1. Which is the largest unit: one Celsius degree, one Kelvin degree, or one Fahrenheit degree? 1) one Celsius degree 2) one Kelvin degree 3) one Fahrenheit degree 4) both one Celsius degree and one Kelvin degree 5) both one Fahrenheit degree and one Celsius degree 13.1Degrees 13.1Degrees

2. Which is the largest unit: one Celsius degree, one Kelvin degree, or one Fahrenheit degree? 1) one Celsius degree 2) one Kelvin degree 3) one Fahrenheit degree 4) both one Celsius degree and one Kelvin degree 5) both one Fahrenheit degree and one Celsius degree The Celsius degree and the Kelvin degree are the same size. The scales only differ by an offset, not by the size of the degree unit. For Fahrenheit, there are 180 degrees between boiling and freezing (212°F–32°F). For Celsius, there are 100 degrees between the same points, so the Celsius (and Kelvin) degrees must be larger. 13.1Degrees 13.1Degrees

3. It turns out that – 40°C is the same temperature as – 40°F. Is there a temperature at which the Kelvin and Celsius scales agree? 1) yes, at 0 °C 2) yes, at -273 °C 3) yes, at 0 K 4) no 13.2Freezing Cold 13.2Freezing Cold

4. It turns out that – 40°C is the same temperature as – 40°F. Is there a temperature at which the Kelvin and Celsius scales agree? 1) yes, at 0 °C 2) yes, at -273 °C 3) yes, at 0 K 4) no The Celsius and Kelvin scales differ only by an offset, which is 273 degrees. Therefore, a temperature on one scale can never match the same numerical value on the other scale. The reason that such agreement is possible for Celsius and Fahrenheit is the fact that the actual degree units have different sizes (recall the previous question). 13.2Freezing Cold 13.2Freezing Cold

5. 13.4Glasses 13.4Glasses 1) run hot water over them both 2) put hot water in the inner one 3) run hot water over the outer one 4) run cold water over them both 5) break the glasses Two drinking glasses are stuck, one inside the other. How would you get them unstuck?

6. outer glass outer one to expand Running hot water only over the outer glass will allow the outer one to expand, while the inner glass remains relatively unchanged. This should loosen the outer glass and free it. 13.4Glasses 13.4Glasses 1) run hot water over them both 2) put hot water in the inner one 3) run hot water over the outer one 4) run cold water over them both 5) break the glasses Two drinking glasses are stuck, one inside the other. How would you get them unstuck?

7. A steel tape measure is marked such that it gives accurate length measurements at room temperature. If the tape measure is used outside on a very hot day, how will its length measurements be affected? 1) measured lengths will be too small 2) measured lengths will still be accurate 3) measured lengths will be too big 13.5aSteel Expansion I 13.5aSteel Expansion I

8. A steel tape measure is marked such that it gives accurate length measurements at room temperature. If the tape measure is used outside on a very hot day, how will its length measurements be affected? 1) measured lengths will be too small 2) measured lengths will still be accurate 3) measured lengths will be too big The tape measure will expand, so its markings will spread out farther than the correct amount. When it is laid down next to an object of fixed length, you will read too few markings for that given length, so the measured length will be too small. 13.5aSteel Expansion I 13.5aSteel Expansion I

9. 1) gets larger 2) gets smaller 3) stays the same 4) vanishes Metals such as brass expand when heated. The thin brass plate in the movie has a circular hole in its center. When the plate is heated, what will happen to the hole? 13.5bSteel Expansion II 13.5bSteel Expansion II

10. 1) gets larger 2) gets smaller 3) stays the same 4) vanishes This circle will expand outward along with the rest of the plate. Note that the material does NOT “expand inward” to fill the hole!! Imagine drawing a circle on the plate. This circle will expand outward along with the rest of the plate. Now replace the circle with the hole, and you can see that the hole will expand outward as well. Note that the material does NOT “expand inward” to fill the hole!! expansion Metals such as brass expand when heated. The thin brass plate in the movie has a circular hole in its center. When the plate is heated, what will happen to the hole? 13.5bSteel Expansion II 13.5bSteel Expansion II

11. Two objects are made of the same material, but have different masses and temperatures. If the objects are brought into thermal contact, which one will have the greater temperature change? 1) the one with the higher initial temperature 2) the one with the lower initial temperature 3) the one with the greater mass 4) the one with the smaller mass 5) the one with the higher specific heat 14.1aThermal Contact I 14.1aThermal Contact I

12. Two objects are made of the same material, but have different masses and temperatures. If the objects are brought into thermal contact, which one will have the greater temperature change? 1) the one with the higher initial temperature 2) the one with the lower initial temperature 3) the one with the greater mass 4) the one with the smaller mass 5) the one with the higher specific heat Since the objects are made of the same material, the only difference between them is their mass. Clearly, the object with less mass will be much easier to change temperature since there is not much material there (compared to the more massive object). 14.1aThermal Contact I 14.1aThermal Contact I

13. 14.2Two Liquids 14.2Two Liquids 1) the cooler one 2) the hotter one 3) both the same Two equal-mass liquids, initially at the same temperature, are heated for the same time over the same stove. You measure the temperatures and find that one liquid has a higher temperature than the other. Which liquid has a higher specific heat?

