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AHS Introductory Physics MCAS Review Packet #3: Heat and Thermal Energy 1.) A student in a laboratory transfers a beaker containing a hot solution from the lab table to a cool water bath. Which of the following parts of the system experiences an increase in heat energy? A. beaker B. lab table C. solution D. water bath 3.) On a hot day, Jenny walked home from the grocery store with a bag of chocolate chips. When she arrived home the chocolate chips had melted in the bag. Why did the chocolate chips melt? 2.) A container is filled with 100 mL of water and placed in a freezer. The water in the container freezes at 0°C. A second container filled with 90 mL of water is placed in a second freezer. At what temperature does this second container of water freeze? A. -10°C B. 1°C C. 0°C D. 10°C 4.) A flowing stream contains water at 18ºC. Cans of soft drinks at 28ºC are lowered into the stream. Which of the following will most likely occur? A. Heat transferred from the chocolate chips to the bag. B. Heat evaporated from the bag to the chocolate chips. C. Heat transferred from the environment to the chocolate chips. D. Heat condensed from her hand to the Chocolate chips A. The soft drink cans will absorb cold energy from the stream’s water. B. The cans will cool until their temperature is the same as the stream’s. C. The temperature of the soft drinks will not change since the cans are sealed. D. The temperature of the cans will decrease to freezing as long as the stream is flowing. 5.) If 1 kg of the compound toluene melts at –95°C, then 500 g of toluene will 6.) Which of the following is an example of heat transfer by conduction? A. melt at –47.5°C. B. melt at –95°C. C. boil at 95°C. D. boil at 47.5°C. A. a whole metal spoon getting hot when one end is in hot soup B. the inside of a car in the sun getting very hot C. a tar road getting hotter in the sun than a concrete sidewalk D. a fireplace fire heating a room on a cold day 7.) Four containers of water with different temperatures are placed on a table as shown below. The temperature of the room is 25°C. 8.) In Colonial America, people used ice to help keep foods fresh. They cut the ice from lakes and ponds during the winter and stored the ice in icehouses. They sometimes used hay as an insulator to prevent the ice from melting. If you wanted to build an icehouse today, which of the following would be the best material to use as an insulator? A. dried leaves B. foam blocks C. plastic wrap D. rock salt After four hours, which beaker of water will have exchanged the most heat energy with the environment? A. W B. X C. Y D. Z 9.) If enough heat is taken away from a container of water, what will happen to the water? 10.) In a copper wire, a temperature increase is the result of which of the following? A. It will begin to boil. B. It will become a solid. C. It will turn into a gas. D. It will increase in weight. A. an increase in the size of the copper particles B. a decrease in the mass of the copper particles C. an increase in the motion of the copper particles D. a decrease in the distance between the copper particles 2 11.) The masses and specific heats of some samples of liquids are shown in the table below. Samples Mass Specific Heat (kg) Capacity (J/kg*K) Water .750 4200 Glycerin .750 2400 Methanol .750 2500 Cooking oil .750 2100 The temperature of which sample will rise most when 1000 J of heat is added? A. water B. glycerin C. methanol D. cooking oil 12.) The illustration below shows a student bending a piece of wire back and forth at a single point X. The wire’s temperature rises noticeably at point X. 13.) Perfume sprayed from a bottle spreads more easily in a warm room of 25°C than in a cool room of 15°C. Which of the following correctly compares perfume molecules at 25°C to those at 15°C? 14.) The diagram below represents four empty copper containers at room temperature. Which of the following best describes the source of the temperature increase? A. Some of the wire’s mass is transformed into heat energy as the wire is bent. B. Some of the kinetic energy is transformed into heat as the wire is bent. C. The bending transfers potential energy to the wire, heating it. D. The bending causes a current that heats the wire. A. At 25°C, they have more mass. B. At 25°C, they are moving faster. C. At 25°C, they have less kinetic energy. D. At 25°C, they are decreasing in volume. An equal amount of water at 90°C is added to each copper container. Assume there is no loss of heat to the environment. Which container will have had the greatest change in temperature when the water and the container reach equilibrium? A. 1 B. 2 C. 3 D. 4 3 15.) Which of the following changes occurs as a solid is heated? 