Physics and Human Affairs Exam 2 UARK
|Questions and Answers
A physics professor pushes against a stationary wall, "working" up a sweat. Is
he doing any actual physical work on the wall?
A) No--it's a law of nature that physics profs never do any actual work.
B) No, because the force by his hands against the wall is balanced by the
force by the wall pushing back.
C) No, because the wall is not moving.
D)Yes, because his arm muscles are moving other muscles through a
distance.
E) Yes, because he is exerting a force against the wall during a period of
time. - -C)
- Under what condition can a force act on an object and yet do no work on
that object?
A) If the object moves with no acceleration.
B) If the force operates at constant (unchanging) power.
C) If the net force on the object is zero.
D) If the object does not move.
E) Nonsense--any force on an object must do work on that object. - -D)
- According to the second law of thermodynamics,
A) kinetic energy cannot be entirely converted into thermal energy.
B) work cannot be entirely converted into thermal energy.
C) the entropy of all the participants in any physical process cannot
decrease.
D) the entropy of all the participants in any physical process cannot increase.
E) the amount of energy going into any thermodynamic process must equal
the amount coming out of that process. - -C)
- In order to quadruple an object's kinetic energy, we must
A) stretch it twice as far.
B) double its height
C) quadruple its speed.
D) quadruple its height.
E) double its speed. - -E)
- Which of the following is a unit of energy?
A) newton/second
B) Calorie
C) newton
D) watt
E) None of the above. - -B)
, - What form or forms of energy does a falling elastic ball have just before it
is dropped from some height above the floor [see figure above]?
A) Elastic only
B) Kinetic only
C) Kinetic and gravitational
D) Gravitational only
E) Kinetic and gravitational and elastic - -D)
- The "energy efficiency" of a device is
A) its thermal energy output divided by the total energy put into the device.
B) its useful energy output divided by the total energy put into the device.
C) the total energy put into the device divided by its thermal energy output.
D) the total energy put into the device divided by its useful energy output.
E) its total energy output divided by the total energy put into the device. - -
B)
- Is a fuel-cell vehicle properly described as a "heat engine"?
A) No, because it converts chemical energy directly to electric energy.
B) Yes, because it uses chemical energy to create electric energy.
C) Yes, because it uses thermal energy to produce electricity.
D) No, because it converts electric energy directly into chemical energy.
E) Yes, because it uses thermal energy to do work. - -A)
- How much work do you do when you lift a 3 N apple by 2 m during a time
of 6 s?
A) 18 J
B) 12 J
C) 6 J
D) 1.5 J
E) 1 J - -C)
- The power of American automobiles is usually rated in "horsepower." What
other units could be used?
A) Calories
B) joules
C) watts
D) None of the above.
E) All of the above. - -C)
- If you run a 3000-watt hair dryer for 30 minutes, how much electric energy
do you consume?
A) 6 kW ∙ h
B) 90,000 kW ∙ h
C) 100 kW ∙ h
D) 1.5 kW ∙ h
, E) None of the above. - -D)
- The figure above shows a marble rolling freely back and forth along a
curved track. The track is positioned vertically. At position A its gravitational
energy is
A) less than its gravitational energy at B.
B) greater than its gravitational energy at B.
C) the same as its gravitational energy at B. - -B)
- To what two quantities is work proportional?
A) acceleration and distance
B) force and speed
C) force and distance
D) energy and distance
E) power and distance - -C)
- Since 1 kilowatt equals 1000 watts, and 1 hour equals 3600 seconds, it
follows that the kilowatt-hour is
A) an energy of 3.6 million watts.
B) a power of 3.6 million watts.
C) an energy of 3.6 million joules.
D) a power of 3.6 million joules.
E) None of the above. - -C)
- Which of the following is an example of chemical energy?
A) the energy stored in firewood that has been gathered for burning
B) the energy stored in your body, that enables you to do work
C) Both of the above.
D) the energy in hot steam
E) the energy in a stretched rubber band - -C)
- The "law of heat engines" is one form of
A) the law of inertia.
B) the second law of thermodynamics.
C) idiocy.
D) the law of conservation of energy.
E) the ideal gas laws. - -B)
- Chemical energy is transformed into gravitational energy when
A) a leaf undergoes photosynthesis.
B) a car accelerates.
C) a block slides downhill.
D) a person walks uphill.
