Slide 1 / 106 Slide 2 / 106
Thermal Energy
www.njctl.org Slide 3 / 106
Temperature, Heat and Energy Transfer
· Temperature · Thermal Energy Click on the topic to go to that section · Energy Transfer · Specific Heat · Thermodynamics and Energy Conservation Slide 4 / 106
Temperature
Return to Table of Contents Slide 5 / 106
Sensing Temperature Which of the following do you think is colder, the ice cream orthe tea?
It is easy to tell if an object is hot or cold by touching it.
How hot or cold something feels is related to temperature, but only provides a rough indicator. Slide 6 / 106
What is Temperature? To understand temperature, rememberthat all matter is made of molecules that are in constant motion. What kind of energy do they have if they are in motion?
Even the molecules in this solid pencil are vibrating relative to a fixed position.
The water molecules in this glass are in constant random motion. Slide 7 / 106
Temperature and Kinetic Energy Temperature is directly proportional to the average kinetic energy of an object's molecules.
The more kinetic energy molecules have, the higher the temperature.
clip: Indiana University Slide 8 / 106
Thermal Expansion As the temperature of a substance increases, its molecules pick up speed and gain kinetic energy.
This increase in kinetic energy causes the molecules to spread farther apart and the substance expands.
image: National Oceanography Centre Slide 9 / 106
Thermal Contraction
As the temperature of a substance decreases, its molecules slow down and lose kinetic energy.
What do you think this decrease in kinetic energy causes?
Compare it to what we said about warm molecules. Slide 10 / 106
Thermal Expansion
Watch this demo of a metal ball and ring to see thermalexpansion.
Click here to watch a metal ball and ring demo.
Explain what happened to make the ballnot fit. How did the person make the ball fit again?
What is happening in terms of the kinetic energy of the molecules in the ball? Slide 11 / 106
Thermal Expansion
The change in volume a material experiences due totemperature changes depends on the type of material and the amount of temperature change.
Click here to watch what happens when things expand at different rates. Slide 12 / 106
1 All matter consists of molecules that are constantly in motion.
True
False Slide 12 (Answer) / 106
1 All matter consists of molecules that are constantly in motion.
True
False True Answer
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2 Temperature is the measure of the average ______of a substance's molecules.
A mass
B speed
C spacing
D kinetic energy Slide 13 (Answer) / 106
2 Temperature is the measure of the average ______of a substance's molecules.
A mass
B speed D. kinetic energy
C spacing Answer
D kinetic energy
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3 After a thunderstorm, the sun comes out and warms a puddle of water that is on the sidewalk. As the puddle of water gets warmer, its molecules: A speed up
B slow down
C take up less space
D gain kinetic energy Slide 14 (Answer) / 106
3 After a thunderstorm, the sun comes out and warms a puddle of water that is on the sidewalk. As the puddle of water gets warmer, its molecules: A speed up
B slow down A. speed up C take up less space D. gain kinetic energy Answer
D gain kinetic energy
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Measuring Temperature
Determining the kinetic energy associated with a substance's molecules would be difficult. Thermometers are used as a more practical way to measure an object's temperature.
A thermometer usually consists of a small amount of liquid, such as mercury or colored alcohol, in a narrow tube. Slide 16 / 106 Temperature Scales
Three scales of temperature commonly used are:
· Fahrenheit: used primarily in the United States
· Celsius: 1 degree Celsius= 3.2 degrees Fahrenheit
· Kelvin: is based on absolute zero, the lowest temperature something can have. Slide 17 / 106 Temperature Scales Slide 18 / 106 Slide 19 / 106 Slide 20 / 106 Temperature Conversions
The lowest temperature an object can have is the lowest value on the Kelvin scale 0 K! One Kelvin is equal to one degree on the Celsius scale. To convert from Celsius to Kelvin use the following equation. K= °C +273 Example: Water boils at 100°C. What is the boiling temperature of water in Kelvin?
Click the pot of boiling water for the answer! The answer is 373 K. Just add 273 to 100 °C!
