Slide 1 / 67 Slide 2 / 67 8th Grade Thermal Energy Study Guide 2015-10-09 www.njctl.org Slide 3 / 67 Thermal Energy Study Guide www.njctl.org
Slide 4 / 67 Part 1 Define the following terms and/or concepts 1 Temperature Slide 5 / 67 2 Kinetic Energy Slide 6 / 67
3 Thermal expansion Slide 7 / 67 4 Thermal contraction Slide 8 / 67 5 Potential Energy (between molecules) Slide 9 / 67
6 Thermal Energy Slide 10 / 67 7 Heat Slide 11 / 67 8 Thermal Equilibrium Slide 12 / 67
9 Conduction Slide 13 / 67 10 Radiation Slide 14 / 67 11 Convection Slide 15 / 67
12 Conductors Slide 16 / 67 13 Insulators Slide 17 / 67 14 Specific heat Slide 18 / 67
15 Thermodynamics Slide 19 / 67 16 Work Slide 20 / 67 17 1st law of thermodynamics Slide 21 / 67
18 2nd law of thermodynamics Slide 22 / 67 19 entropy Slide 23 / 67 20 heat engine Slide 24 / 67
Slide 25 / 67 Part 2 Directions: Select the answer choice that best completes the statement or answers the question. 21 When a liquid is cooled, the liquid molecules Slide 26 / 67 A spread farther apart. B move slower than before. C experience thermal contraction. D increase their kinetic energy. 22 This type of heat transfer can occur in outer space. Slide 27 / 67 A Conduction B Convection C Radiation D Entropy
23 An insulator is a material that has molecules that Slide 28 / 67 A are closely packed together. B move easily past one another. C do not transfer heat easily. D will shrink when heated. 24 The following objects are all heated from 10 C to 30 C. Which object will transfer the most energy to your hand? Slide 29 / 67 A 5kg apples B 2kg apples C 5kg gold D 2kg gold 25 Two objects of the same material but different masses are subjected to the same thermal energy input. Slide 30 / 67 A The object with less mass will experience a greater change in temperature. B The object with more mass will experience a greater change in temperature. C They will both experience the same change in temperature. D It is impossible to compare their changes in temperature without knowing the specific heat of the objects.
26 All of the following are examples of conductors except Slide 31 / 67 A Silver B Water C Air D Aluminum 27 A 80 C object and a 60 C object sit (not touching) in a 21 C environment. Which best explains what will happen. Slide 32 / 67 A Both objects will get warmer. B The warmer object will exchange heat with the environment at a slower rate. C The environment will get warmer. D The warmer object will cool down while the cooler object will stay the same temperature. 28 An example of heat transfer by convection is Slide 33 / 67 A touching a hot pan and burning your finger B water boiling in a pot on the stove C feeling the warmth of a campfire on your face D the sun warming the roof of a house
29 Which of the following is an example of energy conservation? Slide 34 / 67 A An apple hangs suspended from a tree. B A person stands on tiptoes. C A car waits at a red light. D A hockey puck slides to a stop due to friction. 30 When energy is transferred as heat, the amount of useable energy Slide 35 / 67 A decreases. B remains the same. C increases. D is always zero. Slide 36 / 67 Part 3 Directions: Answer the following thoroughly. A table of specific heats is attached.
Slide 37 / 67 Substance Specific Heat (J/kg C) Aluminum 897 Apples 3,300 Bricks 800 Carbon 709 Copper 385 Gold 129 Iron 449 Mercury 140 Steam 1,870 Tin 230 Water 4,186 Wood 1,700 31 How are temperature and kinetic energy related? Slide 38 / 67 32 Describe what happens to motion and spacing of molecules when heated or cooled for a: Slide 39 / 67 A liquid B solid C gas
33 What does a thermometer measure? Slide 40 / 67 34 Describe characteristics of the three temperature scales including freezing and boiling point of water for each. Slide 41 / 67 35 Complete the following conversions: Slide 42 / 67 A 37 C to Fahrenheit B 384 Kelvin to degrees Celsius C -45 C to Kelvin D 45 F to degrees Celsius
36 Using the ideas of thermal expansion and contraction, describe how a liquid thermometer works. Slide 43 / 67 37 Recall the video shown in class of the bimetallic strip that was bent when it was heated. Explain why it bent. (HINT: remember that the strip was made of two different metals) Slide 44 / 67 38 When does potential energy between molecules increase? Decrease? Slide 45 / 67
39 What two types of energy do molecules possess? Slide 46 / 67 40 Explain why thermal energy and temperature, though related, are different. Slide 47 / 67 41 Provide an example of when two substances might have the same temperature but different thermal energy. Slide 48 / 67
42 Which will cool fastest initially in a room temperature room? Boiling water or lukewarm water? Slide 49 / 67 43 How are heat flow and temperature differences related? Slide 50 / 67 44 Will heat flow between two objects touching that have the same temperature? Why or why not? Slide 51 / 67
45 Which direction does heat flow? Give an example. Slide 52 / 67 46 What are the three methods of thermal energy transfer? Give a couple of examples of each. Slide 53 / 67 47 Do all objects emit the same amount of radiation? Why or why not? Slide 54 / 67
48 Conduction occurs primarily in solids. Why? Slide 55 / 67 49 What is the primary difference between conductors and insulators? Slide 56 / 67 50 Give several examples of conductors and insulators. Slide 57 / 67
51 If you wanted water to boil quickly in a tea kettle, what kind of material would you use for the tea kettle? Slide 58 / 67 52 If you wanted to maximize heat transfer, what kind of material would you use? How about if you wanted to minimize heat transfer? Slide 59 / 67 53 If you have several spoons made of conducting materials and insulating materials, which will feel cooler to the touch and why? Slide 60 / 67
54 Suppose you took a bite of pie that was at a certain temperature. The crust doesn t burn you but the filling does. Using the idea of specific heat, explain why the filling burned you but the crust didn t even though they had the same temperature. Slide 61 / 67 55 State whether the variable is inversely or directly proportional to the temperature change. Provide an illustrative example for each. Slide 62 / 67 A mass B specific heat C thermal energy transferred 56 Calculate the heat input (or output) required to change the temperature of 3kg of iron by 3 degrees Celsius. Slide 63 / 67
57 Calculate the final temperature of 0.020 kg of mercury that loses 500J of thermal energy and started with a temperature of 400Kelvin. Slide 64 / 67 58 Calculate the change in temperature of 10kg of wood that gains 3,000J of thermal energy. Slide 65 / 67 59 Give an example of the 1st law of thermodynamics in action. Slide 66 / 67
60 What energy conversions are involved in a heat engine? Slide 67 / 67