E) water evaporates. - -D)
- A block of wood slides to a stop along a tabletop. In this process,
|Questions and Answers
A physics professor pushes against a stationary wall, "working" up a sweat. Is
he doing any actual physical work on the wall?
A) No--it's a law of nature that physics profs never do any actual work.
B) No, because the force by his hands against the wall is balanced by the
force by the wall pushing back.
C) No, because the wall is not moving.
D)Yes, because his arm muscles are moving other muscles through a
distance.
E) Yes, because he is exerting a force against the wall during a period of
time. - -C)
- Under what condition can a force act on an object and yet do no work on
that object?
A) If the object moves with no acceleration.
B) If the force operates at constant (unchanging) power.
C) If the net force on the object is zero.
D) If the object does not move.
E) Nonsense--any force on an object must do work on that object. - -D)
- According to the second law of thermodynamics,
A) kinetic energy cannot be entirely converted into thermal energy.
B) work cannot be entirely converted into thermal energy.
C) the entropy of all the participants in any physical process cannot
decrease.
D) the entropy of all the participants in any physical process cannot increase.
E) the amount of energy going into any thermodynamic process must equal
the amount coming out of that process. - -C)
- In order to quadruple an object's kinetic energy, we must
A) stretch it twice as far.
B) double its height
C) quadruple its speed.
D) quadruple its height.
E) double its speed. - -E)
- Which of the following is a unit of energy?
A) newton/second
B) Calorie
C) newton
D) watt
E) None of the above. - -B)
, - What form or forms of energy does a falling elastic ball have just before it
is dropped from some height above the floor [see figure above]?
A) Elastic only
B) Kinetic only
C) Kinetic and gravitational
D) Gravitational only
E) Kinetic and gravitational and elastic - -D)
- The "energy efficiency" of a device is
A) its thermal energy output divided by the total energy put into the device.
B) its useful energy output divided by the total energy put into the device.
C) the total energy put into the device divided by its thermal energy output.
D) the total energy put into the device divided by its useful energy output.
E) its total energy output divided by the total energy put into the device. - -
B)
- Is a fuel-cell vehicle properly described as a "heat engine"?
A) No, because it converts chemical energy directly to electric energy.
B) Yes, because it uses chemical energy to create electric energy.
C) Yes, because it uses thermal energy to produce electricity.
D) No, because it converts electric energy directly into chemical energy.
E) Yes, because it uses thermal energy to do work. - -A)
- How much work do you do when you lift a 3 N apple by 2 m during a time
of 6 s?
A) 18 J
B) 12 J
C) 6 J
D) 1.5 J
E) 1 J - -C)
- The power of American automobiles is usually rated in "horsepower." What
other units could be used?
A) Calories
B) joules
C) watts
D) None of the above.
E) All of the above. - -C)
- If you run a 3000-watt hair dryer for 30 minutes, how much electric energy
do you consume?
A) 6 kW ∙ h
B) 90,000 kW ∙ h
C) 100 kW ∙ h
D) 1.5 kW ∙ h
, E) None of the above. - -D)
- The figure above shows a marble rolling freely back and forth along a
curved track. The track is positioned vertically. At position A its gravitational
energy is
A) less than its gravitational energy at B.
B) greater than its gravitational energy at B.
C) the same as its gravitational energy at B. - -B)
- To what two quantities is work proportional?
A) acceleration and distance
B) force and speed
C) force and distance
D) energy and distance
E) power and distance - -C)
- Since 1 kilowatt equals 1000 watts, and 1 hour equals 3600 seconds, it
follows that the kilowatt-hour is
A) an energy of 3.6 million watts.
B) a power of 3.6 million watts.
C) an energy of 3.6 million joules.
D) a power of 3.6 million joules.
E) None of the above. - -C)
- Which of the following is an example of chemical energy?
A) the energy stored in firewood that has been gathered for burning
B) the energy stored in your body, that enables you to do work
C) Both of the above.
D) the energy in hot steam
E) the energy in a stretched rubber band - -C)
- The "law of heat engines" is one form of
A) the law of inertia.
B) the second law of thermodynamics.
C) idiocy.
D) the law of conservation of energy.
E) the ideal gas laws. - -B)
- Chemical energy is transformed into gravitational energy when
A) a leaf undergoes photosynthesis.
B) a car accelerates.
C) a block slides downhill.
D) a person walks uphill.
E) water evaporates. - -D)
- A block of wood slides to a stop along a tabletop. In this process,