Slide 21 / 106
4 The coldest temperature ever recorded was -89.2°C in Antarctica on July 21, 1983. Convert this temperature to °F. Slide 21 (Answer) / 106
4 The coldest temperature ever recorded was -89.2°C in Antarctica on July 21, 1983. Convert this temperature to °F.
-128.6 °F 184 K Answer
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5 The coldest temperature ever recorded was -89.2°C in Antarctica on July 21, 1983. Convert this temperature to Kelvin. Slide 22 (Answer) / 106
5 The coldest temperature ever recorded was -89.2°C in Antarctica on July 21, 1983. Convert this temperature to Kelvin.
-128.6 °F 184 K Answer
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6 If you measure the temperature of an object, its Kelvin temperature will be larger than its Celsius temperature. A never
B always
C sometimes
D not enough information to determine Slide 23 (Answer) / 106
6 If you measure the temperature of an object, its Kelvin temperature will be larger than its Celsius temperature. A never
B always B. always Answer C sometimes
D not enough information to determine [This object is a pull tab] Slide 24 / 106
7 The hottest recorded temperature ever recorded was about 329 K in Death Valley, California on July 10, 1913. What is this temperature in Celsius? Slide 24 (Answer) / 106
7 The hottest recorded temperature ever recorded was about 329 K in Death Valley, California on July 10, 1913. What is thisThis temperature is a more challenging in Celsius? question in that it requires students to come up with the "equation" for converting Kelvin to Celsius which is the reverse of converting Celsius to Kelvin. Have a student show their Answer work on the board or explain how they got the answer.
[This object56°C is a pull tab] Slide 25 / 106
8 The temperature in deep space is about 3 Kelvin. What is this temperature in °F ? Slide 25 (Answer) / 106
8 The temperature in deep space is about 3 Kelvin. What is this temperature in °F ?
about -454 °F Answer
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Thermal Energy
Return to Table of Contents Slide 27 / 106 Energy in Matter
Molecules in matter possess Kinetic Energy. Do you remember why molecules have kinetic energy?
Which drink is likely to have molecules with MORE kinetic energy?
How is kinetic energy related to an object's temperature? Slide 28 / 106
9 The hotter an object, the faster the molecules in it move. True
False Slide 28 (Answer) / 106
9 The hotter an object, the faster the molecules in it move. True
False TRUE Answer
[This object is a pull tab] Slide 29 / 106 Energy in Matter
Molecules in matter also possessPotential Energy. This energy is based on the attractive forces that all molecules exert on each other.
As the molecules move closer together, the potential energy associated with the molecules decreases.
As the molecules move farther apart, the potential energy associated with the molecules increases. Slide 30 / 106
10 What two types of energy do molecules in matter possess?
A Potential Energy
B Kinetic Energy
C Gravity
D Thermal Energy Slide 30 (Answer) / 106
10 What two types of energy do molecules in matter possess?
A Potential Energy
B Kinetic Energy A & B
C Gravity Answer
D Thermal Energy
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11 What type of energy describes the motion of molecules in matter?
A Kinetic Energy
B Potential Energy Slide 31 (Answer) / 106
11 What type of energy describes the motion of molecules in matter?
A Kinetic Energy
B Potential Energy Kinetic Energy Answer
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12 Potential energy found in matter is based on the ______between the molecules in matter. A energy
B attraction
C repulsion
D electrons Slide 32 (Answer) / 106
12 Potential energy found in matter is based on the ______between the molecules in matter. A energy B B attraction
C repulsion Answer
D electrons
[This object is a pull tab] Slide 33 / 106 Thermal Energy
The TOTAL kinetic and potential energy associated with ALL molecules in a substance is called thermal energy.
Kinetic Energy Potential Energy Thermal Energy
TOTAL molecular energy
Thermal energy and temperature areNOT the same because temperature only considers the average kinetic energy of molecules. Slide 34 / 106
Thermal Energy versus Temperature
Both containers of water below are measured to have the same temperature. However, one container of water has MORE thermal energy.
It has more water molecules!
