Quiz 14: Temperature and Heat

If it is given that 546 K equals 273C, then it follows that 423 K equals: A) 127C. B) 150C. C) 473C. D) 1200C.

A temperature change from 15C to 45C corresponds to what incremental change in F? A) 54 B) 40 C) 36 D) 313

A substance is heated from 15C to 45C. What would the same incremental change be when registered in kelvins? A) 20 B) 40 C) 30 D) 313

At what temperature is the same numerical value obtained in Celsius and Fahrenheit? A) 40 B) 0 C) 40 D) 72

Normal body temperature for humans is 37C. What is this temperature in kelvins? A) 296 B) 310 C) 393 D) 273

Carbon dioxide forms into a solid (dry ice) at approximately 157F. What temperature in degrees Celsius does this correspond to? A) 157C B) 93C C) 105C D) 121C

An interval of one Celsius degree is equivalent to an interval of: A) one Fahrenheit degree. B) one kelvin. C) 5/9 Fahrenheit degree. D) 5/9 kelvin.

A temperature of 233 K equals which of the following? A) 506C B) 40C C) -40F D) 40F

Of the following systems, which contains the most heat? A) 100 kg of water at 80°C B) 250 kg of water at 40°C C) 600 kg of ice at 0°C D) Systems do not contain heat.

Calories of the food type are equal to which of the following? A) 4.186 J B) 4186 J C) 1 BTU D) 1054 J

If heat is flowing from a table to a block of ice moving across the table, which of the following must be true? A) The table is rough, and there is friction between the table and ice. B) The ice is cooler than the table. C) The ice is changing phase. D) All three are possible, but none is absolutely necessary.

How many calories are equal to one BTU? (One calorie = 4.186 J, one BTU = 1054 J.) A) 0.252 B) 3.97 C) 252 D) 397

Which of the following statements is true? A) A hot object contains a lot of heat. B) A cold object contains only a little heat. C) Objects do not contain heat. D) Statements a and b are true.

Arrange the temperatures , , and from highest to lowest. A) , , B) , , C) , , D) , ,

Arrange the following units, Calorie, calorie, and Joule from smallest to largest. A) Joule, Calorie, calorie B) calorie, Calorie, Joule C) Joule, calorie, Calorie D) Answers a and c are both correct, it apparently is a trick question.

Which best describes the relationship between two systems in thermal equilibrium? A) No net energy is exchanged. B) Volumes are equal. C) Masses are equal. D) The velocity is zero.

What is the temperature of a system in thermal equilibrium with another system made up of water and steam at one atmosphere of pressure? A) 0F B) 273 K C) 0 K D) 100C

What is the temperature of a system in thermal equilibrium with another system made up of ice and water at one atmosphere of pressure? A) 0F B) 273 K C) 0 K D) 100C

Which best describes a system made up of ice, water, and steam existing together? A) absolute zero B) triple point C) ice point D) steam point

Pennies used to be made of copper, but now they are made of copper-coated zinc. If one were to do a precise calorimetry experiment to determine the specific heat of the new pennies, what would be the result to be? A) It would be that of copper since copper is on the outside. B) It would be that of zinc since zinc is in the center. C) It would be the sum of the copper and zinc specific heats. D) It would be between that of copper and that of zinc, depending on coating thickness.

A plot of the temperature versus the energy per kg added to a piece of ice as it goes from below freezing at -10C to becoming steam at 110C consists of straight lines, some horizontal and some with an upward slope. What do the upward slopes represent? A) specific heats B) reciprocals of specific heats C) latent heats D) reciprocals of latent heats

A 20-kg piece of aluminum (which has a specific heat of 900 J/kg ·C) is warmed so that its temperature increases by 5.0C. How much heat was transferred into it? A) 4.5  10⁴ J B) 9.0  10⁴ J C) 1.4  10⁵ J D) 2.0  10⁵ J

Marc attaches a falling 250-kg object with a rope through a pulley to a paddle wheel shaft. He places the system in a well-insulated tank holding 12 kg of water. When the object falls, it causes the paddle wheel to rotate and churn the water. If the object falls a vertical distance of 100 m at constant speed, what is the temperature change of the water? (1 kcal = 4186 J, the specific heat of water is 4186 J/kg ·C, and g = 9.8 m/s²) A) 19,600C B) 4700C C) 4.9C D) 2.3C

