College Physics: A Strategic Approach (4th Edition)
4th Edition
ISBN: 9780134609034
Author: Randall D. Knight (Professor Emeritus), Brian Jones, Stuart Field
Publisher: PEARSON
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Question
Chapter 11, Problem 22CQ
To determine
The signs of
W
Q
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If you hold a rubber band loosely between two fingers and then stretch it, you can tell by touching it to the sensitive skin of your forehead that stretching the rubber band has increased its temperature. If you then let the rubber band rest against your forehead, it soon returns to its original temperature. What are the signs of W and Q for the entire process?
Thermal energy is being transferred through a 0.8 mm layer of human skin at a rate of 1.1 x 104 W/m2. The room temperature is 27 °C.Determine the thermal conductivity of the skin.
note: if you think you need to have more information to solve this problem, you can make assumptions. Please state them clearly in your answer, if you need to make such assumptions.
During a chemistry lab, you take a 0.4 kg sample of ice and put it in a beaker with a thermometer. You then place the beaker with the ice on
0 the temperature of the ice is -18
=
a hot plate, and turn on the hot plate. This hot plate adds heat to the ice at a rate of 330 W. At time t
°C.
Because of the large heat capacity of water and ice, you may assume in this problem that all the heat goes into the sample of ice, and that
we can ignore the amount of heat going into the beaker and thermometer. Also assume no heat escapes from the system.
Some useful values:
●
Specific heat of water: C =
Specific heat of ice: Ci
= 2100 J/kg K
• Latent heat of fusion: L = 334 000 J/kg
●
4200 J/kg K
=
1a) At what time does the ice reach a temperature of -3.5°C?
answer=
units?
1b) At what time has all the ice melted?
answer=
units?
Check your answer
Check your answer
1c) After the ice has completely melted, we're left with 0.4 kg of water.
Check your answer
answer=
units?
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Chapter 11 Solutions
College Physics: A Strategic Approach (4th Edition)
Ch. 11 - Rub your hands together vigorously. What happens?...Ch. 11 - Describe the energy transfers and transformations...Ch. 11 - According to Table 11.4, cycling at 15 km/h...Ch. 11 - Prob. 4CQCh. 11 - Prob. 5CQCh. 11 - For most automobiles, the number of miles per...Ch. 11 - Prob. 8CQCh. 11 - Prob. 9CQCh. 11 - Prob. 10CQCh. 11 - Prob. 11CQ
Ch. 11 - Prob. 12CQCh. 11 - For Questions 12 through 17, give a specific...Ch. 11 - For Questions 12 through 17, give a specific...Ch. 11 - For Questions 12 through 17, give a specific...Ch. 11 - For Questions 12 through 17, give a specific...Ch. 11 - For Questions 12 through 17, give a specific...Ch. 11 - For Questions 12 through 17, give a specific...Ch. 11 - Prob. 19CQCh. 11 - Prob. 20CQCh. 11 - Prob. 21CQCh. 11 - Prob. 22CQCh. 11 - Prob. 24CQCh. 11 - Prob. 25CQCh. 11 - Electric vehicles increase speed by using an...Ch. 11 - When the suns light hits the earth, the...Ch. 11 - Prob. 29CQCh. 11 - Prob. 30CQCh. 11 - Prob. 31CQCh. 11 - Prob. 32MCQCh. 11 - Prob. 33MCQCh. 11 - A person is walking on level ground at constant...Ch. 11 - A person walks 1 km, turns around, and runs back...Ch. 11 - 200 J of heat is added to two gases, each in a...Ch. 11 - Prob. 37MCQCh. 11 - A refrigerators freezer compartment is set at 10C;...Ch. 11 - A 10% efficient engine accelerates a 1500 kg car...Ch. 11 - Prob. 2PCh. 11 - A typical photovoltaic cell delivers 4.0 103 W of...Ch. 11 - Prob. 4PCh. 11 - Prob. 5PCh. 11 - Prob. 6PCh. 11 - In an average human, basic life processes require...Ch. 11 - Prob. 8PCh. 11 - An energy bar contains 22 g of carbohydrates. How...Ch. 11 - Prob. 10PCh. 11 - Prob. 11PCh. 11 - Prob. 12PCh. 11 - An energy bar contains 22 g of carbohydrates. If...Ch. 11 - Prob. 14PCh. 11 - Prob. 15PCh. 11 - Prob. 16PCh. 11 - The label on a candy bar says 400 Calories....Ch. 11 - Prob. 18PCh. 11 - A weightlifter curls a 30 kg bar, raising it each...Ch. 11 - Prob. 20PCh. 11 - Prob. 21PCh. 11 - Prob. 22PCh. 11 - Suppose your body was able to use the chemical...Ch. 11 - Prob. 24PCh. 