Which has more thermal energy. Why? Click on the bucket for the answer. Slide 35 / 106
Energy Transfer
Return to Table of Contents Slide 36 / 106 Heat and Energy Transfer Heat is the transfer of thermal energy from a higher temperature object or location to a lower temperature object or location.
Why does the ice cream feel cold on the tongue?Thermal Click energy for transfersthe answer from the tongue to the ice cream.
WhyHeat does flows the from mug the of mug hot cocoato the hand.feel warm? Click for the answer. Slide 37 / 106 Heat
The amount of heat flow depends on the temperature difference between objects or locations.
Bigger temperature difference more HEAT
Lower temperature difference less HEAT
No temperature difference no heat (thermal equilibrium) Slide 38 / 106
13 Thermal energy and temperature describe the same thing. True
False Slide 38 (Answer) / 106
13 Thermal energy and temperature describe the same thing. True
False False Answer
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14 Heat is the transfer of thermal energy when there is temperature difference between objects or locations.
True
False Slide 39 (Answer) / 106
14 Heat is the transfer of thermal energy when there is temperature difference between objects or locations.
True
False True Answer
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15 Thermal energy moves from hotter objects or locations to colder objects or locations.
True
False Slide 40 (Answer) / 106
15 Thermal energy moves from hotter objects or locations to colder objects or locations.
True
False True Answer
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16 Which object will have the greatest heat exchange with a room that is at 20 degrees Celsius?
A ice cold water (at 6 degrees celsius)
B luke warm water
C room temperature water
D boiling water (at 100 degrees celsius) Slide 41 (Answer) / 106
16 Which object will have the greatest heat exchange with a room that is at 20 degrees Celsius?
A ice cold water (at 6 degrees celsius)
B luke warm water D boiling water because of the biggest difference in temperature C room temperatureAnswer waterwith the environment.
D boiling water (at 100 degrees celsius)
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Methods of Energy Transfer
Heat transfer can occur by:
· direct contact - Conduction
· electromagnetic waves -Radiation
· molecular movement - Convection Slide 43 / 106
Conduction
Heat transfer through direct contact is known asconduction .
The energy of faster moving molecules in the warmer finger transfers to the slower moving molecules of the colder ice by bumping into them.
This causes the molecules in the ice to move fasterand the molecules in the finger to move slower.
How does this relate to the temperature change the ice experiences? Slide 44 / 106
Conduction
Look at this Navy cook. Why is he using pot holders to carry the turkey?
Click here to watch conduction in action Slide 45 / 106 Conduction
Conduction occurs most easily in solids because their molecules are closer together.
Let's come up with some other examples of conduction below. Slide 46 / 106
17 Heat transfer by conduction involves direct physical ______.
A transfer
B movement
C contact
D fire Slide 46 (Answer) / 106
17 Heat transfer by conduction involves direct physical ______.
A transfer C B movement Answer C contact
D fire [This object is a pull tab] Slide 47 / 106
18 Conduction occurs most easily in ______because molecules are closer together.
A gases
B liquids
C solids
D all of the above Slide 47 (Answer) / 106
18 Conduction occurs most easily in ______because molecules are closer together.
A gases
B liquids C. solids Answer C solids
D all of the above [This object is a pull tab] Slide 48 / 106
19 Feeling the warmth of a campfire on your skin is an example of conduction.
True
False Slide 48 (Answer) / 106
19 Feeling the warmth of a campfire on your skin is an example of conduction.
True
False False, there is no direct physical contact. Answer
[This object is a pull tab] Slide 49 / 106
Radiation
Do you have to touch the sun to feel its warmth?
Of course not! The sun radiates energy in the form of electromagnetic waves. Click for the answer Molecules in your skin move faster after you absorb this energy causing your temperature to rise.
Heat transfer by electromagnetic waves through emptyspace or matter is known as radiation. Slide 50 / 106 Radiation
All objects radiate electromagnetic wave energy.
The hotter an object, the more energy it radiates.
Discuss why you think a person feels warmer in a room full of people than in a room by themselves. Slide 51 / 106
Radiation
Heat transfer through radiation does not involve the movement of matter.
