Question

1. The formula ∆? = ???∆? is only good if ∆? is not too large. According to your textbook, what is considered a “not too large ∆??” (a) ∆? ≈ 1 ?° or less (c) ∆? < 100 ?° or so (b) ∆? ≈ 10 ?° or less (d) ∆? < 200 ?° or so

2. In the formula ∆? = ???∆?, what is ?? (a) The specific heat of the substance (b) The thermal resistivity of the substance (c) The latent heat of fusion of the substance (d) The coefficient of thermal expansion of the substance (e) One-third of the coefficient of linear thermal expansion of the substance.

3. Find this passage in section 17.4 and fill in the blank. This is an important statement: For ___________ materials we can find a simple relationship between the volume expansion coefficient  and the linear expansion coefficient  . (a) most (d) frozen (b) all (e) liquid (c) solid

4. What is that simple relationship between ? and ?? (a) ? = 3? (d) ? = 1 3 ? (b) ? = 2? (e) ? = 3 2 ? (c) ? = 1 2 ? 5. The table of coefficients of expansion in the textbook lists ? for glycerin as 49 × 10−5 K−1. Would it be correct, then, to say that ? for glycerin must be about 16.3 × 10−5 K−1 (a) Sure, if ∆? is not too large, as specified before. (b) No, we cannot specify ? for a substance like glycerin.

6. Which of the following is the most reasonable problem-solving approach? (a) We can always use ∆? = ???∆? when dealing with solids; but we use ∆? = ?? ?∆? when dealing with gases or liquids. (b) We can always use ∆? = ???∆? and cube the result if we want ∆?. (c) Apply ∆? = ???∆? to the longest dimension of an object only. (d) We can use ∆? = ???∆? only for metals; for all other substances use ∆? = ?? ?∆?.

7. Two cylinders made of the same material and have the same external dimensions, but one is solid and the other is hollow. Their temperature is increased to the same final temperature and they expand. How will their final sizes compare? (a) They will still have the same external dimensions. (b) The hollow one will be larger. (c) The solid one will be larger.

8. Why is it sometimes possible to loosen metal caps on screw-top glass jars by dipping the capped jar briefly into hot water? (a) The hot water makes the cap expand, but not the bottle. (b) The hot water makes the bottle contract while the cap expands. (c) The metal cap expands more than the glass bottle for the same T.

9. Go to Page 547 and look at Figure 17.3 that shows a bimetallic strip. A bimetallic strip is made by bonding two different materials that have the same dimensions at the same initial common temperature. Suppose that in Figure 17.3 metal 1 is copper. Which of the following materials could be used for metal 2? (a) Steel (b) Invar (nickel-iron alloy) (c) Brass

10. The figure shows a rectangular brass plate at 0°C in which there is cut a rectangular hole of dimensions indicated. If the temperature of the plate is raised to 150°C: (a) x will increase and y will decrease (b) both x and ywill decrease (c) x will decrease and y will increase (d) both x and ywill increase (e) the changes in x and y depend on z

11. When water at 2°C absorbs heat, what happens? (a) It melts while its volume increases. (b) It warms up while its volume increases. (c) It cools down while its volume decreases. (d) It vaporizes as it cools down. (e) It warms up while its volume decreases.

12. The coefficient of linear expansion of steel is 12 x 10–6 /C°. A railroad track is made of individual rails of steel 1.0 km in length. By what length would these rails change between a cold day when the temperature is –10°C and a hot day at 30°C? (a) 0.62 cm (d) 480 cm (b) 24 cm (e) 620 cm (c) 48 cm

13. A steel tank of volume 0.0700 m3 is filled to the top with gasoline at 20.0°C. The tank is placed inside a chamber at a temperature of 50.0°C. The coefficient of volume expansion for gasoline is 9.50 x 10–4 /C°; and the coefficient of linear expansion of steel is 12.0 x 10–6 /C°. After the tank and its contents reach thermal equilibrium with the chamber, how much gasoline has spilled? (a) 2.52 x 10–5 m3 (b) 7.56 x 10–5 m3 (c) 1.69 x 10–3 m3 (d) 1.92 x 10–3 m3 (e) 3.00 x 10–3 m3   

