physics thermodynamics unit 6
if two small beakers of water, one at 70 C and one at 80 C, are emptied into a larger beaker what is the final temperature of the water
the final temperature is between 70 C and 80 C
A container of water has its smallest volume at________
4 degrees C
Which of the following expands most when the temperature is lowered
Water at 4 degrees C
which of the following is not a widely used temperature scale
joule
what temperature has the same numerical value on both the Fahrenheit and the Celsius scales
-40.0 degrees
An ideal gas system undergoes an adiabatic process in which it expands and does 20 J of work on its environment. How much energy is transferred to the system as heat?
0 J
When 4 grams of a substance loses 4 calories in cooling 1 C its specific heat capacity using water as the unit of measure is________
1
The ideal efficiemcy for a heat engine operating between temperatures of 2050 K and 310 K is
85%
Mix some 70 degree celsius water with some 40 degree celsius, and you'll get water at
A temperature depending on the masses(or volumes) of water
the use of fiberglass insulation in the outer walls of a building is intended to minimize heat transfer through what process
Conduction
first law of thermodynamics is a restatment of the
Conservation of energy
The greater difference in temp between the input reservoir and output reservoir for a heat engine the
Greater efficiency
According to the second law of thermodynamics which of the following statements about a heat engine operating
Heat from a high-temperature reservoir cannot be completely converted to work
Pull a closed plastic bag of dry air quickly down from a high elevation and the bag of air will become
Hotter
When a volume of air is compressed and no heat enters or leaves, the air temperature will
Increase
Which of the following is a way to improve the efficiency of a heat engine
Increase Qh
Suppose the temperature of the input reservoir in a heat engine doesn't change. As the sink temperature is lowered, the efficiency of the engine
Increases
Is an isovolumertic process for an ideal gas the systems change in the energy as heat is equivalent to change in which of the following
Internal energy
According to the first law of thermodynamics the difference between energy transferred to or from a system as heat and energy transferred to or from a system by working
Internal energy change
What thermodynamic process for an ideal gas system has an unchanging internal energy and a heat intake that corresponds to the value of the work done by the system?
Isothermal
Which thermodynamic process takes place at constant volume so that no work is done on or by the system
Isovolumetric
A thermodynamic process occurs and the entropy of a system decreases. What can be concluded about the entropy chamge of the environment
It increases
A heat engine has taken in energy as heat and used a portion of it to do work. What must happen next for the engine to complete the cycle and return to it initial conditions
It must give up energy as heat to a lower temperature so work can be done on it
A chunk of ice with a mass of 1 kg at 0 C melts and absorbs 3.33 x 10^5J of heat in the process which best describes what happened to this system
Its entropy increased
Imagine you could observe the individual atoms that make up a piece of matter and that you observe the motion of the atoms becoming more orderly. What can you assume about the system?
Its entropy is decreasing
An electrical power plant manages to transfer 88 precent of the heat in thr burning of fossil fuel to convert water to steam. Of the heat carried by the steam, 40% is converted to the mechanical energy of the spinning turbine. Which best describes the overall efficiency of the heat-to-work conversion in the plant
Less than 40%
The fact that desert sand is ver hot in the day and very cold at night is evidence that sand has a __________
Low specific heat capacity
Ceramic automobiles engines that operate at hgiher temps will be
More efficient
Systems that are left alone, tend to move toward a state of
More entropy
how is energy transferred as heat always directed
from an object at high temperature to an object at low temperature
what happens to the internal energy of an ideal gas when it is heated from 0 C to 4 C
it increases
When an iron ring is heated the hole becomes
larger
what three properties of a substance affect amount o energy transferred as heat to or from the substance
mass, temperature change, specific heat capacity
Entropy measures
messiness
which of the following best describes the relationship between two systems in thermal equilibrium
no net energy is exchanged
Entropy is closely related to the
second law of thermodynamics
if energy is transferred from a table to a block of ice moving across the table which of the following statements are true
the ice is cooler than the table
A bimetallic strip will bend when heated because
Each metal expands at different rates
The requirement that a heat a heat engine must give up some energt at a lower temperature in order to do work corresponds to which law of thermodynamics
Second
a calorimeter is used to determine the specific heat capacity of a test metal. if the specific heat capacity of water is known, what quantities must be measured.
