Temperature and KE Classwork Name: _______________________________ Classwork #1 8 th Grade PSI Part I- Review how the molecules for a solid, liquid and gas differ at a constant temperature. 1. Follow this link: http://www.middleschoolchemistry.com/multimedia/chapter1/less on5 . Scroll down and click on the “Comparing Solids, Liquids and Gases” applet. Use the applet to describe the characteristics of each state in the following table. 2. Based on your table. Label whether each statement describes a Solid (S), Liquid (L) or Gas (G) There is a lot of free space between molecules as they are spread out all over the place. www.njctl.org 8th Grade PSI Thermal Energy State Attraction between molecules Movement between molecules Volume Shape Solid Liquid Gas
Transcript
Temperature and KE Classwork Name: _______________________________Classwork #1
8th Grade PSI
Part I- Review how the molecules for a solid, liquid and gas differ at a constant temperature. 1. Follow this link:
http://www.middleschoolchemistry.com/multimedia/chapter1/lesson5 . Scroll down and click on the “Comparing Solids, Liquids and Gases” applet. Use the applet to describe the characteristics of each state in the following table.
2.
Based on your table. Label whether each statement describes a Solid (S), Liquid (L) or Gas (G)
______ There is a lot of free space between molecules as they are spread out all
over the place.
______ It retains a fixed volume and shape.
______ Molecules are not attracted to each other much at all.
______ Molecules can move/slide past one another, yet still remain close
together due to their attraction to each other.
______ Molecules are strongly attracted to one another.
______ It has a definite volume but can change its shape to fit the container
that it is held in.
______ Particles stay in fixed positions and vibrate in place.
Part II- Describe how the motion of molecules in various states compare when substances are heated and cooled.
3. Let’s start by looking at a GAS. On the same webpage (http://www.middleschoolchemistry.com/multimedia/chapter1/lesson5), scroll down and click on “Heating Molecules of a Gas”. Use the applet to describe what happens to the balloon when the air inside is heated and cooled. Use pictures and words.
Go to http://www.middleschoolchemistry.com/multimedia/chapter1/lesson2 . Scroll down and click on “Heating and Cooling a Liquid”. Use the applet to describe what happens to the water molecules when heated in pictures and words.
Heated (word description) Heated (picture)
Cooled (word description) Cooled (picture)
Describe differences between what you saw in the liquid molecules compared to the gas molecules:
5. Go to http://www.middleschoolchemistry.com/multimedia/chapter1/lesson4 . Scroll down and click on “Heating and Cooling a Solid”. Use the applet to describe what happens to the solid particles when heated in pictures and words.
Describe how the motion of the solid molecules differs from the motion of the gas molecules (from #2) and the liquid molecules (from #3) when heated.
6. Circle the correct word or phrase in parentheses that will make the statement true.
a. The molecular motion will (increase, decrease) when a substance is heated.
b. The molecular motion will (increase, decrease) when a substance is cooled.
c. When a substance is cooled, the kinetic energy of its molecules will (increase,decrease).
d. The space between molecules gets (smaller, bigger) when a substance is heated.
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e. If the kinetic energy of a substance’s molecules decreases, then the substance is being (heated, cooled) and the space between molecules gets (smaller, bigger).
f. Though molecules in a solid and a liquid will both experience a(n) (increase,decrease) in kinetic energy when heated, the molecules in a (solid, liquid) will always be (closer to, further from) one another when compared to the molecules in a (solid, liquid) due to their strong attraction for one another.
Part III- Getting a “feel” for different temperature scales
7. Go to http://funphysics.jpl.nasa.gov/adventures/temperature-game.htmlRead the instructions and then start by clicking on “Fahrenheit”. When you get a match, fill in the temperature in Fahrenheit in the table below.
