21. [0.66/1 Points] DETAILS PREVIOUS ANSWERS OSCOLPHYSZO16 13.6.P.050. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) What is the vapor pressure (in Pa) of water at 25C ? 3171.47 Pa (b) What percentage of atmospheric pressure does this correspond to? 3.13 % (c) What percent of 25C air is water vapor if it has 100% relative humidity? (The density of dry air at 25C is 1.18 kg/ma.) 3.13 x % 1. [-/1 Points] DETAILS OSCOLPHYS2016 14.2.P.001. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER On a hot day, the temperature of a 77,000 L swimming pool increases by 1.40C. What is the net heat transfer (in J) during this heating? Ignore any complications, such as loss of water by evaporation. (Enter the magnitude.) + Additional Materials Reading 2. [-/1 Points] DETAILS OSCOLPHYS2016 14.2.P.003. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER To sterilize a 53.0 g glass baby bottle, we must raise its temperature from 16.0 C to 87.0C. How much heat transfer (in ]) is required? +3. [-I1 Points] OSCOLPHYSZO16 14.2.P.004. ASK YOUR TEACHER PRACTICE ANOTHER The same heat transfer into identical masses of different substances produces different temperature changes. Calculate the nal temperature in degrees Celsius when 1.50 kcal of heat enters 1.50 kg of the following, originally at 20.0C. (a) water (b) concrete (c) steel (d) mercury C C C C Additional Materials III Reading 4. [-/1 Points] OSCOLPHYSZO16 14.2.P.005. ASK YOUR TEACHER PRACTICE ANOTHER Rubbing your hands together warms them by converting work into thermal energy. If a woman rubs her hands back and forth for a total of 18 mbs, at a distance of 7.50 cm per rub, and with a frictional force of 30.0 N, what is the temperature increase in degrees Celsius? The mass of tissue warmed is only 0.100 kg, mostly in the palms and ngers. C 5. [-/1 Points] DETAILS OSCOLPHYSZO16 14.2.P.006. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER A 0.210 kg block of a pure material is heated from 20.0C to 71.1C by the addition of 4.15 k] of energy. Calculate its specic heat (in J/(kg ' C)). J/(kg ' C) Identify the substance of which it is most likely composed. copper " asbestos ' ' silver ' ' aluminum " glass Addlllonal Matarlals Il'l Reading 6. [-/1 Points] DETAILS OSCOLPHYSZO16 14.3.P.011. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER How much heat transfer (in kilocaluries) is required to thaw a 0.781 kg package of frozen vegetables originally at 0C if their heat of fusion is the same as that of water? kcal 7. [-/1 Points] OSCOLPHYSZO1614.3.P.014. ASKYOUR TEACHER PRACTICE ANOTHER The formation of condensation on a glass of ice water causes the ice to melt faster than it would otherwise. If 7.60 g of condensation forms on a glass containing water and 190 g of ice, how many grams will melt as a result? Assume no other heat transfer occurs. Use the heat of vaporization of water at 37, as an approximation, in this problem. 9 Addltlonel Materials III Reading 8. [-/1 Points] OSCOLPHYSZO1614.3.P.015. ASK YOUR TEACHER PRACTICE ANOTHER On a trip, you notice that a 4.12 kg bag of ice lasts an average of one day in your cooler. what is the average power in watts entering the ice if it starts at 0C and completely melts to 0C water in exactly one day? (1 watt = 1 joule/second or 1 W = 1 J/s.) W Addltlonel Materials III Reading 9. [-/1 Points] OSCOLPHYSZO1614.3.P.016. ASK YOUR TEACHER PRACTICE ANOTHER On a certain dry sunny day, a swimming pool's temperature would rise by 1.40C if not for evaporation. What fraction of the water must evaporate to carry away precisely enough heat to keep the temperature constant? 10. [-/1 Points] OSCOLPHV52016 14.3.P.018. ASK YOUR TEACHER PRACTICE ANOTHER In 1986, a gargantuan iceberg broke away from the Ross Ice Shelf in Antarctica. It was approximately a rectangle 160 km long, 45.0 km wide, and 250 m thick. (a) What is the mass of this iceberg in kg, given that the density of ice is 917 kg/m3? k9 (b) How much heat transfer (in joules) is needed to melt it? J (c) How many years would it take sunlight alone to melt ice this thick, if the ice absorbs an average of 110 W/mz, 11.00 h per day? yr Addltlonal Materlals E] Reading 11. [-/1 Points] DETAILS OSCOLPHYSZO16 14.5.P.030. