Phys exam 2
Power
Electric generating plants are usually rated in "megawatts". This is a unit of
Gravitational forces are always attractive but electrical forces can be attractive or repulsive.
Electrical and gravitational forces follow similar equations with one main difference:
Work output divided by thermal energy input
The "efficiency" of a heat engine is defined to be
The number of protons in the nucleus of an atom of that element.
The 'atomic number" of an element that appears in the periodic table of the elements represents
Protons and neutrons.
The atomic nucleus contains only
Chemical energy
The basic energy resource that fueled the 'industrial revolution' was a form of
Grav E→ kin E + therm E
The energy transformation that occurs during downhill skiing is
Remains the same when the marble rolls from A to B
The figure above shows a marble rolling freely back and forth along a curved track. The track is positioned vertically. Assuming no friction and no air resistance, the total energy of the marble
Remains the same when the marble rolls from A to B
The figure above shows a marble rolling freely back and fourth along a curved track. The track is positioned vertically. Assuming no friction and no air resistance, the total energy of the marble
-10 mm
The figure shows two sets of water waves, created by two sources labeled "A" and "B". The solid half circles represent wave crest from A, and the dashed half circles represent wave crest from B. Suppose that individual wave crest from either source A or source B alone are 5 mm above the level of undisturbed water. Then the displacement of the water [above or below the level of the undisturbed water] at the point marked "x" [with the arrow point toward it] is
0 mm
The figure shows two sets of waves, created by two sources labeled "A" and "B." The solid half circles represent wave crests from A, and the dashed half-circles represent wave crests from B. Suppose that individual wave crests from either source A or source B alone are 3 mm above the level of the undisturbed water. Then the displacement of the water [above or below the level of the undisturbed water] at the point marked "x" [ with the arrow pointing toward it] is...
The internal combustion engine has all of these drawbacks
Which of the following is one of the drawbacks of the automobile engine?
a) Electricity from a nucleus power plant
Which of these if not used to replace gasoline as an automobile fuel, would not contribute to global warming?
The second law of thermodynamics
biggest reason why heat engines are far from 100% efficient is
No, because of the energy decrease of the radiation flowing through the leaf.
Does the growth of leaf violate the law of entropy, and why or why not?
A transfer of a disturbance from one point to another without any corresponding transfer of matter.
A "wave" could best be defined as
a transfer of disturbance from one point to another without any corresponding transfer of matter
A "wave" could best be defined as
300 J
A 100 W lightbulb has an energy efficiency of 5%. It is turned on for one minute. During this time, the visible radiant energy output of the lightbulb is
Both energy and energy quality remain unchanged but thermal energy is gained while kinetic energy is lost.
A block of wood slides to a stop along a tabletop. In this process
There is an electric field at X, but no magnetic field.
A charged particle is placed at rest in the middle of a vacuum chamber, an enclosure that has been emptied of matter. Consider some point X near a particular corner of the chamber. Neglecting all influences other than the charged particle, what can be said regarding electric field and magnetic fields at point X?
The sphere near the charged rod becomes positive and the other becomes negative.
A charged rod carrying a negative charge is brought near two spheres that are in contact with each other but insulated from the ground. If the two spheres are then separated, what kind of charge will be on the spheres?
A hot day
A day during which the atmospheric temperature was 40oC would be described as
Energy
A gas can containing a gallon of gasoline is stored in a basement. This gasoline contains...
Radiation from the sun separates chlorofluorocarbon resulting in free chlorine.
A key step in the destruction of ozone by chlorofluorocarbons is
Radiation from the sun separates chlorofluorocarbon, resulting in free chlorine.
A key step in the destruction of ozone by chlorofluorocarbons is
Operated for a long time
A low-power source of energy could put out a lot of work provided it...
Elastic energy
A motionless object could have
A positive ion
A neutral atom loses one of its electrons. It is then
18 gallons
A particular automobile operates at an efficiency of 10%. Suppose that 20 gallons are put into the auto's tank. Of this 20 gallons, how much will be "wasted", i.e. how much will be consumed to produce exhaust heat and in other ways that do not actually get the car down the road?
Thermal vibrations of molecules
A typical source of infrared radiation is
A two-dimensional wave
A water wave spreading out in a circle across the surface of a pond is an example of
Observing the light that passes through a narrow space between your fingers
A way to demonstrate to yourself that light is a wave is by
0 J
An object having a mass of 1000kg moves through outer space, far from all planets and stars and far from all gravitational influences, at a speed of 20 km/s (20,000 m/s). How much work is done on the meteor during a time interval of one second?