Once you’ve solved the puzzle, “close” the popup box. Click on Celsius and write down the corresponding temperatures in the table below. Do the same thing for Kelvin.
a. Which temperature scale gives the largest measurement for each icon?____________________________ The least?_______________________
b. What is the coldest item on your table?_______________________________________
c. What is the hottest item on your table?_______________________________________
8. On the same webpage, click on “More About Temperature” at the bottom. Read the popup text and answer the following.
a. Which scale of temperature is used primarily in the United States?b. Where is the Celsius temperature scale used?c. What temperature scale do scientists use?d. What is the international standard for scientific measurement of temperature?e. Define absolute zero:f. Define triple point:g. What is the triple point in Kelvins?h. Are divisions on the Kelvin scale referred to as “degrees”?i. How many divisions are there on the Celsius scale?j. What is the triple point in Celsius?k. How do you convert from Celsius to Kelvin?l. How do you convert from Kelvin to Celsius?m. At what temperature does water boil in Celsius? In Kelvins? In Fahrenheit?n. At what temperature does water at sea level freeze in Celsius? In Kelvins? In
Fahrenheit?o. Write down the equation for converting Fahrenheit to Celsius:p. Use the equation to convert 10°F to Celsius (show your mathematical work!). Use
the “automatic calculator” to check your answer:q. Write down the equation for converting Celsius to Fahrenheit:r. Use the equation to convert 27°C to Fahrenheit (show your mathematical work!).
Use the “automatic calculator” to check your answer.s. Convert 90° C to Kelvins (show your mathematical work!). Use the “automatic
calculator” to check your answer.
Temperature and KE Homework Name: __________________________Homework #1
8th Grade PSI
www.njctl.org 8th Grade PSI Thermal Energy
Fill in the blanks.1. ____________________________________________ is directly proportional to
the average kinetic energy of molecules in matter.2. If a substance is heated, its molecules __________________ up. Whereas if it is
cooled its molecules will ____________________ down.3. Hot water molecules have ________________ kinetic energy than cold water
molecules.4. Molecules in a solid ___________________ faster in position when heated.5. The spacing between molecules in matter ___________________ when the
matter is heated.6. Materials _________________________ when their temperatures increase and
______________________ when their temperatures decrease.7. The Celsius scale has _____________divisions. 8. On the Celsius scale, the freezing point is _____________ and the boiling point
is ____________.9. On the Fahrenheit scale, the freezing point is __________________ and the
boiling point is __________.10.The temperature scale that will always give the largest value when a substance’s
temperature is measured is _______________________.
Answer the following in complete sentences.11.Describe the differences in the attraction between molecules for a solid, liquid
and a gas.12.How will the motion of water molecules in hot soup differ from the motion of water
molecules in iced water?13. If a substance has a temperature of absolute zero, what can you say about the
kinetic energy of the substance’s particles?14.What are the differences between a thermometer that measures temperature on
the Kelvin scale and one that measures temperature on the Celsius scale?15.Describe how a thermometer uses thermal expansion/contraction to measure
temperature.16.Explain how the liquid level of an alcohol-based thermometer will be different
than the liquid level of a mercury based thermometer when heated. Why do the liquid levels differ?
Show your work for the following conversions.17.A person’s body temperature is measured at 38°C. Convert this temperature to
Fahrenheit. 18.The average temperature of a certain location is 286 Kelvin. Convert this
temperature to Celsius.19.A piece of dry ice has a temperature of -78°C. What is its temperature in
a. Kelvinb. Fahrenheit
20.Convert the following temperatures to the same temperature scale and order them from coldest to warmest: 180 Kelvin, 75°C ,45°F.
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Thermal Energy vs Temp Classwork Name: __________________________Classwork #2
8th Grade PSI
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Directions: For each pair of substances, state whether the kinetic energy (of molecules), potential energy (of molecules) and temperature for substance A is greater than (>), less than (<), or equal (=) to that for substance B. If there is not enough info to determine, state “can not be determined”. Provide justification for each of your answer.