14. cooler liquid lower temperature Both liquids had the same increase in internal energy, because the same heat was added. But the cooler liquid had a lower temperature change. Q = mc  TQ m  T c Since Q = mc  T, if Q and m are both the same and  T is smaller, then c (specific heat) must be bigger. 14.2Two Liquids 14.2Two Liquids 1) the cooler one 2) the hotter one 3) both the same Two equal-mass liquids, initially at the same temperature, are heated for the same time over the same stove. You measure the temperatures and find that one liquid has a higher temperature than the other. Which liquid has a higher specific heat?

15. The specific heat of concrete is greater than that of soil. A baseball field (with real soil) and the surrounding parking lot are warmed up during a sunny day. Which would you expect to cool off faster in the evening when the sun goes down? 1) the concrete parking lot 2) the baseball field 3) both cool off equally fast 14.3aNight on the Field 14.3aNight on the Field

16. The specific heat of concrete is greater than that of soil. A baseball field (with real soil) and the surrounding parking lot are warmed up during a sunny day. Which would you expect to cool off faster in the evening when the sun goes down? 1) the concrete parking lot 2) the baseball field 3) both cool off equally fast The baseball field, with the lower specific heat, will change temperature more readily, so it will cool off faster. The high specific heat of concrete allows it to “retain heat” better and so it will not cool off so quickly – it has a higher “thermal inertia.” 14.3aNight on the Field 14.3aNight on the Field

17. 14.4Calorimetry 14.4Calorimetry 1 kg of water at 100 o C is poured into a bucket that contains 4 kg of water at 0 o C. Find the equilibrium temperature (neglect the influence of the bucket). 1) 0 o C 2) 20 o C 3) 50 o C 4) 80 o C 5) 100 o C

18. cold water mass is greater smaller temperature change Since the cold water mass is greater, it will have a smaller temperature change! The masses of cold/hot have a ratio of 4:1, so the temperature change must have a ratio of 1:4 (cold/hot). 14.4Calorimetry 14.4Calorimetry 1 kg of water at 100 o C is poured into a bucket that contains 4 kg of water at 0 o C. Find the equilibrium temperature (neglect the influence of the bucket). 1) 0 o C 2) 20 o C 3) 50 o C 4) 80 o C 5) 100 o C Q 1 = Q 2 m 1 c  T 1 = m 2 c  T 2  T 1 /  T 2 = m 2 / m 1

19. 14.5MoreCalorimetry 14.5More Calorimetry A 1 kg block of silver (c = 234 J/kg 0 C ) is heated to 100 0 C, then dunked in a tub of 1 kg of water (c = 4186 J/kg 0 C ) at 0 0 C. What is the final equilibrium temperature? 1) 0 o C 2) between 0 o C and 50 o C 3) 50 o C 4) between 50 o C and 100 o C 5) 100 o C

20. c water >> c silver more heat to change the temperature of the water than it does to change the temperature of the silver In other words, it is much “harder” to heat the water!! Since c water >> c silver it takes more heat to change the temperature of the water than it does to change the temperature of the silver. In other words, it is much “harder” to heat the water!! Thus, the final temperature has to be closer to the initial temperature of the water. 14.5MoreCalorimetry 14.5More Calorimetry A 1 kg block of silver (c = 234 J/kg 0 C ) is heated to 100 0 C, then dunked in a tub of 1 kg of water (c = 4186 J/kg 0 C ) at 0 0 C. What is the final equilibrium temperature? 1) 0 o C 2) between 0 o C and 50 o C 3) 50 o C 4) between 50 o C and 100 o C 5) 100 o C Q 1 = Q 2 mc 1  T 1 = mc 2  T 2  T 1 /  T 2 = c 2 / c 1

21. If you add some heat to a substance, is it possible for the temperature of the substance to remain unchanged? 1) yes 2) no 14.6Adding Heat 14.6Adding Heat

22. If you add some heat to a substance, is it possible for the temperature of the substance to remain unchanged? 1) yes 2) no Yes, it is indeed possible for the temperature to stay the same. This is precisely what occurs during a phase change – the added heat goes into changing the state of the substance (from solid to liquid or from liquid to gas) and does not go into changing the temperature! Once the phase change has been accomplished, then the temperature of the substance will rise with more added heat. 14.6Adding Heat 14.6Adding Heat

