Physics Final
A certain metal has a specific heat c = 0.21 cal/goC and a mass m= 25.6 g. The initial temperature is Ti = 34.6oC, and the final temperature Tf = 54.6oC. The quantity of heat absorbed is
+110 cal
A 250-g piece of lead is heated to 100oC and is then placed in a 400-g copper container holding 500 g of water. The specific heat of copper is c = 0.386 kJ/kgK. The container and the water had an initial temperature of 18.0oC. When thermal equilibrium is reached, the final temperature of the system is 19.15oC. If no heat has been lost from the system, what is the specific heat of the lead? (the specific heat of water is 4.180 kJ/kgK)
0.128 kJ/kgK
To raise the temperature of a 2.0-kg piece of metal from 20o to 100oC, 61.8 kJ of heat is added. What is the specific heat of this metal?
0.39 kJ/kgK
When the temperature of an ideal gas is increased from 300 K to 400 K, the average kinetic energy of the gas molecules increases by a factor of
1.33
The internal energy of a monatomic gas is 1.0 J. The temperature of the gas is 298 K. How many particles are there in the gas?
1.6x1020
A lake with 8.0x109 kg of water, which has a specific heat of 4180 J/kgoC, warms from 10o to 15oC. The amount of heat transferred to the lake is
1.7x1014 J
A 3-kg mass of metal of specific heat = 0.1 kcal/kgoC at a temperature of 600oC is dropped into 1.0 kg water at 20oC. With no heat losses to the surroundings, determine the equilibrium temperature of the mixture, and if it is 100oC, calculate what mass of water is turned into steam at this temperature.
100° C and 130 g of steam
The graph shows the temperature of a 75.0-g sample of material as thermal energy is added to it. The material is initially a solid. The pressure remains constant, and there is no chemical change. The latent heat of vaporization is
107 kJ/kg
A 3.00-g lead bullet is traveling at a speed of 240 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 = 128J/kgK)
113° C
A 2.0-kg mass of iron (specific heat = 0.12 kcal/kgoC) at a temperature of 430oC is dropped into 48 kg of water. The water is initially at a temperature of 10oC. With no heat losses to the surroundings, the equilibrium temperature of the iron and water is approximately
12oC
The graph shows the temperature of a 75.0-g sample of material as thermal energy is added to it. The material is initially a solid. The pressure remains constant, and there is no chemical change. The specific heat of the liquid phase is
152 J/kgoC
A 6.0-g lead bullet traveling at 300 m/s penetrates a wooden block and stops. If 50 percent of the initial kinetic energy of the bullet is converted into thermal energy in the bullet, by how much does the bullet's temperature increase? (The specific heat of lead is 128 J/kgK.)
180°C
The temperature gradient in a wall is 80 Cº/cm, and the thermal conductivity of this wall is 4.0x10-3 cal/scmCº. The amount of heat conducted per minute per square centimeter through this wall is approximately
19 cal
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 doubled?
2
The graph shows the Maxwell-Boltzmann distribution function of the number of gas molecules per unit speed range for two different temperatures. Which gas has a higher temperature?
2
The graph shows the Maxwell-Boltzmann distribution function of the number of gas molecules per unit speed range at a given temperature. The average speed, the most probable speed, and the rms speed (in this order) are most likely given by
2, 1, 3
A room measures (3.0 m) x (4.0 m) x (2.0 m) and is at 15°C and normal air pressure (101,325 Pa). When the temperature is increased to 25°C, the number of molecules that escaped from the room is, assuming that the pressure stays at normal air pressure
2.1x1025
Two liquids, A and B, are mixed together. Liquid A has mass m and was initially at temperature 40oC, and liquid B has mass 2m and was initially at temperature 5oC. The specific heat of liquid A is 1.5 times that of liquid B. Calculate the final temperature of the mixture.
20.0oC
960 J = _____ cal.
229
The mean of the squares of the velocity in the x-direction for a gas has the value of 800 m2/s2. What is the value for the mean of the squares of the total velocity?
2400 m2/s2
A long steel beam has a length of twenty-five 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? (asteel = 1.1x10-5/C°)
25.011m
A single atom of Krypton has a mass of 1.39x10-25 kg. The temperature of Krypton gas is 298 K. What is the root mean square velocity of the gas?
298 m/s
What is the temperature increase of 4.0 kg of water when heated by an 800-W immersion heater for 10 min? (cw = 4 186 J/kg°C)
29°
The graph shows the Maxwell-Boltzmann distribution function of the number of gas molecules per unit speed range at a given temperature. The rms speed is most likely given by
3
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 tripled?
3.0
The surface of the Sun has a temperature of about 5,800 K. If the radius of the Sun is 7x108 m, determine the power output of the sun. (Take e = 1, and σ = 5.67x10-8 W/m2×K4).
3.95x1026 W
The highest and lowest temperatures ever recorded in the United States are 134ºF (California, 1913) and -80ºF (Alaska, 1971). What are these temperatures in kelvins?