14. A copper plate has a length of 0.12 m and a width of 0.10 m at 25°C. The plate is uniformly heated to 175°C. If the linear expansion coefficient for copper is 1.7 x 10–5 /C°, what is the change in area of the plate as a result of the increase in temperature? (a) 2.6 x 10–5 m2 (b) 6.1 x 10–5 m2 (c) 3.2 x 10–5 m2 (d) 4.9 x 10–5 m2 (e) 7.8 x 10–5 m2

15. A ring made of steel has a 2.5000-in inside diameter when the temperature is 20.0°C. The ring will be warmed until it can fit around a brass rod of 2.5020-in outer diameter. Calculate to what temperature should the ring be warmed. (a) 83.4 °C (b) 86.7 °C (c) 82.1 °C (d) 833 °C (e) 66.6 °C  

16. During heat conduction, the heat transfer (“heat flow”) is always (a) From higher to lower temperature (b) From lower to higher temperature (c) Could be either way, depending on the type of material

17. According to the textbook, why are many insulating materials such as Styrofoam and fiberglass good insulators? (a) Because they are always colder than the environment. (b) Because they tend to have low specific heats. (c) Because they contain mostly dead air. (d) Because they cannot be heated. (e) Because their melting points are very high.

18. Which of the three modes of heat transfer is the one that depends on moving matter from one region to another? (a) Conduction only. (d) Both conduction and convection. (b) Convection only. (e) None of them – heat is not matter. (c) Radiation only.

19. You will use fiberglass to insulate a house. If a space 6 inches wide (that’s 15.24 cm) is to be completely filled with fiberglass, what will be the thermal resistance of the fiberglass layer? (a) 0.0061 m2·K/W (d) 3.81 m2·K/W (b) 0.260 m2·K/W (e) 150 m2·K/W (c) 2.23 m2·K/W

20. You need to come up with a layer of material that provides a thermal resistance of 20 W/m·K. Which of the following will give you that resistance with the thinnest layer? (a) Brick, red (d) Glass (b) Styrofoam (e) Felt
21. This diagram shows four slabs of different materials with equal thickness, placed side by side. The temperatures at the interfaces are shown. Assume heat conduction is happening at a steady rate. Rank the materials according to their thermal conductivities, lowest to highest. (a) 3, 4, 2, 1 (b) 4, 3, 2, 1 (c) 1, 2, 3, 4 (d) 2, 1, 3, 4 (e) 3, 4, 1, 2   

22. At what rate is heat lost through a 1.0m x 1.5m rectangular glass window that is 0.5 cm thick when the inside temperature is 20°C and the outside temperature is 5°C? (a) 18 W (d) 3600 W (b) 36 W (e) 7200 W (c) 720 W

23. A granite wall has a thickness of 0.61 m and a thermal conductivity of 2.1 W/m·K. The temperature on one face of the wall is 3.2 °C. The other face is at 20.0°C. How much heat is transferred in one hour through each square meter of the granite wall? (a) 2.1 x 105 J (d) 1800 J (b) 1.1 x 105 J (e) 58 J (c) 7.7 x 104 J

Questions 24, 25 and 26 are about the following situation: A cooking pan placed on a stove has a copper bottom that is 8.50 mm thick and 0.150 m2 in area. The water inside the pan is at 100.0°C and 0.390 kg are being evaporated every 3.00 min.