1. A: 2g piece of ice at -1°C B: 2g piece of ice at -28° C
Kinetic Energy Temperature Potential Energy Thermal Energy
6. What does temperature indicate about the motion of molecules or particles in a substance?
7. How is potential energy related to molecules in matter?
8. Explain the difference between thermal energy and temperature.
Temp. and Thermal Energy Homework Name: ________________________Homework #2
8th Grade PSI
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Answer the following in complete sentences.1. What is the difference between temperature and thermal energy?2. How are temperature and thermal energy related?3. Suppose there are two cups holding the same amount of water except one cup
has hot water and the other has cold water. They have different temperatures, but how do they differ in the amount of thermal energy they possess?
4. Describe a scenario when two substances might have the same temperature, but not the same amount of thermal energy.
5. If hot pizza sauce touches your cooler tongue, in which direction does the heat flow? From your tongue to the sauce OR from the sauce to your tongue. Explain why.
6. In which case will there be more energy transferred as heat: a. 1 kg of water at 10°C in a freezer at -15°Cb. 1 kg of water at 60°C in an oven at 65°C
7. Why doesn’t thermal energy transfer between two substances with the same temperature?
8. Describe the difference between a conductor and an insulator in terms of thermal energy transfer and provide an example of each.
9. If you touch a metal spoon and then a wooden spoon that have the exact same temperature, which is going to feel warmer to the touch and why? Hint, your hand is warmer than both spoons.
10.Define the following methods of thermal energy transfer (heat):a. Conductionb. Convectionc. Radiation
11.How does radiation differ from conduction and radiation?12.Which method of thermal energy transfer occurs best in solids and why?13.Describe which methods of thermal energy transfer are involved when you sit by
a campfire roasting marshmallows.14.Which method of energy transfer would occur if two objects of differing
temperatures were placed in a vacuum but were not touching each other?
Methods of Thermal Energy Transfer Classwork Name: ____________________Classwork #3
8th Grade PSI
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Objective: Explore the three methods of heat transfer: conduction, radiation and convection using online simulations and be able to identify examples of each.
1. Go to http://www.teachersdomain.org/asset/lsps07_int_heattransfer/ .2. Read the introduction and then proceed to click on each type of heat transfer. For
each type of heat transfer, read the accompanying text and go through the animation to see an example in action. Don’t forget to also click and view the “Examples” tab. Complete the information in the attached table for each type of heat transfer as you go.
3. Apply heat transfer methods to cooking by going here http://www.scienceapplets.com/2012/10/summary-of-conduction-convection-and.html. Scroll down until you see the “Summary of Conduction, Convection and Radiation (with quiz)”. Click on the expand button on the bottom right hand
corner of the applet in order to expand the applet and take the quiz. Describe the three examples in the quiz:
Radiation-
Convection-
Conduction-
4. Test your knowledge by completing the activity here http://www.classzone.com/books/ml_science_share/vis_sim/mem05_pg119_heat/mem05_pg119_heat.html
Choose one example that you got incorrect on the first try and explain why it actually belongs in the heat transfer category it is in.
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Method of Heat Transfer
Description Describe the animation Other examples
Radiation
Conduction
Convection
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Thermal Energy Transfer Homework Name: _____________________________Homework #3
You have been learning about the three different ways that energy is transferred as heat: conduction, radiation, and convection. This thermal energy transfer only occurs for two substances or between two locations when there is a temperature difference. A mug of hot cocoa that is left sitting out in a room exhibits all three methods of thermal energy transfer: the cocoa loses heat by conduction through the cup’s sides (by direct contact with cooler molecules), the cup’s surface loses heat by radiation as electromagnetic waves are emitted and the air near the cup heats by convection as the air by the cocoa warms, rises, cools and then sinks creating a small convection current.
Directions: 1. For one day, document and describe examples of conduction, radiation and
convection that you directly observed throughout the day.2. Record your observations and descriptions on the attached sheets. 3. For each real life example, make sure to also identify which direction the heat
flowed. 4. You may supplement your work with diagrams and pictures.
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Con
duct
ion
Con
vect
ion
Rad
iatio
n
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Conductors vs Insulators Classwork Name: __________________________Classwork #4
8th Grade PSI
Objective: Use simulations to explore examples of conductors and insulators as they relate to thermal energy transfer.