An inventor develops a stationary cycling device by which an individual, while pedaling, can convert all of the energy expended into heat for warming water. How much mechanical energy is required to increase the temperature of 300 g of water (enough for 1 cup of coffee) from 30C to 90C? (1 cal = 4.186 J, the specific heat of water is 4186 J/kg ·C) A) 94,000 J B) 75,000 J C) 5400 J D) 14 J

An inventor develops a stationary cycling device by which an individual, while pedaling, can convert all of the energy expended into heat for warming water. What minimum power must be generated if 300 g of water (enough for 1 cup of coffee) is to be heated in 10 min from 30C to 90C? (1 cal = 4.186 J, the specific heat of water is 4 186 J/kg ·C) A) 9400 W B) 590 W C) 160 W D) 130 W

A 3.00 g lead bullet is traveling at a speed of 300 m/s when it embeds in a wood post. If we assume that half of the resultant heat energy generated remains with the bullet, what is the increase in temperature of the embedded bullet? (specific heat of lead = 0.0305 kcal/kg·C, 1 kcal = 4186 J) A) 113C B) 137C C) 176C D) 259C

A swimming pool heater has to be able to raise the temperature of the 30,000 gallons of water in the pool by 10.0C. How many kilowatt-hours of energy are required? (One gallon of water has a mass of approximately 3.79 kg and the specific heat of water is 4186 J/kg ·C.) A) 1960 kWh B) 1320 kWh C) 1130 kWh D) 216 kWh

A solar heated house loses about 7.4  10⁷ cal through its outer surfaces on a typical 24-hour winter day. What mass of storage rock is needed to provide this amount of heat if it is brought up to initial temperature of 62C by the solar collectors, and the house is maintained at 20C? (Specific heat of rock is 0.21 cal/g ·C.) A) 160 kg B) 1200 kg C) 6100 kg D) 8400 kg

A 0.2-kg aluminum plate, initially at 20C, slides down a 10-m long surface, inclined at a 30 angle to the horizontal. The force of kinetic friction exactly balances the component of gravity down the plane so that the plate, once started, glides down at constant velocity. If 90% of the mechanical energy of the system is absorbed by the aluminum, what is its temperature increase at the bottom of the incline? (Specific heat for aluminum is 900 J/kg ·C.) A) 0.16C B) 0.07C C) 0.05C D) 0.03C

A waterfall is 70 m high. What is the increase in water temperature at the bottom of the falls if all the initial potential energy goes into heating the water? (g = 9.8 m/s², c_w = 4186 J/kg·C) A) 0.16C B) 0.34C C) 0.69C D) 1.04C

What is the temperature increase of 3.0 kg of water when heated by an 800-W immersion heater for 10 min? (c_w = 4186 J/kg ·C) A) 56C B) 38C C) 29C D) 14C

A solar heating system has a 25.0% conversion efficiency; the solar radiation incident on the panels is 1000 W/m². What is the increase in temperature of 40.0-kg of water in a 1.00-h period by a 4.00 m² area collector? (c_w = 4186 J/kg ·C) A) 14.3C B) 21.5C C) 28.7C D) 44.3C

A machine gear consists of 0.40 kg of iron and 0.16 kg of copper. How much total heat is generated in the part if its temperature increases by 35C? (Specific heats of iron and copper are 450 and 390 J/kg ·C, respectively.) A) 910 J B) 8500 J C) 4000 J D) 5300 J

If a 2100-kg car was moving at 30 m/s, what would be its kinetic energy expressed in the unusual (for kinetic energy) units of calories? (1 cal = 4.186 J) A) 3.0  10⁴ B) 2.3  10⁵ C) 3.8  10⁶ D) 1.1  10⁵

A piece of copper of mass 100 g is being drilled through with a ¹/₂" electric drill. The drill operates at 50.0 W and takes 30.0 s to bore through the copper. If all the energy from the drill heats the copper, find the copper's increase in temperature. (c_copper = 387 J/kg ·C.) A) 40.6C B) 38.8C C) 31.0C D) 27.3C