Let's come up with some other examples of radiation below. Slide 52 / 106
20 Heat transfer by ______is called radiation.
A movement of matter
B sweating
C molecular motion
D electromagnetic waves Slide 52 (Answer) / 106
20 Heat transfer by ______is called radiation.
A movement of matter
B sweating D electromagnetic waves
C molecular motion Answer
D electromagnetic waves
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21 Radiation can not occur through empty space that has no matter.
True
False Slide 53 (Answer) / 106
21 Radiation can not occur through empty space that has no matter.
True
False False Answer
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22 Which of the following radiate energy in the form of electromagnetic waves?
A bowl of soup
B the sun
C a lake
D humans Slide 54 (Answer) / 106
22 Which of the following radiate energy in the form of electromagnetic waves?
A bowl of soup
B the sun All answers are correct Answer C a lake
D humans [This object is a pull tab] Slide 55 / 106
Convection
Heat transfer from one location to another by the movement of liquids or gases is known as convection.
Go through the next few slides to see an example of convection in a liquid. Slide 56 / 106
Convection
The burner conducts heat to the bottom of the pot. Slide 57 / 106
Convection
As the water heats up, its density decreases and it begins to rise to the top. Slide 58 / 106
Convection
Simultaneously, cooler and denser water at the top is displaced downward.
The displaced cooler water heats up at the bottom of the pot and the cycle continues creating a convection current. Slide 59 / 106
Convection
Natural convection also occurs in gases like the atmosphere.
Warm air
A sea breeze is an example Cool air of convection. Slide 60 / 106
Convection
Can you come up with any other examples of convection? Make a list with a partner. Slide 61 / 106
23 Convection occurs in______.
A solids
B liquids
C gases
D all of the above Slide 61 (Answer) / 106
23 Convection occurs in______.
A solids
B liquids B. liquids C. gases
C gases Answer
D all of the above
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24 A heater near the floor is turned on during the winter months to heat the room. Convection will occur.
True
False Slide 62 (Answer) / 106
24 A heater near the floor is turned on during the winter months to heat the room. Convection will occur.
True
False True Answer
[This object is a pull tab] Slide 63 / 106 Conductors versus Insulators
Materials that transfer heat easily through conduction are called conductors.
Insulators are materials that transfer heat poorly.
Insulator Why would the handle Conductor of a frying pan be made of a different material than the body? Slide 64 / 106 Conductors versus Insulators
Materials that are good conductors have atoms with "loose" electrons that can bump into other atoms and easily transfer thermal energy.
Metals like the base of this pan are good conductors.
Hot to the touch Cold to the touch
Good conductors are usually poor insulators.
Why is a metal frying pan cold to the touch when not in use, but hot when over a fire? Slide 65 / 106
Conductors
Materials that are good conductors have atoms with "loose" electrons that can bump into other atoms and easily transfer thermal energy.
aluminum
water Slide 66 / 106 Insulators
Insulators are usually porous materials with air spaces that act to reduce the transfer of heat. Good insulators are usually poor conductors.
glass
plastic
wood
air Slide 67 / 106
Conductors versus Insulators
A pizza baker's hands feel warm when in close proximity to the oven but will only burn if he accidentally touches the oven.
Air in and around the oven is a poor Whyconductor is this whereasthe case? the metal oven is an excellent conductor of heat.Click The hotterfor the oven explanation. will therefore transfer thermal energy to his cooler hand if he touches it. Slide 68 / 106
25 Conductors do not transfer heat easily while insulators do. True
False Slide 68 (Answer) / 106
25 Conductors do not transfer heat easily while insulators do. True
False False Answer
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26 Louisa wants to be able to hold a cup of hot cocoa while she waits for the bus. Which cup should she choose? A styrofoam cup
B aluminum cup
C glass cup
D plastic cup Slide 69 (Answer) / 106
26 Louisa wants to be able to hold a cup of hot cocoa while she waits for the bus. Which cup should she choose? A styrofoam cup All answers except aluminum which B aluminum cup is a metal are acceptable. The hot cocoa will heat the cup and she Answer C glass cup wants a cup that will not transfer the cup's thermal energy easily to her hand. D plastic cup [This object is a pull tab] Slide 70 / 106
Specific Heat
Return to Table of Contents Slide 71 / 106 Specific Heat
You reach for a slice of pizza fresh from the hot oven. You take a bite and the crust is nice and warm but when the sauce reaches your tongue it burns!