23. Will potatoes cook faster if the water is boiling faster? 1) yes 2) no 14.7Hot Potato 14.7Hot Potato

24. Will potatoes cook faster if the water is boiling faster? 1) yes 2) no The water boils at 100 °C and remains at that temperature until all of the water has been changed into steam. Only then will the steam increase in temperature. Since the water stays at the same temperature, regardless of how fast it is boiling, the potatoes will not cook any faster. 14.7Hot Potato 14.7Hot Potato

25. 14.8Water and Ice 14.8Water and Ice You put 1 kg of ice at 0 o C together with 1 kg of water at 50 o C. What is the final temperature? çL F = 80 cal/g çc water = 1 cal/g o C 1) 0 o C 2) between 0 o C and 50 o C 3) 50 o C 4) greater than 50 o C

26. How much heat is needed to melt the ice? Q = m L f = (1000g)  (80 cal/g) = 80,000 cal How much heat can the water deliver by cooling from 50 o C to 0 o C? Q = c water m  T = (1 cal/g o C)  (1000g)  (50 o C) = 50,000 cal Thus, there is not enough heat available to melt all the ice!! 14.8Water and Ice 14.8Water and Ice You put 1 kg of ice at 0 o C together with 1 kg of water at 50 o C. What is the final temperature? çL F = 80 cal/g çc water = 1 cal/g o C 1) 0 o C 2) between 0 o C and 50 o C 3) 50 o C 4) greater than 50 o C

27. 14.9Ice and Steam 14.9Ice and Steam You put 1 kg of ice at 0 o C together with 1 kg of steam at 100 o C. What is the final temperature? çL F = 80 cal/g, L v = 540 cal/g çc water = 1 cal/g o C 1) between 0 o C and 50 o C 2) 50 o C 3) between 50 o C and 100 o C 4) 100 o C 5) greater than 100 o C

28. How much heat is needed to melt the ice? Q = m L f = (1000g)  (80 cal/g) = 80,000 cal How much heat is needed to raise the water temperature to 100 o C? Q = c water m  T = (1 cal/g o C)  (1000g)  (100 o C) = 100,000 cal 540,000 cal But if all of the steam turns into water, that would release 540,000 cal. Thus, some steam is left over, and the whole mixture stays at 100 o C. 14.9Ice and Steam 14.9Ice and Steam You put 1 kg of ice at 0 o C together with 1 kg of steam at 100 o C. What is the final temperature? çL F = 80 cal/g, L v = 540 cal/g çc water = 1 cal/g o C 1) between 0 o C and 50 o C 2) 50 o C 3) between 50 o C and 100 o C 4) 100 o C 5) greater than 100 o C

29. 14.12Heat Conduction 14.12 Heat Conduction Given your experience of what feels colder when you walk on it, which of the surfaces would have the highest thermal conductivity? a) a rug b) a steel surface c) a concrete floor d) has nothing to do with thermal conductivity

30. 14.12Heat Conduction 14.12 Heat Conduction Given your experience of what feels colder when you walk on it, which of the surfaces would have the highest thermal conductivity? a) a rug b) a steel surface c) a concrete floor d) has nothing to do with thermal conductivity All things being equal, bigger k leads to bigger heat loss. From the packet: Steel=50, Concrete=0.8, Human body=0.17, Wool=0.04, in units of W/m*C 0 ).

31. Three Containers 1) container 1 2) container 2 3) container 3 4) all three are equal Three containers are filled with water to the same height and have the same surface area at the base, but the total weight of water is different for each. Which container has the greatest total force acting on its base?

32. Three Containers The pressure at the bottom of each container depends only on the height of water above it! This is the same for all the containers. The total force is the product of the pressure times the area of the base, but since the base is also the same for all containers, the total force is the same. 1) container 1 2) container 2 3) container 3 4) all three are equal Three containers are filled with water to the same height and have the same surface area at the base, but the total weight of water is different for each. Which container has the greatest total force acting on its base?