16.) A recycling plant manager needs to melt 1500 kg of scrap copper to sell to a wire manufacturer. The copper is at 15°C and its melting point is 1083°C. The copper has a specific heat of 385 J/kg • K. How much heat is required to raise the temperature of the copper to its melting point? A. The kinetic energy of the solid decreases. B. The average density of the solid increases. C. The specific heat capacity of the solid decreases. D. The average molecular speed in the solid increases. A. 6.2 • 108 J B. 6.3 • 108 J C. 7.7 • 108 J D. 7.9 • 108 J 17.) The instructions below outline the procedure for a demonstration. Materials: four 100 g metal blocks, each of a different metal, four polystyrene foam cups, each containing 150 g of 10°C water Procedure: 1. Place the four cups of water next to each other on the lab bench. 2. Heat each block to a temperature of 60°C. 3. Place each heated block in a separate cup of 10°C water. 4. Measure the temperature change in each cup of water after 100 s. At the end of the demonstration, which block raised the temperature of the 10°C water the greatest amount? A. the block with the greatest density B. the block with the lowest surface area C. the block with the greatest specific heat D. the block with the lowest thermal conductivity 4 18.) The graph below represents changes in molecular motion in a solid plastic cylinder over time 19.) Two boxes, A and B, both contain the same number of nitrogen gas molecules. The gas molecules in box A have twice the average speed of the molecules in box B. Which of the following best describes the nitrogen gas in box A? A. The nitrogen gas in box A has a greater mass than the nitrogen gas in box B. B. The nitrogen gas in box A has a greater density than the nitrogen gas in box B. C. The nitrogen gas in box A has a greater temperature than the nitrogen gas in box B. D. The nitrogen gas in box A has a greater specific gravity than the nitrogen gas in box B. These changes in the molecules of the plastic cylinder must be accompanied by which of the following? A. an increase in mass B. a decrease in volume C. an increase in temperature D. a decrease in heat capacity 20.) A 10 g sample of aluminum and a 10 g sample of iron were each heated by 100 joules of energy. The temperature of the aluminum sample rose 11˚C, while the temperature of the iron sample increased 23˚C. 21.) A party shop delivers helium-filled balloons to homes and businesses. The owners realize from experience that on hot summer days they should inflate the balloons only three-quarters full. On cold winter days they can fully inflate the balloons. Which of the following is the best hypothesis to explain this observation? Which statement best accounts for these results? A. The helium gas is more active in the A. Iron is twice as dense as aluminum. winter season. B. Atoms of aluminum are smaller than B. Air outside the balloons leaks into the atoms of iron. balloons. C. Using equal masses results in similar heat C. As the temperature increases, the helium capacities. in the balloons expands. D. The specific heat of iron is less than that D. Outdoor air pressure in the summer is of aluminum. less than indoor air pressure 5 22.) The illustration below represents an experiment in which a hot object is added to a container of water at room temperature. The water is continuously stirred while the hot object is immersed in it. Which of the following graphs best shows the temperature changes that follow? 6 23.) Which of the following figures correctly shows the conduction of heat within the system of metal blocks? 7 24. Measurements inside a sealed container show that the pressure exerted by a gas increases as the thermal energy of the gas increases. 25. A heated rock is placed in a container of water that is cooler than room temperature. Which of the following statements best describes what happens? Which of the following best explains this pressure increase? A. Cold is removed from the container of water until the rock, the container, and the water all reach the same final temperature. A. The gas molecules stick to the walls of the container. B. The heated rock loses heat to the container of water until the rock, the container, and the water all reach the same final temperature. B. The gas molecules radiate energy in the form of nuclear particles. C. The gas molecules begin to bond together into heavier molecules. C. The heated rock loses heat to the container of water until the rock, the container, and the water each reach a different final temperature. D. The gas molecules move faster and strike the container walls more frequently. D. Cold is removed from the container of water until the rock, the container, and the water each reach a final temperature lower than their original temperatures. 