1. Go to http://www.sciencekids.co.nz/gamesactivities/keepingwarm.html and scroll down until you see the simulation.
2. Insulate the beaker by choosing what you think is the best thermal insulator until you are correct.
3. Now you will complete an online experiment in which you determine how conductive (or how insulating) different materials are.
a. First, you are going to see how the liquid temperature changes with time when the beaker is not wrapped with material.
b. Click the start button. At 10 minutes hit pause. It’s okay if you can’t hit pause exactly at 10 minutes. Close to 10 minutes should be okay.
c. Remember the temperature of the liquid and then click on the “Table” button at the bottom to record this temperature in the table.
d. Go back to the simulation by clicking on the “Activity” button. e. Click the start button again. Hit pause at 20 minutes and record the
temperature again.f. Repeat this until you have a temperature reading for 0,10,20,30,40,50,an
60 minutes in your tableg. Click on the “Reset” button below and repeat the entire experiment but this
time cover the beaker with “Polystrene”. Next you will repeat the experiment with “Cardboard” and then “Metal Foil” so that your data table is complete. Note, you will have to click “Reset” before experimenting with each new material.
4. Click the button “Check” on the bottom to see if your data is correct. If you have any incorrect data, the box will be red and you should redo that part of the experiment to get the correct data.
5. Once your data is correct and completed, print it out or copy it on another sheet of paper.
6. Using your data, rank the three materials tested from most conductive (closer to the conductor end) to least conductive (closer to the insulators end).
7. Now, let’s check out some other materials. Go here http://www.scienceapplets.com/2012/06/conductors-and-insulators-game.html. Scroll down until you see the “Conductors and Insulators” Game and then click
on the expand button in the bottom right hand corner of the game box in order to expand and play the game. When you finish, the game, copy down the correct answers.
1. A 0.550 kg piece of copper is heated from 24°C to 45°C. How much thermal energy does the copper absorb?
2. A 2kg piece of iron is heated and gains 6,620J of thermal energy. What is the change in temperature of the piece of iron?
3. Determine the initial temperature of a 0.220 kg sample of tin when it is placed in a container of water. The water gains 3700J of energy and the final temperature of the tin is 19°C.
4. The specific heat of the human body is about 3300J/kg°C. How much thermal energy is required to raise your temperature by 2°C? Assume an average body mass of about 65kg.
5. A park bench made of iron has a mass of 135kg. On a warm day, its temperature changes from 25°C to 35°C. How much thermal energy does the bench absorb?
6. The water in a small pond radiates 1 x 1010J of thermal energy during the night. If the water’s temperature decreases by 5°C, what is the mass of the water in the pond? HINT: Use the specific heat equation to solve for (m x c) and then divide that answer by water’s specific heat capacity.
7. In order to cool a bowl of soup, you place several stainless steel spoons that have been stored in the freezer in the bowl of hot soup. As a result, the soup’s temperature changes from 82°C to 48°C. The mass of each spoon is 0.035kg and the mass of the soup in 0.15kg. How much thermal energy is removed from the soup? Since the soup is primarily made of water, use the specific heat of water when you solve this problem.
www.njctl.org 8th Grade PSI Thermal Energy
8. What is the initial temperature of a 0.755kg piece of iron that absorbs 40,679J of energy and if it’s final temperature is 403K?
9. A hot fluid is poured into a 0.40 kg drinking glass. 7,000J of thermal energy is transferred from the fluid to the glass increasing the glass temperature by 22°C. Determine the specific heat of the drinking glass. HINT: Use the specific heat equation to solve for (m x c) and then divide that answer by the mass of the drinking glass.
10.Water is cooled in a refrigerator by transferring 28,256 J of energy to the refrigerator environment. If the mass of water is 0.225 kg, by how much does the water change its temperature?
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Specific Heat Homework Name: _____________________________Homework #4
8th Grade PSI
Answer the following in complete sentences and/or show your mathematical work. Use the following specific heat table if necessary.