If the sauce and crust were at the same temperature, why do you think the sauce burned your tongue but the crust did not? Slide 72 / 106 Specific Heat The sauce transferred more thermal energy to your tongue raising your tongue's temperature.
TheBut sauce why did required the sauce more have thermal more energy thermal to energyreach the than same the crust?temperature Click asHERE the crust for the because answer. it had a higher specific heat capacity than the crust. Slide 73 / 106 Specific Heat
Specific heat describes the amount of energy in Joules (J) needed to raise the temperature of 1 kg of a substance by 1°C.
Different substances have different specific heat capacities. What do those values tell you about the substance?
table: electron9.phys.utk.edu Slide 74 / 106 Specific Heat
Differences in specific heat require different amounts of energy for the same change in temperature.
It takes about 800 Joules of energy to raise the 1kg temperature of 1 kg of rock by 1°C. Slide 75 / 106
Specific Heat
It takes about 1,700 Joules of energy to raise the temperature of 1 kg of wood by 1°C.
Which has the higher specific 1kg heat capacity, the rock or the wood? Slide 76 / 106 Specific Heat What happens if the same amount of thermal energy is transferred to substances of the same mass but different specific heats?
specific heat is in between For example, if equal temperature will be in between masses of water, sand and air each recieve 1000 Joules of energy how do their temperatures compare? highest specific heat lowest temperature Click the picture lowest specific heat for the answer. highest temperature Slide 77 / 106
27 Specific heat describes the energy needed to raise the temperature of 1kg of a substance by 1°C.
True
False Slide 77 (Answer) / 106
27 Specific heat describes the energy needed to raise the temperature of 1kg of a substance by 1°C.
True
False True Answer
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28 Which substance requires the least amount of energy to change its temperature by the same amount?
A 1 kg of ice
B 1 kg of lead
C 1 kg of water table: electron9.phys.utk.edu
D 1 kg of copper Slide 78 (Answer) / 106
28 Which substance requires the least amount of energy to change its temperature by the same amount?
A 1 kg of ice
B 1 kg of lead B 1 kg of lead table: electron9.phys.utk.edu
C 1 kg of Answer water It has the lowest specific heat. D 1 kg of copper
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29 Exactly 200 Joules of thermal energy are transferred to the following substances. Which undergoes the least amount of temperature change?
A 1 kg of water
B 1 kg of copper
C 1 kg of iron table: electron9.phys.utk.edu
D 1 kg of aluminum Slide 79 (Answer) / 106
29 Exactly 200 Joules of thermal energy are transferred to the following substances. Which undergoes the least amount of temperature change?
A 1 kg of water
B 1kg of water B 1 kg of copper Since it has the highest heat capacity, it requires a lot more C 1 kg of ironAnswer energy to change its temperature by table:the electron9.phys.utk.edu same amount. D 1 kg of aluminum
[This object is a pull tab] Slide 80 / 106 Specific Heat Identical substances with the same mass and the same specific heat will undergo different temperature changes if they recieve different amounts of thermal energy.
Use a red marker tool to illustrate on the thermometers the differences in water temperature between the two flasks of water. Slide 81 / 106 Specific Heat
Identical substances with different masses and the same specific heat will undergo different temperature changes if they recieve the same amount of thermal energy.
Use a red marker tool to illustrate on the thermometers the differences in temperature between the two rocks. Slide 82 / 106
30 Suppose two identical rocks of the same mass and same specific heat are heated differently. How could you Studentsdetermine type their answers which here rock received more thermal energy? Slide 82 (Answer) / 106
30 Suppose two identical rocks of the same mass and same specific heat are heated differently. How could you Studentsdetermine type their answers which here rock received more thermal energy?