A slice of bread contains about 90 kcal. If specific heat of a person were 1.00 kcal/kg·C, by how many C would the temperature of a 70.0-kg person increase if all the energy in the bread were converted to heat? A) 2.25C B) 1.86C C) 1.43C D) 1.29C

A hot (70C) lump of metal has a mass of 250 g and a specific heat of 0.25 cal/g·C. John drops the metal into a 500-g calorimeter containing 40 g of water at 20C. The calorimeter is constructed of a material that has a specific heat of 0.10 cal/ g·C. When equilibrium is reached, what will be the final temperature? (c_water = 1.00 cal/g·C.) A) 114C B) 72C C) 40C D) 37C

An 100-g piece of copper, initially at 295C, is dropped into 250 g of water contained in a 300-g aluminum calorimeter; the water and calorimeter are initially at 10.0C. What is the final temperature of the system? (Specific heats of copper and aluminum are 0.0920 and 0.215 cal/g·C, respectively. c_w = 1.00 cal/g·C) A) 12.8C B) 16.5C C) 18.1C D) 32.1C

A 100-g block of copper is taken from a kiln and quickly placed into a beaker of negligible heat capacity containing 300 g of water. The water temperature rises from 15C to 40C. Given c_Cu = 0.10 cal/g·C, and c_water = 1.00 cal/g·C, what was the temperature of the kiln? A) 500C B) 635C C) 790C D) 535C

Find the final equilibrium temperature when 20.0 g of milk at 10.0C is added to 160 g of coffee at 90.0C. (Assume the specific heats of coffee and milk are the same as water and neglect the heat capacity of the container, and c_water = 1.00 cal/g·C = 4186 J/kg·C) A) 85.3C B) 81.1C C) 71.4C D) 66.7C

Twenty grams of a solid at 70C is place in 100 grams of a fluid at 20C. Thermal equilibrium is reached at 30C. The specific heat of the solid: A) is equal to that of the fluid. B) is less than that of the fluid. C) is more than that of the fluid. D) cannot be compared to that of a material in a different phase.

Which of the following best describes a substance in which the temperature remains constant while at the same time it is experiencing an inward heat flow? A) gas B) liquid C) solid D) substance undergoing a change of state

A 0.0030-kg lead bullet is traveling at a speed of 300 m/s when it embeds in a block of ice at 0C. If all the heat generated goes into melting ice, what quantity of ice is melted? (L_f = 80 kcal/kg, the specific heat of lead = 0.03 kcal/kg·C, and 1 kcal = 4186 J) A) 1.47  10^2 kg B) 4.0  10^4 kg C) 3.2  10^3 kg D) 2.6  10^4 kg

A puddle holds 150 g of water. If 0.75 g of water evaporates from the surface, what is the approximate temperature change of the remaining water? (L_v = 540 cal/g) A) -2.7C B) +2.7C C) 0.27C D) +0.27C

Iced tea is made by adding ice to 3.0 kg of hot tea, initially at 80C. How many kg of ice, initially at 0C, are required to bring the mixture to 10C? (L_f = 3.33 x 10⁵ J/kg, c_w = 4186 J/kg·C) A) 2.8 kg B) 1.6 kg C) 1.4 kg D) 2.3 kg

A 50-g cube of ice, initially at 0.0C, is dropped into 200 g of water in an 80-g aluminum container, both initially at 40C. What is the final equilibrium temperature? (Specific heat for aluminum is 900 J/kg·C, the specific heat of water is 4186 J/kg·C, and L_f = 3.33  10⁵ J/kg.) A) 17.6C B) 9.5C C) 12.1C D) 20.6C

In cloud formation, water vapor turns into water droplets which get bigger and bigger until it rains. This will cause the temperature of the air in the clouds to: A) get warmer. B) get cooler. C) will not affect the temperature of the air in the clouds. D) There is no air in clouds.

I take 2.0 kg of ice and dump it into 1.0 kg of water and, when equilibrium is reached, I have 3.0 kg of ice at 0C. The water was originally at 0C. The specific heat of water = 1.00 kcal/kg·C, the specific heat of ice = 0.50 kcal/kg·C, and the latent heat of fusion of water is 80 kcal/kg. The original temperature of the ice was: A) one or two degrees below 0C. B) 80C. C) 120C. D) The whole experiment is impossible.

