Infrared, Visible (ROY G BIV), Ultraviolet, X-Rays, Gamma Rays
Used speed = wavelength * frequency to calculate wavelengths of AM and FM radio waves
Used E = mc^2 to calculate mass to energy
Collected RA Chap 11 Scaling, graded, and handed it back
Showed Hewitt video on scaling
Wednesday, February 6, 2008
Wednesday, Feb 6, 2008
Work Day
Allowed students time to finish Spring Constant Lab due Thursday
Students could also work on Pumpkin Lab part 1
Assigned WebAssign Chapter 11 SHM due Sunday 10 pm
Handed out RA11.2 due Thurs
Allowed students time to finish Spring Constant Lab due Thursday
Students could also work on Pumpkin Lab part 1
Assigned WebAssign Chapter 11 SHM due Sunday 10 pm
Handed out RA11.2 due Thurs
Tuesday, February 5, 2008
Tuesday, Feb 5, 2008
Lecture on Dealing with Uncertainty in Physics
Lectured on uncertainties:
1. If you have multiple measurements:
Find the average by: (M1 + M2 + ... + Mn)/n
Find the uncertainty by: (abs(M1-avg) + abs(M2-avg) + ... + abs(Mn-avg))/n
2. If you have one measurement of each quantity:
2a. Max Min method
Example of area of a rectangle
Max area = (L + uncL)*(W + uncW)
Min area = (L - uncL)*(W - uncW)
Avg area = (Max area + Min area)/ 2
Unc Area = (Max area - Min area)/ 2
2b. Method of Relative Uncertainty
This method cannot be used if the terms are added or subtracted but otherwise is powerful and easy to use
Used example of area of a rectangle
Area = L * W
Unc Area = A * (uncL/L + uncW/W)
If you have a complicated expression like: Z = (A^1/2) * (B^3)/(C^5)
you can use this method taking the absolute values of the exponents as coefficients in the relative uncertainty equation: uncZ = Z*((1/2)*uncA/A + 3*uncB/B + 5*uncC/C)
Handed out practice sheet on uncertainties with summary of class notes - will post answers in answer folder.
Students did Spring Constant Lab - uncertainties not needed
Write-up: Name, Partners, Date, Lab Title
Data Table
Picture with calculations
Results: Discuss summary questions
Answer questions making sure to explain in answer what it is you are answering
Spring Constant Lab due on Thursday
Talked about Pumpkin Labs
Part 1: Emphasize Data Collection and Data Manipulation
Part 2: Emphasis on IB Planning (b) (Method), and Conclusions
Lectured on uncertainties:
1. If you have multiple measurements:
Find the average by: (M1 + M2 + ... + Mn)/n
Find the uncertainty by: (abs(M1-avg) + abs(M2-avg) + ... + abs(Mn-avg))/n
2. If you have one measurement of each quantity:
2a. Max Min method
Example of area of a rectangle
Max area = (L + uncL)*(W + uncW)
Min area = (L - uncL)*(W - uncW)
Avg area = (Max area + Min area)/ 2
Unc Area = (Max area - Min area)/ 2
2b. Method of Relative Uncertainty
This method cannot be used if the terms are added or subtracted but otherwise is powerful and easy to use
Used example of area of a rectangle
Area = L * W
Unc Area = A * (uncL/L + uncW/W)
If you have a complicated expression like: Z = (A^1/2) * (B^3)/(C^5)
you can use this method taking the absolute values of the exponents as coefficients in the relative uncertainty equation: uncZ = Z*((1/2)*uncA/A + 3*uncB/B + 5*uncC/C)
Handed out practice sheet on uncertainties with summary of class notes - will post answers in answer folder.
Students did Spring Constant Lab - uncertainties not needed
Write-up: Name, Partners, Date, Lab Title
Data Table
Picture with calculations
Results: Discuss summary questions
Answer questions making sure to explain in answer what it is you are answering
Spring Constant Lab due on Thursday
Talked about Pumpkin Labs
Part 1: Emphasize Data Collection and Data Manipulation
Part 2: Emphasis on IB Planning (b) (Method), and Conclusions
Monday, February 4, 2008
Friday, February 1, 2008
Friday, Feb 1, 2008
Went over problems from SHM worksheet.
Did some of the problems from AAPT practice test including problems in SHM, friction and coefficient of friction, conservation of energy, work.
Showed Parallel Axis Theorem for calculating Moment of Inertia (Rotational Inertia).
AAPT Physics Olympics Test will be given 3rd period on Monday, Feb 4.
I am giving points for completion (or good effort in completing) WebAssign assignments WA Hewitt Review ch. 2-4, and WA Hewitt Review ch 5-8. Current due date is Sunday, Feb 3, 2008.
Did some of the problems from AAPT practice test including problems in SHM, friction and coefficient of friction, conservation of energy, work.
Showed Parallel Axis Theorem for calculating Moment of Inertia (Rotational Inertia).
AAPT Physics Olympics Test will be given 3rd period on Monday, Feb 4.
I am giving points for completion (or good effort in completing) WebAssign assignments WA Hewitt Review ch. 2-4, and WA Hewitt Review ch 5-8. Current due date is Sunday, Feb 3, 2008.
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