Measure each rock's temperature. The rock with the higher temperature Answer had more thermal energy transferred to it.
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31 Suppose two identical rocks of different masses are heated. After they each receive 200 Joules of thermal energy. Rock "A" has a hotter temperature than rock "B". Which rock is more massive?
Rock A Rock B Slide 83 (Answer) / 106
31 Suppose two identical rocks of different masses are heated. After they each receive 200 Joules of thermal energy. Rock "A" has a hotter temperature than rock "B". Which rock is more massive?
Rock A Rock B is more massive. Rock B Answer
[This object is a pull tab] Slide 84 / 106 Temperature Changes
To summarize, the temperature changes a substance undergoes:
Are inversely proportional to the specific heat of the substance
higher specific heat smaller temperature change lower specific heat greater temperature change Slide 85 / 106 Temperature Changes
Are directly proportional to the amount of energy transferred to the substance.
More energy greater temperature change less energy smaller temperature change Slide 86 / 106 Temperature Changes
Are inversely proportional to the mass of the substance
1kg 2kg
more mass smaller temperature change
less mass greater temperature change Slide 87 / 106
32 What three quantities does the temperature change of an object depend on?
A the object's density
B the amount of energy transferred to it
C the object's mass
D the object's specific heat Slide 87 (Answer) / 106
32 What three quantities does the temperature change of an object depend on?
A the object's density
B the amount of energy transferred to it All except the object's density. C the object's mass Answer
D the object's specific heat
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33 100 Joules of thermal energy are added to the following objects. Which undergoes the greatest temperature change?
A 1 kg of aluminum
B 3 kg of aluminum table: electron9.phys.utk.edu C 1 kg of water
D 3 kg of water Slide 88 (Answer) / 106
33 100 Joules of thermal energy are added to the following objects. Which undergoes the greatest temperature change?
A 1 kg of aluminum
B 3 kg of aluminum A
Answer table: electron9.phys.utk.edu C 1 kg of water
D 3 kg of water [This object is a pull tab] Slide 89 / 106 Finding Temperature Change
Consistent with these relationships is the following equation for change in temperature.
Thermal energy specific heat capacity (Joules, J) (Joules/°C∙kg) TE ∆T = mc
mass change in (kilograms, kg) temperature (°C) Slide 90 / 106
Finding Temperature Change
Try using the equation for the following.
How much thermal energy must be added to 130 kg of bath water to change its temperature from 33°C to 37°C? The specific heat of water is 4186 J/°C∙kg. Slide 90 (Answer) / 106
Finding Temperature Change
Try using the equation for the following. TE= (m × c) × ∆T How much thermal energy must be added to 130 kg of bath water to change its = temperature (130kg × 4186 from J/°C∙kg) 33°C to × 37°C?4°C The specific heat of water is 4186 J/°C∙kg. Answer Don't forget, this is the change in temperature. (37°C-33°C= 4°C)
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34 A 0.03kg silver spoon with a specific heat of about 300 J/°C∙kg is placed into a cup of soup. The soup transfers 90 J of thermal energy to the spoon. What is the change in the spoon's temperature in °C? Slide 91 (Answer) / 106
34 A 0.03kg silver spoon with a specific heat of about 300 J/°C∙kg is placed into a cup of soup. The soup transfers 90 J of thermal energy to the spoon. What is the change in the spoon's temperature in °C?
10°C Answer
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35 You want to cool 0.35 kg of water from room temp 20°C to 5°C. How much thermal energy must be removed from the water? Water has a specific heat of 4186 J/°C∙kg. Slide 92 (Answer) / 106
35 You want to cool 0.35 kg of water from room temp 20°C to 5°C. How much thermal energy must be removed from the*Teacher water? Note: Water Use ofhas the aequation specific heat of 4186 J/°C∙kg. remains thesame despite the fact that we are removing thermal energy. Only the terminology has changed: "added" is now "removed" and the temperature of course is
Answer dropping instead of getting larger.