11 - Prob. 25PCh. 11 - Prob. 26PCh. 11 - Prob. 27PCh. 11 - The planet Mercurys surface temperature varies...Ch. 11 - A piece of metal at 100C has its Celsius...Ch. 11 - Prob. 30PCh. 11 - 500 J of work are done on a system in a process...Ch. 11 - Prob. 32PCh. 11 - 600 J of heat energy are transferred to a system...Ch. 11 - 10 J of heat are removed from a gas sample while...Ch. 11 - A heat engine extracts 55 kJ from the hot...Ch. 11 - A heat engine does 20 J of work while exhausting...Ch. 11 - A power plant running at 35% efficiency generates...Ch. 11 - A heat engine operating between energy reservoirs...Ch. 11 - A newly proposed device for generating electricity...Ch. 11 - Prob. 41PCh. 11 - Prob. 42PCh. 11 - Prob. 43PCh. 11 - Prob. 44PCh. 11 - A refrigerator takes in 20 J of work and exhausts...Ch. 11 - Air conditioners are rated by their coefficient of...Ch. 11 - 50 J of work are done on a refrigerator with a...Ch. 11 - Prob. 48PCh. 11 - Find the maximum possible coefficient of...Ch. 11 - Prob. 50PCh. 11 - Prob. 51PCh. 11 - Prob. 52PCh. 11 - Prob. 53PCh. 11 - Prob. 55GPCh. 11 - Prob. 56GPCh. 11 - The record time for a Tour de France cyclist to...Ch. 11 - Championship swimmers take about 22 s and about 30...Ch. 11 - A 68 kg hiker walks at 5.0 km/h up a 7% slope....Ch. 11 - To make your workouts more productive, you can get...Ch. 11 - The resistance of an exercise bike is often...Ch. 11 - Prob. 62GPCh. 11 - Prob. 63GPCh. 11 - An engine does 10 J of work and exhausts 15 J of...Ch. 11 - An engine operating at maximum theoretical...Ch. 11 - An engineer claims to have measured the...Ch. 11 - A typical coal-fired power plant burns 300 metric...Ch. 11 - Prob. 68GPCh. 11 - Air conditioners sold in the United States are...Ch. 11 - The surface waters of tropical oceans are at a...Ch. 11 - The light energy that falls on a square meter of...Ch. 11 - Prob. 72MSPPCh. 11 - Prob. 73MSPPCh. 11 - Prob. 74MSPPCh. 11 - Prob. 75MSPPCh. 11 - Prob. 76MSPPCh. 11 - Prob. 77MSPPCh. 11 - Prob. 78MSPPCh. 11 - Prob. 79MSPP
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- Why is a person able to remove a piece of dry aluminum foil from a hot oven with bare fingers, whereas a burn results if there is moisture on the foil?arrow_forwardThe surface area of an unclothed person is 1.50 m2, and his skin temperature is 33.0C. The person is located in a dark room with a temperature of 20.0C, and the emissivity of the skin is e = 0.95. (a) At what rate is energy radiated by the body? (b) What is the significance of the sign of your answer?arrow_forwardWhen the metal ring and metal sphere in Figure CQ19.8 are both at room temperature, the sphere can barely be passed through the ring, (a) After the sphere is warmed in a flame, it cannot be passed through the ring. Explain, (b) What If? What if the ring is warmed and the sphere is left at room temperature? Does the sphere pass through the ring?arrow_forward
- (a) What is the rate of heat conduction through the 3.00-cm-thick fur of a large animal having a I .40-m surface area? Assume that the animal's skin temperature is 32.0 , that the air temperature is 5.00 , and that has the same thermal conductivity as air. (b) What food intake will the animal need in one day to replace this heat transfer?arrow_forwardIn 1986, a gargantuan iceberg broke away from the Ross Ice Shelf in Antarctica. It was approximately a rectangle 160 km long, 40.0 km wide, and 250 m thick. (a) What is the mass of this iceberg, given that the density of ice is 917kg/m3 ? (b) How much heat transfer (in joules) is needed to melt it? (c) How many years would it take sunlight alone to melt ice this thick, if the ice absorbs an average of 100W/m2, 12.00 h per day?arrow_forwardIn an air conditioner, 12.65 MJ of heat transfer occurs from a cold environment in 1.00 h. (a) What mass of ice melting would involve the same heat transfer? (b) How many hours of operation would be equivalent to mailing 900 kg of ice? (c) If ice costs 20 cents per kg, do you think the air conditioner could be operated more cheaply than by simply using ice? Describe in detail how you evaluate the relative costs.arrow_forward
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