Introductory Physics, High School Learning Standards for a Full First-Year Course I. C O N T E N T S T A N D A R D S and radiation between objects or regions that are at different temperatures. 3.1 Explain how heat energy is transferred by convection, conduction, and radiation. 3.2 Explain how heat energy will move from a higher temperature to a lower temperature until equilibrium is reached. 3.3 Describe the relationship between average molecular kinetic energy and temperature. Recognize that energy is absorbed when a substance changes from a solid to a liquid to a gas, and that energy is released when a substance changes from a gas to a liquid to a solid. Explain the relationships among evaporation, condensation, cooling, and warming. 3.4 Explain the relationships among temperature changes in a substance, the amount of heat transferred, the amount (mass) of the substance, and the specific heat of the substance.
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 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 D. Heat is always transferred from the warmer object to the cooler object. Heat is transferred from the warm beaker to the cool water bath. C. The quantity of water doesn t change the freezing temperature. Freezing point is a physical characteristic of a substance. The freezing point of water is 0 C.
and radiation between objects or regions that are at different temperatures. 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? 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 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. 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. C. If the chocolate chips melted, heat must have been transferred to the chips since melting requires heat to be transferred to the substance. B. Two objects in thermal contact will experience heat transfer until thermal equilibrium is achieved. There is much more water than soda so the soda will experience a much larger temperature change, effectively cooling down until it has the same temperature as the water. (There is an energy transfer from the soda to the water for this to occur therefore some water molecules do gain energy.)
and radiation between objects or regions that are at different temperatures. 5.) If 1 kg of the compound toluene melts at 95 C, then 500 g of toluene will A. melt at 47.5 C. B. melt at 95 C. C. boil at 95 C. D. boil at 47.5 C. 6.) Which of the following is an example of heat transfer by conduction? 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 B. The quantity of toluene doesn t change the melting temperature. Melting point is a physical characteristic of a substance. The melting point of toluene is -95 C. A. Heat is transferred to the spoon from the soup and then within the spoon via conduction. Conduction is the mode of heat transfer within a solid.
7.) Four containers of water with different temperatures are placed on a table as shown below. The temperature of the room is 25 C. 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 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 A. Container W starts out with the temperature that is most different from the temperature of the room. Therefore, it must exchange the most heat with the environment in order to achieve thermal equilibrium with the room. A transfer of heat (directly proportional to the change in temperature) is necessary for a change in temperature to occur. B. Foam is an excellent insulator. It slows the rate of heat transfer due to the air trapped in the foam. Air is an extremely poor conductor of heat.
9.) If enough heat is taken away from a container of water, what will happen to the water? 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. 10.) In a copper wire, a temperature increase is the result of which of the following? 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 B. When heat is taken away from a liquid (water in this case), the liquid will cool until it reaches its freezing point. If one continues to take heat away from the liquid, the substance will freeze and become a solid. C. An increase in molecular motion causes an increase in temperature since temperature is a measure of the average molecular motion.
11.) The masses and specific heats of some samples of liquids are shown in the table below. Samples Mass (kg) Water.750 4200 Glycerin.750 2400 Methanol.750 2500 Cooking oil.750 2100 Specific Heat Capacity (J/kg*K) 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. The temperature of which sample will rise most when 1000 J of heat is added? A. water B. glycerin C. methanol D. cooking oil D. The cooking oil has the lowest specific heat capacity which means that it will experience the largest temperature change for a given transfer of heat. Low SHC means that it is easy to change the substance s 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. B. As the wire is bent, the molecules in the wire are moving more. When the molecules move more, the temperature rises since temperature is a measure of the motion of molecules. Therefore, the kinetic energy of motion is being transformed into heat.
13.) 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. 14.) The diagram below represents four empty copper containers at room temperature. 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 B. Warmer molecules are moving faster on average, so the warmer air will disperse the ammonia molecules more quickly. A. Container #1 is the smallest so it will experience a larger temperature change and the container will end up with a temperature closer to 90 C.