How much heat energy is required to vaporize a 1.0-g ice cube at 0C? The heat of fusion of ice is 80 cal/g. The heat of vaporization of water is 540 cal/g, and c_water = 1.00 cal/g·C. A) 620 cal B) 720 cal C) 820 cal D) 1 kcal

How much heat energy must be removed from 150 g of oxygen at 22C to liquefy it at 183C? (The specific heat of oxygen gas is 0.218 cal/g·C, and its heat of vaporization is 50.9 cal/g.) A) 14,300 cal B) 9560 cal C) 4320 cal D) 2160 cal

A 6-g lead bullet traveling in 20C air at 300 m/s strikes a flat steel plate and stops. What is the final temperature of the lead bullet? (Assume the bullet retains all heat.) The melting point of lead is 327C. The specific heat of lead is 0.128 J/g·C. The heat of fusion of lead is 24.5 J/g. A) 227C B) 260C C) 293C D) 327C

Which of the following involves the greatest heat transfer? A) One gram of steam at 100C changing to water at 100C. B) One gram of ice at 0C changing to water at 0C. C) One gram of water cooling from 100C to 0C. D) One gram of ice heating from 100C to 0C.

Which of the following has the highest specific heat? A) ice B) water C) steam D) They are all water, so they all have the same specific heat.

When heating 2 kg of ice from , 2 kg of water from , and 2 kg of steam from , which requires the most energy? A) the ice B) the water C) The steam, it's obvious since it is the hottest. D) All three take the same amount.

In typical calorimetry problems, what is the usual conservation law being used? A) energy B) heat C) temperature D) None since nothing is being conserved.

Metal lids on glass jars can often be loosened by running them under hot water. Why is this? A) The hot water is a lubricant. B) The metal and glass expand due to the heating, and the glass being of smaller radius expands less than the metal. C) The metal has a higher coefficient of thermal expansion than glass so the metal expands more than the glass, thus loosening the connection. D) This is just folklore.

The zeroth law of thermodynamics pertains to what relational condition that may exist between two systems? A) zero net forces B) zero velocities C) zero temperature D) thermal equilibrium

A steel wire, 100 m long at 10C, has a coefficient of linear expansion of 11  10^6/C. Give its change in length as the temperature changes from 10C to 45C. A) 0.65 cm B) 3.8 cm C) 5.8 cm D) 12 cm

A rectangular steel plate with dimensions of 60 cm  25 cm is heated from 20C to 150C. What is its change in area? (Coefficient of linear expansion for steel is 11  10^6/C.) A) 0.82 cm² B) 1.1 cm² C) 4.3 cm² D) 6.6 cm²

What happens to a given mass of water as it is cooled from 4C to zero? A) expands B) contracts C) vaporizes D) Neither expands, contracts, nor vaporizes.

The observation that materials expand in size with an increase in temperature can be applied to what proportion of existing substances? A) 100% B) most C) few D) none

A steel plate has a hole drilled through it. The plate is put into a furnace and heated. What happens to the size of the inside diameter of a hole as its temperature increases? A) increases B) decreases C) remains constant D) becomes elliptical

A brass cube, 10 cm on a side, is raised in temperature by 150C. The coefficient of volume expansion of brass is 57  10^6/C. By what percentage does volume increase? A) 12% B) 2.8% C) 1.1% D) 0.86%

A brass cube, 10 cm on a side, is raised in temperature by 150C. The coefficient of volume expansion of brass is 57  10^6/C. By what percentage is any one of the 10-cm edges increased in length? A) 4% B) 2.8% C) 0.38% D) 0.29%

An automobile gas tank is filled to its capacity of 20.00 gallons with the gasoline at an initial temperature of 10C. The automobile is parked in the Sun causing the gasoline's temperature to rise to 60C. If the coefficient of volume expansion for gasoline is 9.6  10^4/C, what volume runs out the overflow tube? Assume the change in volume of the tank is negligible. A) 1.74 gallons B) 0.96 gallon C) 0.72 gallon D) 0.30 gallon

What happens to a given volume of water when heated from 0C to 4C? A) density increases B) density decreases C) density remains constant D) vaporizes

What happens to a volume of water when its temperature is reduced from 8C to 4C? A) density increases B) density decreases C) density remains constant D) vaporizes

The thermal expansion of a solid is caused by: A) the breaking of bonds between atoms. B) increasing the amplitude of the atoms' vibration. C) increasing the distance between equilibrium positions for the vibrating atoms. D) all of the above.