Yes, because the water itself doesn't go anyplace but simply oscilliates up and down.
Are small ripples sent out across the surface of a lake truly "waves" as that word is used in physics?
A person walks uphill
Chemical energy is transformed into gravitational energy when...
Greater because a hydro-electric plant is not a heat engine and so it does not have the large inefficiency implied by the second law of thermodynamics
Compared with the efficiency of a typical steam-electric generating plant, the efficiency of a typical hydroelectric generating plant is
The second law of thermodynamics
Conventional automobile efficiencies cannot conceivably be higher than about 25%, even with perfect engineering. This is due to...
Electromagnetic fields are physically real, though they are not made of atoms
Democritus believed that everything that is real is made of atoms. Are electromagnetic fields physically real, and are they made of atoms?
Yes, because electromagnetic fields contain energy, even thought they are not made atoms.
Do physicists consider electromagnetic fields to be real?
20 joules
Elizabeth lifts a 10 N book from the floor to the table, a height of 2 m. How much work does Elizabeth do?
The ability to do work
Energy could best be defined as....
Microscopic disorganization
Entropy is best defined as
A changing magnetic field creates an electric field.
Faraday's law tells us that
From measurements of chlorine monoxide and ozone in the Antarctic atmosphere as the sun reappeared in the spring.
How do we know that chlorine caused the ozone hole?
From computer calculations that "predict" 20th century temperatures based on natural variations, then on human-caused variations, and then on a mix of natural and human variations; the actual historical measurements then show that only natural variations are important.
How do we know whether or not global warming is caused by humans?
Electrons orbiting individual atoms in the magnet are all aligned together so their orbital -motion produces a large overall effect.
How does a permanent magnet work, i.e., what is the explanation of its magnetic effects?
both electric and magnetic
If two electrons are near each other and are moving past each other, the electromagnetic forces they exert on each other will be
Maxwell
The "Isaac Newton of electromagnetism" was
No, because it converts chemical energy directly to electric energy.
Is a fuel-cell vehicle properly described as a "heat engine"?
Yes, by measuring the CO2 content in deep ice cores.
Is it possible for scientists to determine the CO2 content of the atmosphere in pre-historic times?
O3 is a trace molecule in the atmosphere whereas O2 is not
It is easier to significantly alter Earth's O3 balance than its O2 balance because
electrons exist
J. J. Thompson's experiements with a type of invisible beam known as a cathode ray demonstrated that
Thermal energy is actually a form of energy
James Prescott Joule's experiments, such as stirring a container full of liquid, showed that
Thermal energy is actually a form of energy
James Prescott Joule's experiments, such as stirring a container full of liquid, showed that...
Traveling disturbances in an electromagnetic field
Light waves are
electromagnetic
Of the four known fundamental forces, the one that holds electrons into their orbit in atoms is
Four times as much
One car is traveling twice as fast as a second car. How much more work can the first car do compared to the second car, in smashing into a brick wall?
Nuclear power does not contribute to the global warming problem
One good argument in favor of nuclear power over coal power is that
Nonsense- no violations of this law have ever been observed
One situation in which the law of conservation of energy is violated is
Nonsense-no violations of this law have every been observed
One situation in which the law of conservation of energy is violated is
Gravitational
Physically, the type of energy represented by the water behind a dam is...
You would get more work, because heat engines are more efficient at converting thermal energy into work when the input temperature is higher
Suppose an automobile's fuel could be made to burn hotter without harming the engines operation. Would you still get the same amount of useful work from each gallon of gasoline?
They will exert electric forces but not magnetic forces
Suppose you charge two transparencies by rubbing and then hold them near each other but not touching. Regarding the electric and magnetic forces they exert on each other,
An electromagnetic wave whose frequency is 90 x 10(6) vibrations/seconds.
Talk-radio station KOOK is at approximately 90 megahertz on the radio dial. This means that KOOK broadcasts
the magnetic force exerted by electrons moving within the magnet, on electrons moving within the nails
The force that is exerted by a magnet as it picks up iron nails could be best described as
Thermal energy cannot be entirely converted into non-thermal forms of energy.