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) Calculate the rate of heat conduction (in W) through house walls that are 13.5 cm thick and that have an average thermal conductivity twice that of glass wool. Assume there are no windows or doors. The surface area of the walls is 155 m2 and their inside surface is at 22.0C, while their outside surface is at 500C. W (b) How many 1 kW room heaters would be needed to balance the heat transfer due to conduction? (Round your answer to the next whole integer.) 1 kw room heaters 12. [-I1 Points] DETAILS OSCOLPHYSZO16 14.5.P.031. I MYNOTES ll ASKYOURTEACHER I PRACTICEANOTHER The rate of heat conduction out of a window on a winter day is rapid enough to chill the air next to it. To see just how rapidly windows transfer heat by conduction, calculate the rate of conduction in watts through a 2.50 rn2 window that is 0.625 cm thick if the temperatures of the inner and outer surfaces are 5.00C and 10.0C, respectively. This rapid rate will not be maintainedthe inner surface will cool, and even result in frost formation. W Additional Materials III Reading 13. [-/1 Points] DETAILS OSCOLPHY52016 14.5.P.032. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Calculate the rate of heat conduction (in W) out of the human body, assuming that the core internal temperature is 37.0C, the skin temperature is 34.0C, the thickness of the tissues between averages 1.09 cm, and the surface area is 1.36 m2. W Additional Materials ID Reading 14. [-I1 Points] DETAILS OSCOLPHYSZO16 14.6.P.045. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER At what wind speed (in m/s) does 20C air cause the same chill factor as still air at 34C? (Use the data from this table to answer this question.) m/s 15. [/1 Points] OSCOLPHYSZO16 14.6.P.047. ASK YOUR TEACHER PRACTICE ANOTHER The "steam\" above a freshly made cup of instant coffee is really water vapor droplets condensing alter evaporating from the hot coffee. What is the nal temperature (in C) of 260 g of hot coffee initially at 850C if 1.50 g evaporates from it? The coffee is in a Styrofoam cup, and so other methods of heat transfer can be neglected. Assume that coffee has the same physical properties as water. C Additional Materials III Reading 16. [-/1 Points] OSCOLPHYSZO16 14.6.P.048. ASK YOUR TEACHER PRACTICE ANOTHER (a) How many kilograms of water must evaporate from a 57.2 kg woman to lower her body temperature by 0.755C? k9 (b) Is this a reasonable amount of water to evaporate in the form of perspiration, assuming the relative humidity of surrounding air is low? Yes No 17. [-11 Points] DETAILS OSCOLPHYSZO16 14.7.P.055. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER At what net rate (in kW) does heat radiate from a 280 m2 black roof on a night when the roof's temperature is 31.0C and the surrounding temperature is 16.0C? The emissivity of the roof is 0.900. (Enter the magnitude.) kW Addltlonal Materials I3 Reading 18. [/1 Points] DETAILS OSCOLPHYSZO16 14.7.P.057. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Radiation makes it impossible to stand close to a hot lava ow. Calculate the rate of heat transfer by radiation in kilowatls from 1.00 m2 of 1240C fresh lava into 25.0C surroundings, assuming lava's emissivity is 1. kW 19. [/1 Points] OSCOLPHYSZO16 14.7.P.058. ASK YOUR TEACHER PRACTICE ANOTHER (a) Calculate the rate of heat transfer (in W) by radiation from a car radiator at 111C into a 46.0C environment, if the radiator has an emissivity of 0.750 and a 1.25 m2 surface area. W (b) Is this a signicant fraction of the heat transfer by an automobile engine? To answer this, assume a horsepower of 200 hp (150 kW) and the efciency of automobile engines as 25%. " No, this is less than 1% of the heat transfer by an automobile engine. ' ' Yes, this is between 50% and 100% of the heat transfer by an automobile engine. " No, this is between 1% and 5% of the heat transfer by an automobile engine. ' ' Yes, this is between 5% and 50% of the heat transfer by an automobile engine. Additional Materials DJ Reading ASK YOUR TEACHER PRACTICE ANOTHER (a) Calculate the rate of heat transfer in watts to you by radiation given your skin temperature is 37.0C, the emissivity of skin is 0.98, and the surface area of your body is 1.35 m2. W 20. [-11 Points] OSCOLPHYSZO16 14.7.P.060. Suppose you walk into a sauna that has an ambient temperature of 52.0C. (b) If all other forms of heat transfer are balanced (the net transfer is zero), at what rate will your body temperature increase in degrees Celsius per minute if your mass is 68 kg? C/min