A steel sphere sits on top of an aluminum ring. The steel sphere ( = 1.10  10^5/C) has a diameter of 4.0000 cm at 0C. The aluminum ring ( = 2.40  10^5/C) has an inside diameter of 3.9900 cm at 0C. Closest to which temperature given will the sphere just fall through the ring? A) 462C B) 193C C) 116C D) 57.7C

Between 0C and 4C, the volume coefficient of expansion for water: A) is positive. B) is zero. C) is becoming less dense. D) is negative.

A long steel beam has a length of fifty meters on a cold day when the temperature is 0C. What is the length of the beam on a hot day when T = 40C? (_steel= 1.1  10^5/C) A) 50.044 m B) 50.022 m C) 50.088 m D) 50.0044 m

Suppose the ends of a 20-m long steel beam are rigidly clamped at 0C to prevent expansion. The rail has a cross-sectional area of 15 cm². What force does the beam exert when it is heated to 40C? (_steel = 1.1  10^5/C, Y_steel = 2.0  10¹¹ N/m²) A) 2.6  10⁵ N B) 5.6  10⁴ N C) 1.3  10⁵ N D) 6.5  10² N

At 20C an aluminum ring has an inner diameter of 5.000 cm, and a brass rod has a diameter of 5.020 cm. Keeping the brass rod at 20°C, which of the following temperatures of the ring will allow the ring to just slip over the brass rod? (_Al = 2.4  10^5 /C, _brass = 1.9  10^5/C ) A) 111C B) 187C C) 228C D) 437C

As a copper wire is heated, its length increases by 0.200%. What is the change of the temperature of the wire? (_Cu = 16.6  10^6/C) A) 120C B) 60.2C C) 30.1C D) 6.0C

At room temperature, the coefficient of linear expansion for Pyrex glass is _____ that for ordinary glass. A) the same as B) more than C) less than D) stronger than

A pipe of length 10.0 m increases in length by 2.0 cm when its temperature is increased by 90F. What is its coefficient of linear expansion? A) 22  10^-6/C B) 17  10^-6/C C) 13  10^-6/C D) 40  10^-6/C

What happens to its moment of inertia when a steel disk is heated? A) It increases. B) It decreases. C) It stays the same. D) It increases for half the temperature increase and then decreases for the rest of the temperature increase.

A 2.00-kg copper rod is 40.00 cm long at 23°C. If 50,000 J are transferred to the rod by heat, what is its change in length? (c_copper = 387 J/kg·°C and _copper = 17  10^-6/°C) A) 0.022 cm B) 0.044 cm C) 0.055 cm D) More information is needed.

In the text there is a table of coefficients of linear ( ) and volume ( ) expansions due to temperature changes. For the solid materials in this list, there is a relationship between and which allows you to find the value of if you know . Which of the following best describes that relationship? A) B) C) D)

A steel piano string is attached, under tension, at each end to secure posts. When gently struck, a faint note can be detected coming from the string. The string is then cooled by blowing cold air over it and then is struck again. How does the note now detected compare to the previous one. A) It is the same since the posts don't move. B) It is at a higher frequency than the original one. C) It is at a lower frequency than the original one. D) More than one answer is correct.

Inside a house, stepping on a tile floor barefooted may feel almost cold, but stepping on carpet in an adjacent room feels comfortably warm. Why is this? A) It's because the tile is below room temperature while the carpet is at room temperature. B) It's because the tile is at room temperature while carpet is normally warmer. C) It's because the thermal conductivity of tile is less than that of carpet. D) It's because the thermal conductivity of carpet is less than that of tile.