15.) Which of the following changes occurs as a solid is heated? 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. 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. 6.2 10 8 J B. 6.3 10 8 J C. 7.7 10 8 J D. 7.9 10 8 J D. As a substance is heated, the molecules experience an increase in speed. All of the other statements are false. A. Q mc T Q (1500kg)*(385J /kg K)*(1083 Ê C 15 Ê C ) Q 6.2X10 8 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 C. It takes a lot of heat to change the temperature of an object with a high SHC. Therefore, lots of heat would transfer from the block to the water. If the most heat transfers to the water, then the water experiences the largest change in temperature.
18.) The graph below represents changes in molecular motion in a solid plastic cylinder over time 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 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. C. An increase in temperature is caused by an increase in average KE of molecules. This is the definition of temperature. C. A substance with molecules with greater average speed has a higher temperature. This is the definition of temperature.
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. Which statement best accounts for these results? A. Iron is twice as dense as aluminum. B. Atoms of aluminum are smaller than atoms of iron. C. Using equal masses results in similar heat capacities. D. The specific heat of iron is less than that of aluminum. 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? A. The helium gas is more active in the winter season. B. Air outside the balloons leaks into the balloons. C. As the temperature increases, the helium in the balloons expands. D. Outdoor air pressure in the summer is less than indoor air pressure D. The relationship used to understand this question is Q=mc T. In this case Q and m are both the same for the two metals. If the relationship is rearranged, you see that c=q/(m T). Thus c and T are inversely related. A smaller specific heat capacity results in a larger change in temperature. C. The helium particles move much faster when they are warmer. When they move faster they also spread out more and thus the helium in the balloon expands.
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? B. Both the hot object and the water experience a change in temperature until they reach the same temperature, thermal equilibrium. Graph B is the only one that shows them reaching a common (and final) temperature.
23.) Which of the following figures correctly shows the conduction of heat within the system of metal blocks? A. Heat always flows from the warmer object to the cooler object. In this case heat flows from the 5 C block to the -20 C block and heat flows from the 100 C block to the 5 C.
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. a.) The water inside the kettle is boiling. Heat is transferred from the stove to the teakettle and then heat is transferred from the kettle to the water. The temperature of the water increases until it reaches its boiling point, 100 C. At 100 C the water begins to boil (vaporize). Water molecules that have enough energy change from the liquid phase to the gas phase. While boiling, the water stays constant at 100 C. The molecules are forming bubbles of water vapor beneath the surface of the water. The bubbles are buoyed up, rise up, and then the water vapor escapes. b.) The water vapor escapes the tea kettle and move through the air. The water vapor molecules strike the cold window and immediately transfer heat to the window. As the molecules give heat energy to the window, they lose enough heat to change back into liquid water and condense into liquid water droplets on the window.
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? a.) If the demonstration took place in a closed insulated beaker, the heat lost by the copper would be exactly equal to the heat gained by the water and the glass. In the open beaker, some heat could also be lost to the air and escape. b.) Water requires the most heat for a given change in temperature because it has the largest specific heat capacity. This is the definition of specific heat capacity. c.) The measured temperature is lower than they predicted because the demonstration is not taking place in a closed insulated beaker. Some heat is lost to the environment rather than being transferred to the water. d.) If.12kg of copper pipe were used, the final temperature would be greater. There would be more available heat energy for transfer if the pipe were twice as massive. This increased transfer of heat
energy would increase the final temperature of the water.
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. a.) Shortly after the hot plate is turned on, the average motion of the water molecules at point A is much faster than the average motion of the water molecules at point B. Heat is being transferred by conduction from the hot plate to the container and from the container to the water. The water molecules closest to the hot plate will be affected first. And as heat energy is transferred, molecules move faster on average. b.) The average motion of the water molecules at points A and B would now be the same. If the temperature is 100 C, and there is still water in the container, then all of the water is 100 C. The water stays at 100 C while the water boils and until all of the water becomes water vapor. c.) After several hours the water molecules will have cooled down to room temperature. At this time, all of
the molecules will on average have the same motion since they will have the same temperature.