24. How much heat energy is needed to evaporate each 0.390 kg of water? (a) 8.80 x 105 J (b) 1.30 x 105 J (c) 1.63 x 105 J (d) 7.52 x 105 J

25. At what rate is the heat being supplied by the stove? (a) 2.93 x 105 W (b) 7.22 x 102 W (c) 9.06 x 102 W (d) 4.89 x 103 W

26. What is the temperature of the bottom surface of the pan (the surface in contact with the stove)? (a) 143.13°C (b) 100.72 °C (c) 100.11 °C (d) 118.24 °C

27. A 150-W filament lightbulb is operating at a temperature of 2450 K. The emissivity of the surface of the filament material is 0.350. Assuming all the 150-W are radiative power, calculate the surface area of the filament. (a) 2.1 x 10-4 m2 (b) 3.1 x 10-6 m2 (c) 4.4 x 10-4 m2 (d) 7.4 x 10-5 m2 Questions 28 and 29 are about the following situation: The surface area of your body is approximately 1.71 m2. The emissivity of dry skin is approximately 0.891. The normal skin-surface temperature is 33.3 °C.

Assume you are in a room where the temperature is a constant 20.0 °C. 28. What is the radiation current your skin receives from the room environment? (a) 2.53 x 10-5 W (b) 1.38 x 10-2 W (c) 66.8 W (d) 638.0 W (e) 1256 W

29. What is the net radiation power of your skin? Is it a net input or a net output? (a) 0.0924 W, a net output (b) 0.106 W, a net input (c) 2.70 x 10-3, a net output (d) 123.9 W, a net output (e) 638.0 W, a net input



30. What is the power output of radiation of this person’s body? (Just the output, not the net.) (a) 0.0024 W (d) 815 W (b) 0.092 W (e) 958 W (c) 143 W 31. What is the power of radiation absorption from the surroundings for this person? (a) 0.0024 W (d) 815 W (b) 0.012 W (e) 958 W (c) 143 W 32. The net radiation power is only about 80% of the basal metabolic rate. What is the basal metabolic rate of this person? (a) 179 W (d) 0.00294 W (b) 114 W (e) 0.099 W (c) 1019 W   

Answer 1

1. ∆? = ???∆? , typically for solids the order is about 100⁰C or less. but the question is referring to a particular textbook, so it is informative if the textbook is provided. if the temperature change is large we must integrate dL = ???d?

2. is the coefficient of linear expansion, so option d) The coefficient of thermal expansion of the substance is the correct answer. its value depends on the material

3. For solids the volume expansion is ∆V = βVo∆T and the relation between β and is given as β = 3 , hence answer is c) solid

4. a) β = 3 is valid for solids, for liquids and gases only coefficient of volume expansion is defined. b) we cannot specify for glycerin

6. option a)  We can always use ∆? = ???∆? when dealing with solids; but we use ∆? = ?? ?∆? when dealing with gases or liquids, is correct since we cannot define coefficient of linear expansion for fluids.

7. solid cylinder follows volume expansion ∆V = βVo∆T, whereas the hollow cylinder follows area expansion ∆A = Vo∆T and = 2, so the solid one will expand more.

8. option c) is correct different materials have different coefficient of thermal expansion. glass has value less than metals.

9.   = 17 x 10^-6/⁰C for copper and Brass has 19 x 10^-6/⁰C , if metal 1, copper is above the brass it expands less than brass because of their   values. it looks as u shaped after heating. if metal 1, copper is below the brass it will bend as inverted u.

11. Water has a peculiar property in 0 to 4⁰C range, it will contract if the heat is supplied. above 4⁰C it expands normally when heat is supplied. option e) is correct, it warms up while its volume decreases

12. option c) 48 cm.

∆? = 12 x 10–6 /C° x 1 x10⁵cm x 40 C°

∆? = 48 cm

13.

∆V = βVo∆T (for gasoline)

∆T = 30C°, β = 9.50 x 10–4 /C°

V₀=0.0700 m³

∆V = 9.50 x 10–4 /C° x 0.0700 m³ x 30C°

∆V = 19.95 x x 10–4 m³

the tank itself has increased its volume, so ∆V for tank is

∆V' = 3 x 12.0 x 10–6 /C° x 0.0700 m³ x 30C°

∆V' = 0.756 x 10^-4 m³

so, the volume change in gasoline is the difference  ∆V -∆V'

i.e., 1.92 x 10^-3m³

hope, you could solve the other problems. i have done as many as possible within the limited time alloted for a question.