The inside of a house is at 20C on an early morning when the temperature outside is 15C. The next morning the inside temperature is the same, but the outside temperature is now 5C. How much does the energy per unit time lost by conduction through the walls, windows, doors, etc., change for the house from the first morning to the second one. A) Since the inside temperature stays the same, the loss is the same both days. B) The loss reduces to 1/3. C) The loss triples. D) The loss increases by 5/278 since we need to use the Kelvin scale for this calculation.

Of the following systems, which contains the most heat? A) 100 kg of water at 80°C B) 250 kg of water at 40°C C) 600 kg of ice at 0°C D) Systems do not contain heat.

Carly places one end of a steel bar in a Bunsen flame and the other end in an ice cube. By what factor is the rate of heat flow changed when the bar's cross-sectional area is tripled? A) 0.33 B) 1/9 C) 3.0 D) 9.0

Dmitri places one end of a copper rod in a heat reservoir and the other end in a heat sink. By what factor is the rate of heat flow changed when the temperature difference between the reservoir and sink is doubled? A) 2.0 B) 1/2 C) 4.0 D) 1/4

When a wool blanket is used to keep warm, what is the primary insulating material? A) wool B) air C) the trim around the edge of the blanket D) a thin layer of aluminum foil (usually not apparent) inside the blanket

The use of fiberglass insulation in the outer walls of a building is intended to minimize heat transfer through the wall by what process? A) conduction B) radiation C) convection D) vaporization

If cooking is done using an aluminum pan over an electric burner, which of the following will not promote the rate of heat flow from burner to food? A) increase pan bottom thickness B) increase pan bottom area C) increase burner temperature D) decrease height of pan sides

A windowpane is half a centimeter thick and has an area of 2.0 m². The temperature difference between the inside and outside surfaces of the pane is 15C. What is the rate of heat flow through this window? (Thermal conductivity for this glass is 0.84 W / m ·C.) A) 5000 J/s B) 2500 J/s C) 1300 J/s D) 630 J/s

A 2.0-m² Thermopane window is constructed, using two layers of glass 4.0 mm thick, separated by an air space of 5.0 mm. If the temperature difference is 20C from the inside of the house to the outside air, what is the rate of heat flow through this window? (Thermal conductivity for glass is 0.84 W / m ·C and for air 0.0234 W / m ·C.) A) 7700 W B) 90 W C) 180 W D) 550 W

The thermal conductivity of aluminum is 238 W / m ·C and of copper is 397 W / m ·C. A rod of each material is used as a heat conductor. If the rods have the same geometry and are used between the same temperature differences for the same time interval, what is the ratio of the heat transferred by the aluminum to the heat transferred by the copper? A) 0.599 B) 1.67 C) 0.359 D) 2.78

I place a 250-g ice cube (initially at 0C) in a Styrofoam box with wall thickness 1.0 cm and total surface area 600 cm². If the air surrounding the box is at 20C and after 2 hours the ice is completely melted, what is the conductivity of the Styrofoam material? (L_f = 80 cal/g) A) 9.6  10^5 B) 2.8  10^6 C) 1.15  10^2 D) 2.3  10^4

A silver bar of length 30 cm and cross-sectional area 2.0 cm² is used to transfer heat from a 100C reservoir to a 0C block of ice. How much ice is melted per second? (For silver, k = 427 W /m ·C. For ice, L_f = 334,000 J/kg.) A) 4.2 g/s B) 0.085 g/s C) 0.80 g/s D) 0.043 g/s

A metal bar is used to conduct heat. When the temperature at one end is 100C and at the other is 20C, heat is transferred at a rate of 16 J/s. If the temperature of the hotter end is reduced to 60C, what will be the rate of heat transfer? A) 4 J/s B) 8 J/s C) 9 J/s D) 12 J/s

A metal bar is used to conduct heat. When the temperature at one end is 100C and at the other is 20C, heat is transferred at a rate of 32 J/s. The bar is then stretched uniformly to twice its original length. If again it has ends at 100C and 20C, at what rate will heat be transferred between it ends? A) 4 J/s B) 8 J/s C) 16 J/s D) 32 J/s

Two windowpanes are being compared for their heat conduction. The second windowpane has twice the width, twice the height, and twice the thickness of glass of the first windowpane.How would the heat flow through the second windowpane compare to that of the first. A) They both would have the same amount. B) The second one would have double that of the first. C) The second one would have quadruple that of the first. D) The second one would have eight times that of the first.