21, 977 J of thermal energy must be removed. [This object is a pull tab] Slide 93 / 106
36 A 0.20 kg aluminum baking pan is placed in an oven and absorbs 20,000J of thermal energy. If the baking pan had a starting temperature of 20°C, what is its temperature after being heated? The specific heat of aluminum is 900J/°C∙kg. Slide 93 (Answer) / 106
36 A 0.20 kg aluminum baking pan is placed in an oven and absorbs 20,000J of thermal energy. If the baking pan had a starting temperature of 20°C, what is its temperature after being heated? The specific heat of aluminum is 900J/°C∙kg.
131.1°C
If you use the equation to solve for ∆T, you get about 111.1°C. Since the pan started at 20°C then its final Answer temperature will be 20°Cplus 111.1°C.
[This object is a pull tab] Slide 94 / 106
Thermodynamics and Energy Conservation
Return to Table of Contents Slide 95 / 106 Slide 96 / 106 Slide 97 / 106
1st Law of Thermodynamics
The 1st law of thermodynamics is the law of conservation of energy.
Energy can not be created or destroyed, only converted from one form to another.
Work is done on the stick giving it kinetic energy. This kinetic energy is converted into heat energy. Slide 98 / 106 2nd Law of Thermodynamics
The 2nd law of thermodynamics states that heat normally flows from high temperature to low temperature.
Heat flow is from the warm coffee to the cooler environment.
Once the environment around the cup is warmer, the faster moving air molecules can not be forced to reheat the coffee. This is because all systems have a tendency to increase their disorder, or entropy. Slide 99 / 106
Heat Engine
Heat engines convert thermal energy into mechanical energy. Internal combustion engines in cars convert heat to mechanical energy through the following four-step process.
First drawing air and fuel vapor in. Next, the piston moves up and compresses the air-fuel mix. Fuel combusts and the air-fuel mix expands to pushes down on the piston, and the exhaust is driven out. Slide 100 / 106
37 The study of the relationship between heat and ______is called thermodynamics.
A thermal energy
B friction
C work
D conductors Slide 100 (Answer) / 106
37 The study of the relationship between heat and ______is called thermodynamics.
A thermal energy
B friction
C work work Answer D conductors
[This object is a pull tab] Slide 101 / 106
38 When work is done an object, there is a transfer of energy. True
False Slide 101 (Answer) / 106
38 When work is done an object, there is a transfer of energy. True
False
true Answer
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39 The 1st law of thermodynamics is basically a restatement of the law of conservation of ______.
A heat
B energy
C convection
D forces Slide 102 (Answer) / 106
39 The 1st law of thermodynamics is basically a restatement of the law of conservation of ______.
A heat B - energy
B energy Answer
C convection
[This object is a pull D forces tab] Slide 103 / 106
40 Which of the following are examples of the 1st law of thermodynamics? (pick more than one)
A you rub your hands together and they get warmer
B a chandelier hangs suspended from the ceiling
C the brakes cause a car's tires to skid on the road
D a person gets tired holding a tray above their head Slide 103 (Answer) / 106
40 Which of the following are examples of the 1st law of thermodynamics? (pick more than one)
A you rub your hands together and they get warmer
B a chandelier hangs suspendedA from and C the ceiling
C the brakes cause Answer a car's tires to skid on the road
D a person gets tired holding a tray above their head
[This object is a pull tab] Slide 104 / 106
41 The 2nd law of thermodynamics states that heat flows from colder objects to hotter objects.
True
False Slide 104 (Answer) / 106
41 The 2nd law of thermodynamics states that heat flows from colder objects to hotter objects.
True
False False Answer
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42 Entropy is the measure of order a system has. The more entropy a system has the more ordered it is.
True
False Slide 105 (Answer) / 106
42 Entropy is the measure of order a system has. The more entropy a system has the more ordered it is.
True
False False Answer
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43 Heat engines convert thermal energy (or heat) into ______energy.
A thermal
B mechanical
C potential
D convection Slide 106 (Answer) / 106
43 Heat engines convert thermal energy (or heat) into ______energy.
A thermal
B mechanical B - mechanical Answer C potential
D convection
[This object is a pull tab]