1. Define specific heat.2. What are the three variables that determine the amount of heat lost or gained
when a substance undergoes changes in temperature?3. Suppose you have 0.10kg of cooked apples on an aluminum pan with the same
mass. Both the apples and the aluminum pan have the same temperature. Which is most likely to burn your hand and why?
4. Why does the sand on a beach cool down more in the evening than the ocean water?
5. Which of the following two objects will provide the most thermal energy: 2kg of wood at 70°C or 2kg of bricks at 70°C? Explain.
6. a. What is the final temperature of 25kg of steam if it absorbs 800,000J of energy. The initial temperature of the steam was 393K.b. Repeat the above problem for 50kg of steam. Why is this answer different from that in part a?
7. a. How much thermal energy is transferred if a 100kg container of water changes its temperature from 25°C to 10°C.b. How much thermal energy needs to transfer in order to cool that same container of water from 25°C to 0°C? Why is this answer different from that in part a?
8. A sample of copper and a sample of gold are heated in the same oven. Both samples are identical in size and shape. After 10 minutes, which sample has the higher temperature? Explain.
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9. Your friend wants to see who can warm up a container a water over a campfire first. Both waters are the same starting temperature but you have twice as much water as your friend. Why does your friend have an advantage?
10.The temperature change of an object is:a. _________________________ proportional to the object’s specific heat.
b. _________________________ proportional to the amount of energy
transferred to or away from the object.
c. _________________________proportional to the object’s mass.
11.Define the following:a. Thermodynamicsb. 1st law of thermodynamicsc. 2nd law of thermodynamicsd. entropye. heat engines
12.Provide an example of the 1st law of thermodynamics.13.Draw a schematic diagram explaining how an internal combustion engine works.14.Choose ONE of the following examples of a heat engine and research how it
works online. Create a diagram of your chosen heat engine that explains how it works.
Refrigerator Heat Pump Air Conditioners Diesel Engine Steam Engine
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Hurricanes as Heat Engines Classwork Name: ___________________________Classwork #6
8th Grade PSI
Teacher notes: This activity is a pre-written activity by NASA where students see a real life application of heat engines as well as develop reading, data analysis and research skills. All instructions and links can be found here:
A brief summary of what students will do:1. Examine path of Hurricane Rita (Sept 18-24, 2005, Category 5 hurricane)2. Create daily data maps and time series plots of the sea surface temperature
(SST) for the Gulf of Mexico DURING and AFTER the passage of Hurricane Rita using a Live Access Server.
Temperature and KE CW #1 Answer Key1. Answers may vary slightly
2. G, S, G, L, S, G, L, S
3. Answers may vary slightlyHeated (word description)
Balloon expands
Heated (picture)
Cooled (word description)
Balloon shrinks
Cooled (picture)
This happens because when the molecules of the gas (air) are heated, they move faster, spread out and thus push out on the balloon. When the air is cooled, the molecules move slower, aren’t spread out and don’t push out on the balloon as much so it shrinks.
4. Answers may vary slightlyHeated (word description)
Molecules move faster and spread slightly apart
Heated (picture)
Cooled (word description) Cooled (picture)
www.njctl.org 8th Grade PSI Thermal Energy
State Attraction between
molecules
Movement between
molecules
Volume Shape
Solid
Very strong attraction
Molecules stay in fixed position but vibrate
Definite volume Definite shape
Liquid
Attracted, but less than solid molecules
Molecules can slip and flow past each other
Definite volume Takes on shape of container
Gas
Molecules are not attracted to each other much (the least of all 3 states)
Molecules can easily move past each other
No definite volume
No definite shape
Balloon shrinksMolecules don’t move as fast and are
therefore closer together. Liquid molecules, being more attracted to each other than gas molecules, do not spread out as much when heated.
5. Answers may vary slightlyHeated (word description)
Particles vibrate faster and move slightly apart
Heated (picture)
Cooled (word description)
Particles vibrate less and are closer together
Cooled (picture)
Solid molecules, being the most attracted to each other than either liquid or gas molecules, do not spread out nearly as much as gas/liquid molecules when heated. The molecules are not free to move and thus tend to vibrate more when heated rather than slip past each other.
