Slide 1 / 59 AP Physics 2 Thermal Physics Multiple Choice www.njctl.org Slide 2 / 59 1 Which of the following is NOT true when two systems with unequal temperatures come into contact with one another? A Heat will flow until thermal equilibrium is reached B No net heat flow occurs once thermal equilibrium is reached C Entropy is reduced during the process D The natural flow of heat will be from the warmer system to the colder system Slide 3 / 59 2 When one end of a cold metal spoon is placed upright in a cup of hot coffee, the other end eventually gets warmer. On the scale of the molecules of the spoon, which of the following is the primary explanation of this phenomenon? A Warmer molecules will rise to the top B The hot molecules produce thermal radiation that is then absorbed by the colder molecules. C Higher-energy molecules hit lower-energy molecules, increasing their speed and thus their temperature D Hotter areas have more molecules, which will flow upwards from areas of high concentration to low concentration
Slide 4 / 59 3 It is outside 20 ο C in Josh’s backyard. If her crabapple tree only blooms when the temperature is about 25 ο C, what will the temperature need to be in Fahrenheit before they bloom? A 71 ο F B 77 ο F C 85 ο F D 25 ο F Slide 5 / 59 4 Rose doesn’t feel well, but her mom will only let her stay home from school if she has a fever. She knows that she needs to have a temperature that is at least 99.5 ο F before she is allowed to stay home, but her thermometer works in Celsius instead of Fahrenheit. What temperature does the thermometer need to be? A 99.5 ο C B 27.5 ο C C 37.5 ο C D 38.5 ο C Slide 6 / 59 5 If systems 2 and 3 are both at thermal equilibrium with system 1, which of the following must be true? A Systems 2 and 3 are in thermal equilibrium with each other B System 2 has a higher temperature than system 3 C System 3 has a higher temperature than system 2 D Systems 2 and 3 are not in thermal equilibrium with each other
Slide 7 / 59 6 Assuming that the coefficient of linear expansion of a metal bar is is the same from 0°C to 50°C, which of the following temperature changes will produce the largest percent increase in the length of a metal bar? (select 2 answers). A An increase in temperature from 10° C to 14° C B An increase in temperature from 30° C to 31° C C An increase in temperature from 293 K to 297 K D A decrease in temperature from 48° C to 40° C Slide 8 / 59 7 A metal cup is left outdoors in the hot sun. As the cup’s temperature increases, which of the following statements about the inner and outer circumferences of the cup is true? A The outer circumference will not change, but the inner circumference will decrease. B The outer circumference will increase, but the inner circumference will not change. C The outer circumference will increase, but the inner circumference will decrease. D Both the outer and the inner circumferences will increase Slide 9 / 59 8 A bimetal plate consists of two materials of different coefficients of thermal expansion. The coefficient of thermal expansion of the top part of the plate is less than the bottom part. If the temperature of the entire plate increases, what happens to the plate? A Expands B Contracts C Stays the same D Bends up
Slide 10 / 59 9 A flat metal ring as shown increases in temperature over time. How will its shape change? (select 2 answers) A The inner radius will decrease B The outer radius will increase C The inner radius will increase D The outer radius will decrease Slide 11 / 59 10 At midnight, the temperature is 10 °C. At noon the next day, the temperature is 20°C. If a glass building was 413m tall at midnight, how many meters did it grow during the day? (The coefficient of linear thermal expansion for glass is approximately 8.5x10 -6 ( ο C) -1 ) A 413 m B 0.7 m C 0.035 m D 0.0011 m Slide 12 / 59 11 A solid copper ball with a mass of 50g and a temperature of 30 degrees Celsius is placed on a sheet of ice at 0 ο C, which then melts. If 50g of water at the same temperature were poured on the ice, would it melt the same amount of ice as the copper ball? A The water would melt more ice B The water would melt less ice C The water would melt the same amount of ice D Neither would melt any ice