330 K and 211 K
The mean of the squares of the velocity in the y-direction for a gas has the value of 1200 m2/s2. What is the value for the mean of the squares of the total velocity?
3600 m2/s2
Five molecules of a gas have the following speeds: 200 m/s, 300 m/s, 400 m/s, 500 m/s, and 600 m/s. The rms speed for these molecules is
424 m/s
Five molecules of a gas have the following speeds: 200 m/s, 350 m/s, 400 m/s, 550 m/s, and 600 m/s. The rms speed for these molecules is
444 m/s
A single molecule of Oxygen has a mass of 5.32x10-26 kg. The temperature of Oxygen gas is 298 K. What is the root mean square velocity of the gas?
482 m/s
Inside a sphere of radius 12 cm are 8.0x1023 gas molecules at a temperature of 50.0°C. What pressure do the gas molecules exert on the inside of the sphere?
490 kPa
A temperature difference of 5ºC is the same as a difference of
5 K
A steel wire, 150 m long at 10°C, has a coefficient of linear expansion of 11x10-6 1/oC. Calculate its change in length as the temperature changes from 10°C to 45°C.
5.8 cm
A certain blackbody radiates 100 W at a temperature of 2000 K. How much power would this body radiate at 3000 K?
506 W
The graph shows the temperature of a 75.0-g sample of material as thermal energy is added to it. The material is initially a solid. The pressure remains constant, and there is no chemical change. The latent heat of fusion is
53 kJ/kg
A person is losing thermal energy through the skin at a rate of 120 W when his skin temperature is 30°C. He puts on a sweater, and his skin temperature rises to 33°C. The effective thermal conductivity between his core and the environment changes from 0.22 W/mK to 0.18 W/mK. At what rate is he now losing thermal energy?
56 W
If the rms speed of oxygen molecules is 460 m/s at 0ºC, the rms speed of oxygen molecules at 273ºC is approximately
650 m/s
The tungsten filament of a light bulb has an operating temperature of about 2,100 K. If the emitting area of the filament is 1.0 cm2, and its emissivity is 0.68, what is the power output of the light bulb? (σ = 5.67x10-8 W/m2×K4)
75 W
If a student eats a fast food meal that has 762 food calories, how many heat calories does that equal?
762,000
A small lake has a surface area of 10000 m2. Assuming that the average depth of the lake is 2 m, how much heat is released when the average temperature of the water in the lake drops by 1oC?
8.36x1010 J
2,000 cal = _____ J.
8372
Modern railway tracks consist of continuous welded-steel rails of 1.0-km lengths. If the coefficient of linear expansion of steel is 11x10-6 K-1, by how much would such a rail change in length between the highest summer temperature (40ºC) and the lowest winter temperature (-40ºC)?
88 cm
What is the internal energy of a monatomic gas that has 1.5x1021particles at a temperature of 310 K?
9.6 J
The filament temperature of a light bulb is 2,000 K when the bulb delivers 40 W of power. If its emissivity remains constant, what power is delivered when the filament temperature is 2,500 K?
98 W
The noble gases, listed by increasing molecular weight, are He, Ne, Ar, Kr, Xe, and Rn. If samples of 1 mole each of these gases are placed in separate containers and heated to 300 K, which gas has the greatest internal energy and the molecules of which gas have the highest rms speed?
All the gases have the same internal energy, and the He has the greatest rms speed.
Which of the following statements about thermal contact and thermal equilibrium is NOT true?
For energy to be transferred between two objects they have to be in thermal contact.
The temperature of a quantity of ideal gas in a sealed container is increased from 0°C to 273°C. What happens to the rms speed of the molecules of the gas as a result of this temperature increase?
It increases but it less than doubles.
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 the result be?
It would be between that of copper and that of zinc, depending on coating thickness
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?
It's because the thermal conductivity of carpet is less than that of tile.
The first experiment, which conclusively demonstrated the equivalence of
Joule
Which of the following is an assumption that is made in the kinetic theory of gases?
Molecules make up only a small fraction of the volume occupied by a gas.
Which of the following involves the greatest heat transfer?
One gram of steam at 100°C changing to water at 100°C.
The star Asthtar is the size of our Sun and at a temperature of 6,000 K, while Procyon is ½ the diameter of our Sun but 12,000 K. Which star is more luminous (that is, a higher power output?
Procyon is more luminous
Sea breezes that occur near the shore are attributed to a difference between land and water with respect to what property?
Specific heat
Two stars, A and B, have the same emissivity, but the radii and surface temperatures are different with RA = 0.5 RB, and TA = 2 TB. Assuming the temperature of space to be negligible, which star radiates the most energy per unit time?
Star A
Aluminum has a specific heat more than twice that of copper. Identical masses of aluminum and copper, both at 0oC. There are two identical calorimeters. Both calorimeters contain the same volume of water. Both calorimeters are at the same hot temperature. The aluminum mass is dropped into one calorimeter. The copper mass is dropped into the other calorimeter. Both systems come to equilibrium. Compare the equilibrium temperatures of the two masses.
The copper mass has a higher equilibrium temperature than the aluminum mass.