26. A window washer noticed that, from the same distance and with no breeze, the smell of ammonia glass cleaner reached him faster on a hot day (30°C) than on a cold day (5°C). Which of the following explains this observation? A. Molecules expand at higher temperatures. B. Molecules move more rapidly at higher temperatures. C. The convection currents carry molecules at higher temperatures. D. The chemical reaction of molecules increases at higher temperatures. 8 27. A student hypothesizes that the mass of a substance affects how the temperature of the substance changes when it is heated. The student uses the following procedure to test the hypothesis. • Each sample is initially at room temperature before heating. • Each sample is heated for the same amount of time with the same heat source. • The final temperature is measured for each sample. Which of the following would be the best way to select the samples for testing the student’s hypothesis? A. Obtain samples of one substance, each with the same mass. B. Obtain samples of one substance, each with a different mass. C. Obtain samples of different substances, each with the same mass. D. Obtain samples of different substances, each with a different mass. Practice: Open-response question #1 BE SURE TO ANSWER AND LABEL ALL PARTS OF THE QUESTION. Show all your work (diagrams, tables, or computations) If you do the work in your head, explain in writing how you did the work. A cook notices a teakettle full of water on a stove. There is a cold window close to the spout of the kettle. The water begins to boil and water droplets begin to form on the window. a. Describe in detail what is happening to the water inside the kettle. b. Why do the water droplets form on the window? Be sure to explain in detail. 9 Practice: Open-response Question #2 BE SURE TO ANSWER AND LABEL ALL PARTS OF THE QUESTION. Show all your work (diagrams, tables, or computations) If you do the work in your head, explain in writing how you did the work. 1. The table below shows initial data from a laboratory demonstration. In the demonstration, a heated 0.06 kg copper pipe was dropped into a beaker of water. Students in the class were asked to predict the final temperature of the beaker of water when it reached equilibrium with the copper pipe. a. If this demonstration took place in a closed insulated beaker, instead of in an open beaker, what would be the relationship between the heat lost by the copper and the heat gained by the water and glass? b. Which material in the table above requires the most heat for a given change in temperature? c. The students found that the measured temperature was lower than they predicted. How would the students best explain this difference from the predicted temperature? d. Assume a heated 0.12 kg copper pipe was used instead of the given pipe. How would this change affect the final temperatures of the water and of the glass beaker? 10 Practice: Open-response Question #3 BE SURE TO ANSWER AND LABEL ALL PARTS OF THE QUESTION. Show all your work (diagrams, tables, or computations) If you do the work in your head, explain in writing how you did the work. The illustration below shows a container of water on an electric hot plate. Point A is in the water close to the hot plate, and point B is in the water near the top of the container. The water in the container is at room temperature before the hot plate is turned on. a. Describe the differences in the average motion of the water molecules at point A and at point B shortly after the hot plate is turned on. b. The water is heated until a thermometer placed in the center of the container reaches 100°C. Compare the average motion of the water molecules at points A and B at this temperature and explain your answer. c. The hot plate is then turned off. Describe the average motion of the molecules at points A and B after several hours. 11 Practice: Open-response Question #4 BE SURE TO ANSWER AND LABEL ALL PARTS OF THE QUESTION. Show all your work (diagrams, tables, or computations) If you do the work in your head, explain in writing how you did the work. In an experiment, liquid 1 is at room temperature (21°C) and liquid 2 has been heated until it is warmer than room temperature. A student takes equal amounts of liquid 1 and liquid 2 and mixes them together in a beaker. a. Compare the initial temperatures of liquid 1 and liquid 2 with the temperature of the mixture in the beaker at each of the following times: • 5 minutes after mixing • 2 hours after mixing b. Describe the transfer of heat energy between the two liquids in the beaker. c. Identify one other possible heat energy transfer in this experiment. 12