Slide 13 / 59 12 Two metal bars are kept at the same temperature and are aligned with their nearer ends separated by a distance of 0.1m. Their far ends are clamped in place. One bar is made out of steel (α=10 -5 (C) -1 ). The other is made out of iron (α=1.2x10 -5 (C) -1 ). If the steel bar is initially 4 m long and the iron bar is initially 5 m long, how much must the temperature of the bars be changed to get them to touch? A 10 ο C B 100 ο C C 1000 ο C D 10000 ο C Slide 14 / 59 13 The specific heat of a liquid is 1000 J/(kg•K). How much heat is needed to raise the temperature of 2 kg of this liquid from 10 ο C to 20 ο C? A 2,000 J B 10,000 J C 20,000 J D 40,000 J Slide 15 / 59 14 Approximately how much heat must be removed from 0.5 kg of 50 °C water to freeze it into 0 °C ice? [for water Lf = 334,000 J/kg and c = 4200 J/(kg•K) ] A 105 J B 105,000 J C 167,000 J D 272,000 J
Slide 16 / 59 15 Which of the following is true about melting process? A The energy is required to increase the average kinetic energy of molecules B The energy is required to decrease the average kinetic energy of molecules C The energy is required to increase the potential energy between the molecules D No energy is required for this process it happens spontaneously Slide 17 / 59 16 A metal rod is placed so that it connects a heat source at 100°C and a heat sink at 10°C. During time t, an amount of heat Q is transferred from the source to the sink. if the metal rod is replaced by another made of the same material but of three times the length, how much heat will be transferred during the same amount of time t? A 1/9 Q B 1/3 Q C Q D 3 Q Slide 18 / 59 17 When we touch a piece of metal and a piece of wood that are placed in the same room, the piece of metal feels much colder than the piece of wood. This happens because of the difference in: A Specific heat B Temperature C Thermal conductivity D Latent heat
Slide 19 / 59 18 Given their coefficients of thermal conductivity, which of the following materials would best insulate a building? A Diamond (k= 2000 W/m•K) B Glass (k= 1 W/m•K) C Asbestos (k= 0.09 W/m•K) D Air (k=0.026 W/m•K) Slide 20 / 59 19 The state of an ideal gas was changed three times at three different temperatures. The diagram represents three different isothermal curves. Which of the following is true about the temperature of the gas? A T1 < T2 < T3 B T1 > T2 > T3 C T1 > T2 < T3 D T1 > T2 = T3 Slide 21 / 59 20 The state of an ideal gas was changed three times in a way that the pressure stays the same. The graph represents three isobaric lines. Which of the following is true about the pressure of the gas? A P1 > P2 > P3 B P1 > P2 < P3 C P1 < P2 < P3 D P1 = P2 > P3
Slide 22 / 59 21 Kinetic Theory is based on an ideal gas model. The following statements about the ideal gas are true EXCEPT: A All molecules move with the same speed B The average molecular kinetic energy is directly proportional to the absolute temperature C All molecules make elastic collisions with each other and the walls of the container D The attractive force between the molecules can be ignored Slide 23 / 59 22 Helium gas is sealed in a container. The container is heated, causing the temperature to increase at a constant rate. Which of the following statements is NOT true? A The pressure of the gas increases at a constant rate B Temperature of the gas increases at a constant rate C The average kinetic energy of the gas particles increases at a constant rate D The average speed of the gas particles increases at a constant rate Slide 24 / 59 23 A cylindrical container is sealed by a circular lid. The pressure in the room surrounding the container is 1.0 × 10 5 N/m 2 . The pressure inside the container is 0.3 × 10 5 N/m 2 . The lid has radius 0.10 m and weight 100 N. What is the minimum force required to lift the lid off of the container? A 3.15 × 10 3 N B 2.20 × 10 3 N C 2.30 × 10 3 N D 1.04 × 10 3 N
Slide 25 / 59 24 A gas with volume V, pressure P, and temperature T is trapped inside a cylindrical container with a moveable piston. If the temperature of a trapped gas is quadrupled while the volume is doubled, what will be the new pressure? A P B 1.5 P C 2 P D 3 P Slide 26 / 59 25 A cylindrical container of volume V holds 3 moles of Neon gas with pressure P and temperature T. If the gas is heated to a temperature of 2T and volume is kept constant, how many moles of gas are there in the container? A 3 moles B 1.5 moles C 1 mole D 0 moles Slide 27 / 59 26 A box contains a volume V of air with a pressure P and temperature T. If the box is never opened and no air can escape. If the temperature in the room is increased to 2T, what will be the new pressure in the box? A 1/2 P B P C 2 P D 4 P
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