Concept explainers
(a) The number of kilocalories in food is determined by calorimetry techniques in which the food is burned and the amount at
Trending nowThis is a popular solution!
Chapter 14 Solutions
COLLEGE PHYSICS
Additional Science Textbook Solutions
Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
Tutorials in Introductory Physics
University Physics with Modern Physics (14th Edition)
College Physics (10th Edition)
Conceptual Physics (12th Edition)
- In 1993, the U.S. government instituted a requirement that all room air conditioners sold in the United States must have an energy efficiency ratio (EER) of 10 or higher. The EER is defined as the ratio of the cooling capacity of the air conditioner, measured in British thermal units per hour, or Btu/h, to its electrical power requirement in watts. (a) Convert the EER of 10.0 to dimensionless form, using the conversion 1 Btu = 1 055 J. (b) What is the appropriate name for this dimensionless quantity? (c) In the 1970s, it was common to find room air conditioners with EERs of 5 or lower. State how the operating costs compare for 10 000-Btu/h air conditioners with EERs of 5.00 and 10.0. Assume each air conditioner operates for 1 500 h during the summer in a city where electricity costs 17.0 per kWh.arrow_forwardBeryllium has roughly one-half the specific heat of water (H2O). Rank the quantities of energy input required to produce the following changes from the largest to the smallest. In your ranking, note any cases of equality, (a) raising the temperature of 1 kg of H2O from 20C to 26C (b) raising the temperature of 2 kg of H2O from 20C to 23C (c) raising the temperature of 2 kg of H2O from 1C to 4C (d) raising the temperature of 2 kg of beryllium from 1C to 2C (e) raising the temperature of 2 kg of H2O from -1C to 2Carrow_forwardOne of a dilute diatomic gas occupying a volume of 10.00 L expands against a constant pressure of 2.000 atm when it is slowly heated. If the temperature of the gas rises by 10.00 K and 400.0 J of heat are added in the process, what is its final volume?arrow_forward
- An aluminum rod 0.500 m in length and with a cross-sectional area of 2.50 cm2 is inserted into a thermally insulated vessel containing liquid helium at 4.20 K. The rod is initially at 300 K. (a) If one-half of the rod is inserted into the helium, how many liters of helium boil off by the time the inserted half cools to 4.20 K? Assume the upper half does not yet cool. (b) If the circular surface of the upper end of the rod is maintained at 300 K, what is the approximate boil-off rate of liquid helium in liters per second after the lower half has reached 4.20 K? (Aluminum has thermal conductivity of 3 100 W/m K at 4.20 K; ignore its temperature variation. The density of liquid helium is 125 kg/m3.)arrow_forwardFor a temperature increase of 10 at constant volume, what is the heat absorbed by (a) 3.0 mol of a dilute monatomic gas; (b) 0.50 mol of a dilute diatomic gas; and (c) 15 mol of a dilute polyatomic gas?arrow_forwardEqual masses of substance A at 10.0C and substance B at 90.0C are placed in a well-insulated container of negligible mass and allowed to come to equilibrium. If the equilibrium temperature is 75.0Q which substance has the larger specific heat? (a) substance A (b) substance B (c) The specific heats are identical. (d) The answer depends on the exact initial temperatures. (e) More information is required.arrow_forward
- A person inhales and exhales 2.00 L of 37.0C air, evaporating 4.00 X 10-2 g of water from the lungs and breathing passages with each breath. (a) How much heat transfer occurs due to evaporation in each breath? (b) What is the rate of heat transfer in watts if the person is breathing at a moderate rate of 18.0 breaths per minute? (c) If the inhaled air had a temperature of 20.0C, what is the rate of heat transfer for warming the air? (d) Discuss the total rate of heat transfer as it relates to typical metabolic rates. Will this breathing be a major form of heat transfer for this person?arrow_forwardIn very cold weather, a significant mechanism for heat loss by the human body is the energy expended in warming the air taken into the lungs with each breath. (a) On a cold winter day when the temperature is - 20 ℃, what amount of heat is needed to warm body temperature (37 ℃) the 0.60 L of air exchanged with each breath? Assume that the specific heat of air is 1020 J/kg.K and that 1.0 L of air has a mass of 1.3 x 10-3 kg. (b) How much heat is lost per hour if the respiration rate is 20 breaths per minute?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 melting 900 kg ofice? (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
- A small electric immersion heater is used to heat 79 g of water for a cup of instant coffee. The heater is labeled “72 watts" (it converts electrical energy to thermal energy at this rate). Calculate the time required to bring all this water from 20°C to 100°C, ignoring any heat losses. (The specific heat of water is 4186 J/kg-K.) Number Unitsarrow_forwardSuppose 8.50 x 10° J of energy are transferred to 1.79 kg of ice at 0°C. The latent heat of fusion and specific heat of water are L; = 3.33 x 10° J/kg and c = 4186 (kg · °C) HINT (a) Calculate the energy (in J) required to melt all the ice into liquid water. (Enter your answer to at least three significant figures.) (b) How much energy (in J) remains to raise the temperature of the liquid water? (Enter your answer to at least three significant figures.) (c) Determine the final temperature of the liquid water in Celsius. °Carrow_forward(a) Two 33 g ice cubes are dropped into 180 g of water in a thermally insulated container. If the water is initially at 27°C, and the ice comes directly from a freezer at -21°C, what is the final temperature at thermal equilibrium? (b) What is the final temperature if only one ice cube is used? The specific heat of water is 4186 J/kg-K. The specific heat of ice is 2220 J/kg•K. The latent heat of fusion is 333 kJ/kg. (a) Number Units (b) Number Unitsarrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningCollege PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage Learning