6. a. increaseb. decreasec. decreased. biggere. cooled, smallerf. increase, solid, closer to, liquid
7. Icon Temperature
(Fahrenheit)Temperature (Celsius)
Temperature (Kelvin)
Saturn -229 -145 128
Death Valley 134 56 324
Freezing 32 0 273
Boiling Point 212 100 373
Space -454.54 -270 2.70
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Mars -81 -63 210
Antarctica -128 -89 183
Superfluid Helium
-455.76 -271 2.17
Room Temperature
68 20 293
Human Body 98.6 37 310
a. Kelvin, Fahrenheitb. Superfluid Heliumc. Boiling Point
8. a. Fahrenheitb. everywhere else but USc. Kelvinsd. Kelvin Scalee. absolute zero: the theoretical coldest temperature there could possibly bef. triple point: the point at which water co-exists as a solid, liquid and a gas in equilibriumg. 273.16 Kelvinh. noi. 100j. 0.01 °C k. add 273.15l. subtract 273.15m. 100°C, 373.15 Kelvin, 212°Fn. 0°C, 273.15 Kelvin, 32°Fo. C=5/9(F-32)p. -12.22 °Cq. F= (9/5C)x 32r. 80.6 °Fs. 363 Kelvin
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Temperature and KE HW #1Answer Key
1. temperature2. speed, slow3. more (or higher)4. vibrate5. increases6. expand, contract7. 1008. 0 degrees Celsisus, 100 degrees Celsius9. 32 degrees Fahrenheit, 212 degrees Fahrenheit10. Kelvins11. In a solid, molecules are the most attracted to each other which means
molecules are more or less in a fixed position. Molecular attraction in a liquid is less than that of a solid but more than that of a gas allowing molecules to slide and flow past each other. Gases have the weakest molecular attraction and gas molecules move easily and freely past each other.
12. Hot soup water molecules move faster than cold water.13. The kinetic energy of a substance with a temperature of absolute zero is
near zero. There is little to no motion.14. They differ by 273degrees. For example, 0 degrees Celsius corresponds to
273 Kelvin, the freezing point of water. 15. When the liquid inside a thermometer is heated, it will expand. Since the
liquid in a thermometer is encased in a narrow tube, the amount of expansion is easily visible and can be measured. The same principle works when the liquid inside the thermometer is cooled. In this case the liquid will contract and the liquid level will go down reflecting a decrease in temperature.
16. The alcohol level will be higher than the mercury level because the alcohol molecules are not as attracted to each other as the mercury molecules. When heated, this allows for the alcohol to experience more thermal expansion.
17. 100.4 degrees Fahrenheit18. 13 degrees Celsius19. a) 195 Kelvin b) -108.4 degrees Fahrenheit20. In degrees Celsius: -93, 75, 7.22 (in order -93, 7.22, 75)
In degrees Fahrenheit:-135.4, 167, 45 (in order -135.4, 45, 167)In Kelvins: 180, 348, 280 (in order 180, 280, 348)
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Thermal Energy versus Temperature CW #2Answer Key
1. A: 2g piece of ice at -1° C B: 2g piece of ice at -28°C
Kinetic Energy Temperature Potential Energy Thermal Energy>
Justification:Higher temp
>
Justification:Higher temp
=
Justification:Same state
>
Justification:KE is more, so TE is more
2. A: liquid water at 25 CB: liquid water at 77 F
Kinetic Energy Temperature Potential Energy Thermal Energy=
Justification:
They actually have the same temperature (have to convert)
=
Justification:
They actually have the same temperature (have to convert)
=
Justification:
Same temperature, same state.
Can not be determined
Justification:
Do not know how much liquid there is so do not know how much total molecular energy.
3. A: 8g of nitrogen gas at -150C B: 2g of nitrogen gas at -150C
Kinetic Energy Temperature Potential Energy Thermal Energy
=Justification:
Same temperature
=Justification:
Same temperature
=Justification:
Same temp, same
>Justification:
There are more
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state nitrogen gas molecules due to the larger mass so more total molecular energy.