33. When you drink liquid through a straw, which of the items listed below is primarily responsible for this to work? 1) water pressure 2) gravity 3) inertia 4) atmospheric pressure 5) mass The Straw I

34. When you drink liquid through a straw, which of the items listed below is primarily responsible for this to work? 1) water pressure 2) gravity 3) inertia 4) atmospheric pressure 5) mass When you suck on a straw, you expand your lungs, which reduces the air pressure inside your mouth to less than atmospheric pressure. Then the atmospheric pressure pushing on the liquid in the glass provides a net upward force on the liquid in the straw sufficient to push the liquid up the straw. The Straw I

35. Wood in Water I Two beakers are filled to the brim with water. A wooden block is placed in the second beaker so it floats. (Some of the water will overflow the beaker.) Both beakers are then weighed. Which scale reads a larger weight? same for both

36. displaces an amount of water equal to its weight weight of the overflowed water is equal to the weight of the blockbeaker in B has the same weight as that in A The block in B displaces an amount of water equal to its weight, since it is floating. That means that the weight of the overflowed water is equal to the weight of the block, and so the beaker in B has the same weight as that in A. Wood in Water I Two beakers are filled to the brim with water. A wooden block is placed in the second beaker so it floats. (Some of the water will overflow the beaker.) Both beakers are then weighed. Which scale reads a larger weight? same for both

37. Two Bricks 1 2 1) greater 2) the same 3) smaller Imagine holding two identical bricks in place under water. Brick 1 is just beneath the surface of the water, while brick 2 is held about 2 feet down. The force needed to hold brick 2 in place is:

38. The force needed to hold the brick in place underwater is: W – F B. Since each brick displaces the same amount of fluid, then F B is the same in both cases. The force needed to hold the brick in place underwater is: W – F B. According to Archimedes’ Principle, F B is equal to the weight of the fluid displaced. Since each brick displaces the same amount of fluid, then F B is the same in both cases. Two Bricks 1 2 1) greater 2) the same 3) smaller Imagine holding two identical bricks in place under water. Brick 1 is just beneath the surface of the water, while brick 2 is held about 2 feet down. The force needed to hold brick 2 in place is:

39. Archimedes I 1) 1/4 2) 1/3 3) 4/3 4) 3/4 5) 2/1 An object floats in water with 3/4 of its volume submerged. What is the ratio of the density of the object to that of water?

40. Remember that we have: volume of the displaced water to the volume of the object is 3/43/4 the density of water so if the ratio of the volume of the displaced water to the volume of the object is 3/4, the object has 3/4 the density of water. 10.12aArchimedes I 10.12aArchimedes I 1) 1/4 2) 1/3 3) 4/3 4) 3/4 5) 2/1 An object floats in water with 3/4 of its volume submerged. What is the ratio of the density of the object to that of water?

41. 10.12bArchimedes II 10.12bArchimedes II 1) it floats just as before 2) it floats higher in the water 3) it floats lower in the water 4) it sinks to the bottom The object is now placed in oil with a density half that of water. What happens?

42. object has 3/4 the density of water 1/2 the density of waterdensity of the object is larger than the density of the oil We know from before that the object has 3/4 the density of water. If the water is now replaced with oil, which has 1/2 the density of water, the density of the object is larger than the density of the oil. Therefore, it must sink to the bottom. 10.12bArchimedes II 10.12bArchimedes II 1) it floats just as before 2) it floats higher in the water 3) it floats lower in the water 4) it sinks to the bottom The object is now placed in oil with a density half that of water. What happens?

43. 10.15aFluid Flow 10.15aFluid Flow (1) one quarter (2) one half (3) the same (4) double (5) four times Water flows through a 1-cm diameter pipe connected to a 1/2-cm diameter pipe. Compared to the speed of the water in the 1-cm pipe, the speed in the 1/2-cm pipe is:

44. A  r 2 radius is reduced by1/2area is reduced by 1/4speed must increase by 4 times (A  v) The area of the small pipe is less, so we know that the water will flow faster there. Since A  r 2, when the radius is reduced by 1/2, the area is reduced by 1/4, so the speed must increase by 4 times to keep the flow rate (A  v) constant. 10.15aFluid Flow 10.15aFluid Flow (1) one quarter (2) one half (3) the same (4) double (5) four times Water flows through a 1-cm diameter pipe connected to a 1/2-cm diameter pipe. Compared to the speed of the water in the 1-cm pipe, the speed in the 1/2-cm pipe is: v1v1 v2v2

45. On Golden Pond On Golden Pond 1) rises 2) drops 3) remains the same 4) depends on the size of the steel A boat carrying a large chunk of steel is floating on a lake. The chunk is then thrown overboard and sinks. What happens to the water level in the lake?

46. weight require a lot of displaced water only displaces its volume in water Initially the chunk of steel “floats” by sitting in the boat. The buoyant force is equal to the weight of the steel, and this will require a lot of displaced water to equal the weight of the steel. When thrown overboard, the steel sinks and only displaces its volume in water. This is not so much water -- certainly less than before -- and so the water level in the lake will drop. On Golden Pond 1) rises 2) drops 3) remains the same 4) depends on the size of the steel A boat carrying a large chunk of steel is floating on a lake. The chunk is then thrown overboard and sinks. What happens to the water level in the lake