metal mass, water mass, initial and final temperatures of metal and water
a slice of bread contains about 4.19 x 10^5 J of energy. If the specific heat capacity of a person is 4.19 x 10^3 j/kg x C, by how many degrees Celsius would the temperature of a 70 kg person increase if all the energy in the brad where converted into heat
1.43 C
A nail is driven into a board with an initial kinetic energy of 150 J. if the potential energy before and after the event is the same, what is the change in the internal energy of the board and nail.
150 J
a substance registers a temperature change from 20 c to 40 c. what incremental temperature change does tho correspond
20 K
80 joules of heat is added to a system that preforms 55 joules of work. The internal energy change of the system is
25 J
A volume of air has a temperature of 0 degrees C an equal volume of air that is twice as hot has a temperature of about
273 degrees C
Air cools as it escapes from a divers compressed ait tank. What kind of process is this?
Adiabatic
Temperature is mostly related to the __________
Average molecular kinetic energy in a substance
The energy content of a piece of food is normally determined by __________
Burning the food
If a volume of air is swept upward with no heat input or output, its temp
Decreases
When work is done by a system and no heat is added to it the temperature of the system
Decreases
How is the conversion of internal energy expressed for a system during an isothermal process
Delta T=0 so delta u=0 therefore delta u= Q-W=0 or Q=W
How is the conversion of internal energy expressed for a system during an isovolumertic process
Delta V=0 so P delta V=0 and W=0 therefor change in u =Q
Two identical blocks of iron one at 10 degrees C and the other at 20 degrees C are put in contact suppose the cooler block cools to 5 degrees C and the warmer block warms to 25 degrees C this would violate
Second law of thermodynamics
When mechanical work is done on a system, there can be an increase in its
Temp and internal energy
Which if the following it true duting a phase change?
Temperature remains constant
Which statement applies when all of the entropy changes in a process are taken into account
The increase in entropy are always greater than the decrease
Whem a drop of ink mixes with water, what happens to the entropy of the system
The systems entropy increases and the total entropy of the universe increases
Which is denser, ice at 0 degrees or water at 4 degrees C
The water
Internal energy is the ___________
Total amount of energy contained in an object
During an isovolumertic process which if the following does not change
Volume
While an ideal gas is doibg postive worj on its surroundings, which of the gas's quantities must br increasing
Volume
Cool a sample of air from zero on the Celsius scale to near zero on the absolute scale and the air loses
Volume and pressure
Which equation describes the net work done for a complete cycle of a heat engine
W net= Qh-Qc
Runnig a refrigerator with it's door open in a hot room makes the room
Warmer
Which has the higher specific heat capacity, water or sand?
Water
Which releases the most energy 100 grams of 100 C water cooling to 50 C or 100 grams of iron at 100 C cooling to 50 C ( the specific heat of iron is 0.12cal/gC
Water
The reason fish live from year to year in ponds that freeze over in the winter is that ______
Water below the ice is 4 degrees above freezing
During a very cold winter, water pipes sometimes burst. The reason for this is _________
Water expands when freezing
Consider a gap cut into a metal ring. If the ring is heated the gap becomes
Wider
in an elastic collision between two ball bearings kinetic energy is conserved. if there is no change in potential energy, which of the following is true.
deltaU=0
if there is no temperature difference between a substance and its surroundings what has occurred on the microscopic level
energy has transferred from higher- energy particles to lower-energy particles
Heat is the
energy transferred between objects because of a temperature difference
which of the following terms describe a transfer of energy
heat
As a system becomes more disordered, entropy
increases
what are the energies associated with atomic motion called
internal energy