4. A: 1g of liquid water at 25C B: 4g of liquid water at 30C
Kinetic Energy Temperature Potential Energy Thermal Energy
<Justification:Has a lower temperature
<Justification:Has a lower temperature
=Justification:Same state
<Justification:There is less liquid water in case “A” as well as less kinetic energy so there is less total molecular energy overall.
Summary questions:5. Define kinetic energy.
Energy of motion
6. What does temperature indicate about the motion of molecules or particles in a substance?
The higher the temperature, the faster the molecules and vice versa.
7. How is potential energy related to molecules in matter?
It is related to the attractive forces between molecules in matter. The further away molecules are from each other (i.e. close together in a solid), then the less potential energy there is.
8. Explain the difference between thermal energy and temperature.
Temperature is the average kinetic energy of molecules whereas thermal energy is the TOTAL molecular energy of a substance.
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Temperature and Thermal Energy HW #2Answer Key
1. Temperature is proportional to the average molecular kinetic energy. Thermal energy is the total molecular kinetic and potential energy.
2. Temperature and thermal energy are directly proportional IF the amount of substance in question is the same.
3. The hotter water will have more thermal energy because it has more kinetic energy (due to its higher temperature).
4. A big bowl of soup and a small cup of soup may have the exact same temperature or average molecular kinetic energy. But the bowl has more soup molecules overall, so it has more thermal energy than the small cup of soup.
5. Heat flows from the sauce to the tongue because heat flows from hot to cold and the sauce is hotter than the tongue.
6. Case ‘a’ will have more energy transfer because there is a larger temperature difference between the water and the environment.
7. Two objects at the same temperature do not exchange heat because they are in thermal equilibrium.
8. A conductor is a material that easily allows for thermal energy transfer while an insulator is a material that does not. An example of a conductor is aluminum while an example of an insulator is cloth.
9. The wooden spoon will feel warmer because it is not as good a conductor as the metal spoon. In fact wood is an insulator. This means, energy is transferred less efficiently from your hand to the wooden spoon compared to when you touch the metal spoon. This means your hand cools less efficiently when you touch the wooden spoon, so the metal spoon feels cooler.
10.a. Heat transfer through direct contactb. Heat transfer from the movement or circulation of fluids or gases of different temperature.c. Heat transfer via electromagnetic radiation.
11. It does not require a medium for thermal energy transfer.12.Conductors because molecules are closer together allowing thermal energy
to transfer from molecule to molecule easily.13.Radiation- from the warmth of the fire
Conduction- marshmallows touch the fireConvection- air above fire experiences convection currents (sparks)
14. Radiation
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Methods of Thermal Energy Transfer CW#3Answer Key2. answer key for table is attached3. Radiation- when the grill gets hot, it emits infrared radiation that travels through the air and is then absorbed by the bacon. Convection- water molecules near the bottom heat, rise, cool down at the top and then sink starting the cycle over and creating a convection current until all the water is heated. Conduction- As the pan heats, its molecules heat and start to vibrate. These vibrating molecules transfer their energy through the pan to the food. The food molecules in contact with the pan therefore start vibrating (heat up).
4.
Choose one example that you got incorrect on the first try and explain why it actually belongs in the heat transfer category it is in.Answers will vary
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Method of Heat Transfer
Description Describe the animation Other examples
Radiation
Answers may vary some: Transfer of energy along electromagnetic
waves When the wave comes into contact with an
object, the energy is transferred Radiation is the only heat transfer method
that can travel through empty space.
Electromagnetic waves from the sun travel through the air and reach the house. The house absorbs this thermal energy and the temperature inside the house increases.