Heat is added to a substance at a constant rate. The substance starts as a solid and is melted; the liquid is heated and vaporized; finally, the vapor is heated. This process is shown in the graph. Which of the following statements is correct? The latent heat of vaporization is greater than the latent heat of fusion.
The latent heat of vaporization is greater than the latent heat of fusion.
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 10°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?
The loss doubles
Metal lids on glass jars can often be loosened by running them under hot water. Why is this?
The metal has a higher coefficient of thermal expansion than glass so the metal expands more than the glass thus loosening the connection.
Which of the following is NOT an assumption made in the kinetic theory model of a gas?
The range of molecular forces is much greater than the molecular size.
The zeroth law of thermodynamics pertains to what relational condition that may exist between two systems?
Thermal equilibrium
Performed the cannon-boring experiment which showed the weakness of the caloric theory.
Thompson, Count Rumford
In a Maxwell-Boltzmann distribution function of molecular speeds, the rms speed is
always greater than the mean speed
Which one of the following processes of heat transfer requires the presence of a fluid?
convection
If the thickness of a uniform wall is halved, the rate at which heat is conducted through the wall is
doubled.
Consider two different rods. The greatest thermal conductivity will be in the rod with:
electrons that are freer to move from atom to atom.
The specific heat of a substance is a measure of
energy needed to change the kinetic energies of atoms and/or molecules and/or electrons by a temperature increment.
Two types of wall separate a refrigerated room from the rest of a building. Wall 1 has half the thermal conductivity of wall 2. Wall 2 is half as thick as wall 1. The two walls have the same area. The rate of heat flow through wall 2 compared with the rate of heat flow through wall 1 is
four times greater
If the absolute temperature of the filament of a lamp were doubled, the energy radiated per second by the filament would
increase by a factor of 16
If the absolute temperature of the filament of a lamp were doubled, the energy radiated per second by the filament would
increase by a factor of 16.
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?
increase pan bottom thickness
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?
increases
If the temperature on the warmer side of a wall is doubled, the rate at which heat is conducted through the wall
increases but the rate cannot be determined.
If the absolute temperature of a gas is doubled, what is the change in the average kinetic energy of its molecules?
increases by a factor of 2
If the absolute temperature of an object is tripled, the rate at which it radiates thermal energy
increases by a factor of 81
If the absolute temperature of a gas is doubled, what is the change in the rms speed of its molecules?
increases by a factor of sqrt(2)
If a piece of iron is exposed to the sun, its temperature rises until
it loses and gains heat at the same rate.
The oxygen (molar mass = 32 g/mol) and nitrogen (molar mass = 28 g/mol) molecules in this room have equal average
kinetic energies, but the oxygen molecules are slower
The absolute temperature of an ideal gas is directly proportional to which of the following properties, when taken as an average, of the molecules of that gas?
kinetic energy
The temperature of a gas is directly proportional to which of the following properties, when taken as an average, of the molecules of that gas?
kinetic energy
Heat is added to a substance at a constant rate. The substance starts as a solid and is melted; the liquid is heated and vaporized; finally, the vapor is heated. This process is shown in the graph. The latent heat of fusion can be found by
multiplying the length of B (in seconds) by the rate at which heat is added and dividing by the mass of the substance.
Heat is added to a substance at a constant rate. The substance starts as a solid and is melted; the liquid is heated and vaporized; finally, the vapor is heated. This process is shown in the graph. The latent heat of vaporization can be found by
multiplying the length of D (in seconds) by the rate at which heat is added and dividing by the mass of the substance.
When two gases separated by a diathermal wall are in thermal equilibrium with each other:
only their temperature must be the same
How does the heat energy from the sun reach us through the vacuum of space?
radiation
If one's hands are being warmed by holding them to one side of a flame, the predominant form of heat transfer is vaporization convection radiation conduction
radiation
The earth receives approximately 1.7x1017 J of energy from the sun each second through a process called
radiation
The surfaces of a Dewar flask are silvered for the purpose of minimizing heat transfer by what process?
radiation
Which type of heating causes sunburn?
radiation
The main process by which heat is transferred to your home when it is heated by solar energy is
radiation.
John rapidly pulls a plunger out of a cylinder. As the plunger moves away, the gas molecules bouncing elastically off the plunger are:
rebounding at a lower speed than they would have if the plunger weren't removed.
On a sunny day at the beach, the reason the sand gets so hot and the water stays relatively cool is attributed to the difference in which property between water and sand?
specific heat
The zeroth law of thermodynamics allows us to define:
temperature
For an ideal gas of a given mass, if the pressure remains the same and the volume increases:
the average kinetic energy of the molecules increases.
If the temperature of an ideal gas contained in a rigid box is increased:
the average speed of the molecules in the box will be increased.
On a hot summer day, water collects on the outside of a glass of ice lemonade. The water comes from
the condensation of the water vapor due the fact that the glass is much colder than the air.
If two objects are in thermal equilibrium with each other:
they cannot be at different temperatures
If it is known that two bodies are in thermal equilibrium, one can conclude that
they must be at the same temperature.