Which one of the following processes of heat transfer requires the presence of a fluid? A) conduction B) radiation C) convection D) None of the choices are valid.

Suppose working outside on a hot day someone generate 450 J of heat each second. If this energy is compensated for by the evaporation of sweat, how much water would be lost in an hour? The latent heat of fusion for water is 334 kJ/kg and for vaporization is 2,200 kJ/kg. A) 4.85 liter B) 0.74 liter C) 0.50 liter D) 1.5 liter

Two stars, A and B, have the same emissivity, but the radii and surface temperatures are different with R_A = 2 R_B, and T_A = 0.5 T_B. Assuming the temperature of space to be negligible, which star radiates the most energy per unit time? A) Star A B) Star B C) Both radiate the same amount of energy per unit time. D) More information is needed in order to make a determination.

If one's hands are being warmed by holding them to one side of a flame, the predominant form of heat transfer is what process? A) conduction B) radiation C) convection D) vaporization

The surfaces of a Dewar flask are silvered for the purpose of minimizing heat transfer by what process? A) conduction B) radiation C) convection D) vaporization

How does the heat energy from the Sun reach us through the vacuum of space? A) conduction B) radiation C) convection D) none of the above choices are valid

The filament temperature of a light bulb is 2000 K when the bulb delivers 50 W of power. If its emissivity remains constant, what power is delivered when the filament temperature is 2500 K? A) 122 W B) 62 W C) 98 W D) 50 W

The emissivity of an ideal reflector has which of the following values? A) 0 B) 1 C) 100 D) infinity

Which type of heating causes sunburn? A) conduction B) convection C) radiation D) all of the above

In winter, light-colored clothes will keep you warmer than dark-colored clothes if: A) you are warmer than your surroundings. B) you are at the same temperature as your surroundings. C) you are cooler than your surroundings. D) you are standing in sunlight.

At high noon, the Sun delivers 900 W to each square meter of a blacktop road. What is the equilibrium temperature of the asphalt, assuming its emissivity e = 1? ( = 5.67  10^8 W/m²K⁴) . A) 75C B) 82C C) 91C D) 99C

The surface of the Sun has a temperature of about 5800 K. If the radius of the Sun is 7  10⁸ m, determine the power output of the sun. (Take e = 1, and  = 5.67  10^8 W/m² ·K⁴). A) 3.95  10²⁶ W B) 5.17  10²⁷ W C) 9.62  10²⁸ W D) 6.96  10³⁰ W

The tungsten filament of a light bulb has an operating temperature of about 2100 K. If the emitting area of the filament is 0.80 cm², and its emissivity is 0.68, what is the power output of the light bulb? ( = 5.67  10^8 W/m² ·K⁴) A) 100 W B) 75 W C) 60 W D) 40 W

An object at 27C has its temperature increased to 47C. The power then radiated by this object increases by how many percent? A) 3.3 B) 14 C) 29 D) 253

What temperature increase is necessary to increase the power radiated from an object by a factor of 16? A) 8 K B) 2 K C) 100% D) about 68%

In a greenhouse, electromagnetic energy in the form of visible light enters the glass panes and is absorbed and then reradiated. What happens to this reradiated electromagnetic radiation from within the greenhouse? A) 100% returns to the atmosphere. B) It's partially blocked by glass. C) It's transformed into ultraviolet upon striking the glass. D) It's reflected as visible light upon striking the glass.

Carbon dioxide and water molecules in the atmosphere will absorb: A) infrared light. B) visible light. C) ultraviolet light. D) radio waves.

If the surface temperature of the Earth is and that of the Sun is 6000 K, assuming the same emissivities, what is the ratio of the energy radiated per square meter of the Earth to that of the Sun? A) 0.48 B) C) D)

The Sun is a slightly variable star. What if the surface temperature of the Sun were to increase from 6000 K to 6100 K, what would be the increase in total power radiated assuming no other changes such as radius or emissivity? A) 1.6% B) 6.8% C) 3.4% D) 14%