Camp fire
Microwave oven
Light bulb
Human body
Conduction
Answers may vary some: Transfer of thermal energy between things
that are in direct physical contact Heat flows when molecules in one object
that are vibrating cause molecules in a neighboring object to vibrate
Works best in solids because particles are close together
Doesn’t work as well in liquids and less so in gases due to the spacing of particles
The molecules in the burner heat up and vibrate causing the molecules in the bottom of the pot to vibrate because they are touching. These vibrations (thermal energy) go through the entire pot. When the person reaches to touch it, the energy from the vibrations of the molecules in the pot handle are transferred to the molecules in the hand. Ouch!
Metals are good conductors (get hot and cold quickly because thermal energy propagates through them quickly)
Air and gases are not good conductors because thermal energy does not transfer easily from molecule to molecule as they are spaced apart.
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Convection
Answers may vary some: Transfer of heat by movement through a
medium such as air or liquid Primary heat transfer method for gases and
liquids When a gas or liquid is heated, the liquid
expands and rises because it is less dense. When the medium cools, it sinks because it
is denser. The cycling of a hot medium rising and a
cold medium sinking creates a convection current.
The stove is lit warming the air around in. This air rises because it less dense but then cools as it gets farther away from the stove. This cool air then sinks close to the stove where it is warmed again and rises creating a convection current.
Water boiling
Hot air balloon
A building (attic is warmer than a basement)
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Thermal Energy Transfer HW#3Answer KeyAnswers will vary from student to student.
Conductors versus Insulators CW#4Answer Key5.
6. Metal foil, cardboard, polystyrene7.
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Specific Heat CW#5Answer Key
1. 4446.75 J2. 7.37 °C3. 54 °C4. 4.29 x 105J5. 6.06 x 105J6. 4.78 x 105kg7. 21,349J8. 283K9. 795 J/kg °C10.30°C
Specific Heat HW#4Answer Key
1. The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree Celsius.
2. Mass, specific heat capacity, and the change in temperature3. The apples. Since the apples have a larger specific heat capacity, it
required more thermal energy to bring the apples to the same temperature as the aluminum. This larger amount of thermal energy will transfer to your hand if you touch it since your hand is cooler.
4. Sand has a lower specific heat than water. It gains more thermal energy during the day and loses more at night.
5. Wood because it has a higher specific heat than bricks.6. a. 410 Kelvin
b. 401 Kelvin. It is less because there is more mass to heat.7. a. 6.3 x 106J
b. 1.0 x 107J More thermal energy is required because the temperature change is greater.
8. Gold will have a higher temperature because it has a lower heat capacity meaning it requires less energy to change its temperature than copper.
9. Mass is inversely proportional to temperature change. More water yields a lower change in temperature.
10.a. inverselyb. directlyc. inversely
Thermodynamics HW#5Answer Key
1. a. the branch of science that studies how heat and work are relatedb. the law of conservation of energy- energy can not be created or destroyedc. heat flows from warmer to colder and all systems increase their disorderd. a measure of the amount of disorder in a systeme. something that converts heat to mechanical energy
www.njctl.org 8th Grade PSI Thermal Energy
2. Answers will vary3. Answers should reflect animated gif from SMART notebook slide 95: air
and fuel are drawn in, piston moves and compress air-fuel mix, fuel combusts and expands and pushes down on piston, exhaust is driven out.
4. Answers will vary. Sample outcome:
Image from http://researchthetopic.wikispaces.com/
Hurricanes as Heat Engines CW#6
Examples of output you should expect to see when your students do this activity.
Possible SST maps for DURING Rita
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www.njctl.org 8th Grade PSI Thermal Energy
www.njctl.org 8th Grade PSI Thermal Energy
www.njctl.org 8th Grade PSI Thermal Energy
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Possible SST maps for AFTER
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www.njctl.org 8th Grade PSI Thermal Energy
SST Time Series
Analysis Students should see that there is large drop in sea surface temperatures after the hurricane has passed. This is because the hurricane draws in warm moist ocean surface/air and uses it almost like fuel. This “fuel” is converted to heat energy in the thunderstorms that form around the hurricane eye. This heat refuels the hurricane. SSTs drop because the hurricane “uses” up the warm surface waters to fuel itself. Often, water from deeper in the ocean upwells to replace the surface waters.
