Physics 115 Mastering Physics Exam Questions And
Complete Answers
In the video, the temperature of the gas inside the fire piston increased because - ANSWER
Work was done on the gas when the plunger was depressed.
Which physical law underlies the first law of thermodynamics? - ANSWER conservation of
energy
When the quantity Q is greater than zero, __________ is added to the system. - ANSWER heat
When the quantity W in the first law is greater than zero, it refers to the __________. - ANSWER
work done on the system
The quantity ΔEth in the first law of thermodynamics is the change in the __________ of the
system. - ANSWER thermal energy
If heat is added to a system (Q>0) and no change in thermal energy of the system occurs (Δ
Eth=0), then the system must do __________ work on the outside world. - ANSWER positive
The second law of thermodynamics imposes what limit on the efficiency of a heat engine? -
ANSWER A heat engine must deposit some energy into a cold reservoir
,A refrigerator is an example of a __________. - ANSWER heat pump
If we assume a typical efficiency for the body, as quoted in the video, how much energy input
would it take to climb a ladder, increasing your body's potential energy by 5,000 J? - ANSWER
20,000 J
A typical efficiency of the human body is about _____. - ANSWER 25%
A machine uses 1000 J of electric energy to raise a heavy mass, increasing its potential energy
by 300 J. What is the efficiency of this process? - ANSWER 30%
The entropy of an isolated system _________. - ANSWER either increases or remains constant
In the video, we use the atomic model to describe pressure as resulting from - ANSWER The
force from the collision of gas molecules with the walls of their container
An atom's atomic mass number is the number of its ______. - ANSWER protons + neutrons
The three different gas-law processes described in this video are - ANSWER Constant volume,
constant pressure, and constant temperature.
A sample of nitrogen gas is inside a sealed container. The container is slowly compressed,
while the temperature is kept constant. This is a(n) ________ process - ANSWER isothermal
, A sample of nitrogen gas is in a sealed container with a constant volume. Heat is added to the
gas. The pressure __________ - ANSWER increases
When the temperature of an ideal gas is increased, which of the following also increases? -
ANSWER the average kinetic energy of the gas atoms
Which type of heat transfer can happen through empty space? - ANSWER radiation
Heat is added to each block at the same constant rate until it reaches a temperature of 500 K.
Which of the following statements is true? - ANSWER The iron takes less time than the
aluminum to reach the final temperature.
When the two materials have reached thermal equilibrium, the block of aluminum is cut in
half and equal quantities of heat are added to the iron block and to each portion of the
aluminum block. Which of the following statements is true? - ANSWER The blocks remain in
thermal equilibrium.
Due to concerns about the toxic properties of mercury, many thermometers are made with
other liquids. Consider draining the mercury from the above thermometer and replacing it
with another, such as alcohol. Alcohol has a coefficient of volume expansion 5.6 times greater
than that of mercury. The amount of alcohol is adjusted such that when placed in ice water,
the thermometer accurately records 0∘C . No other changes are made to the thermometer.
When the alcohol thermometer is placed in 20∘C water, what temperature will the
thermometer record? - ANSWER greater than 20∘C
Complete Answers
In the video, the temperature of the gas inside the fire piston increased because - ANSWER
Work was done on the gas when the plunger was depressed.
Which physical law underlies the first law of thermodynamics? - ANSWER conservation of
energy
When the quantity Q is greater than zero, __________ is added to the system. - ANSWER heat
When the quantity W in the first law is greater than zero, it refers to the __________. - ANSWER
work done on the system
The quantity ΔEth in the first law of thermodynamics is the change in the __________ of the
system. - ANSWER thermal energy
If heat is added to a system (Q>0) and no change in thermal energy of the system occurs (Δ
Eth=0), then the system must do __________ work on the outside world. - ANSWER positive
The second law of thermodynamics imposes what limit on the efficiency of a heat engine? -
ANSWER A heat engine must deposit some energy into a cold reservoir
,A refrigerator is an example of a __________. - ANSWER heat pump
If we assume a typical efficiency for the body, as quoted in the video, how much energy input
would it take to climb a ladder, increasing your body's potential energy by 5,000 J? - ANSWER
20,000 J
A typical efficiency of the human body is about _____. - ANSWER 25%
A machine uses 1000 J of electric energy to raise a heavy mass, increasing its potential energy
by 300 J. What is the efficiency of this process? - ANSWER 30%
The entropy of an isolated system _________. - ANSWER either increases or remains constant
In the video, we use the atomic model to describe pressure as resulting from - ANSWER The
force from the collision of gas molecules with the walls of their container
An atom's atomic mass number is the number of its ______. - ANSWER protons + neutrons
The three different gas-law processes described in this video are - ANSWER Constant volume,
constant pressure, and constant temperature.
A sample of nitrogen gas is inside a sealed container. The container is slowly compressed,
while the temperature is kept constant. This is a(n) ________ process - ANSWER isothermal
, A sample of nitrogen gas is in a sealed container with a constant volume. Heat is added to the
gas. The pressure __________ - ANSWER increases
When the temperature of an ideal gas is increased, which of the following also increases? -
ANSWER the average kinetic energy of the gas atoms
Which type of heat transfer can happen through empty space? - ANSWER radiation
Heat is added to each block at the same constant rate until it reaches a temperature of 500 K.
Which of the following statements is true? - ANSWER The iron takes less time than the
aluminum to reach the final temperature.
When the two materials have reached thermal equilibrium, the block of aluminum is cut in
half and equal quantities of heat are added to the iron block and to each portion of the
aluminum block. Which of the following statements is true? - ANSWER The blocks remain in
thermal equilibrium.
Due to concerns about the toxic properties of mercury, many thermometers are made with
other liquids. Consider draining the mercury from the above thermometer and replacing it
with another, such as alcohol. Alcohol has a coefficient of volume expansion 5.6 times greater
than that of mercury. The amount of alcohol is adjusted such that when placed in ice water,
the thermometer accurately records 0∘C . No other changes are made to the thermometer.
When the alcohol thermometer is placed in 20∘C water, what temperature will the
thermometer record? - ANSWER greater than 20∘C