The second law of thermodynamics implies that
In order to preserve the law of conservation of energy in a certain type of nuclear process
The sub-atomic particle known as the "neutrino" was originally hypothesized
The law of conservation of energy
There are no known exceptions to
Infra-red, visible, and ultra-violet
Three main types of radiation produced by the sun are
b) A disturbance 1 cm deep
Two brief waves or "pulses" are sent down a rope, in opposite directions, as shown in the figure. Pulse A is 1 cm in height, and pulse B is 2 cm in depth. When they meet, they will create
Similarly-charged objects repel each other
Two transparency sheets are rubbed with tissue paper and then the two transparency sheets are held up near each other. This experiment demonstrates that
similarly charged objects repel each other
Two transparency sheets are rubbed with tissue paper and then two transparency sheets are held up near each other. This experiment demonstrates that
b) Y has the larger frequency and carries the greater energy
Two water waves, call them X and Y, have the same amplitude but different wavelengths: X has a larger wavelength than Y. Regarding their frequencies and their energies,
If the object does not move
Under what condition can a force act on an object and yet do no work on that object?
60 ohms
What should be the resistance of a light bulb in order for in to draw a 2 amp current when plugged into a 120-volt outlet?
The amount of electrical current flowing into one side of the battery is equal to the amount flowing out of its other side.
When a battery is used to light up a lightbulb
Reduced by a factor of 4
When the distance between the two charges is doubled, the force between them is
Thermal energy flows form your hand to the ice
When you touch a piece of ice,
The electromagnetic force acts at a distance with a delay time, rather than instantaneously
Which fundamental fact about te electromagnetic force explains why electromagnetic waves exist, rather than simple electromagnetic force?
The law of conservation of energy but not the second law of thermodynamics d) The second law of thermodynamics but not the law of conservation of energy
Which laws of physics, if any, distinguish between the backward and the forward direction in time?
A sports wave {called "the wave"} at a sports arena
Which of the following are true waves, as the word is defined in physics?
a sports wave [ called "the wave"] at a sports arena.
Which of the following are true waves, as the word is defined in physics?
Actually all od these travel at light speed.
Which of the following does not travel at light speed?
block of wood sliding to s sop along a table top
Which of the following is an "irreversible" process?
The energy stored in firewood that has been gathered for burning? The energy stored in your body, that enables you to do work
Which of the following is an example of chemical energy?
Hydro-electric generating plant
Which of the following is not a heat engine?
fossil fuels & fissionable material such as uranium & solar energy - all of the above are possible energy sources
Which of the following is not a possible energy source for a steam electric generating plant?
All of the above are possible energy sources.
Which of the following is not a possible energy source for a steam-electric generating plant?
a) Excess electrons slow onto both the brush and the hair, causing the hairs to repel each other and causing the brush to repel the hairs. b) The atoms of the brush and hair are heated, causing their electrons move faster, which spreads out the atoms and thus causes the hair to stand up. c) The atoms of the brush and hair are set into rapid vibration, causing them to emit electromagnetic waves, which causes the hairs to stand up. *d) Electrons are brushed either from the hair onto the brush, or vice-versa, causing the brush and hair to be charged, so that the hairs then repel each other while the brush attracts the hairs. e) Electrons are brushed either from the hair onto the brush, or vice-versa, causing the brush and hair to be charged so that they hairs then attract each other while the brush repels the hairs.
Which of these is the best explanation of the "electric hair" that can occur when some people brush their hair?
Gamma
Which part of the electromagnetic spectrum has the shortest wavelength?
Hydroelectric,, because it is not a heat engine and so is not restricted by the second law of thermodynamics.
Which type of generating plant would you expect to be more energy efficient, steam-electric or hydroelectric?
Because CO2 absorbs, or traps infra-red radiation
Why might excess C02 in the atmosphere heat up the earth?
Higher-energy electrons orbiting the nucleus in atoms
X-ray radiation typically comes from
16 J
You push your physics book across a table. The book weighs 8 N, you push with a steady 5 N force, and the force of friction against the book is 3 N. You push the distance of 2 m. The amount of work you do on the book is
98 X 10^6, Hz, at a speed of 300,000 km/s
Your radio is tuned to 98 on the FM dial. What electromagnetic wave frequency is your radio receiving, and how fast is this wave traveling?
it is a wheeled vehicle & it is not a heat engine
fundamental physical reason for the bicycle's high efficiency as a transportation device is
700 bulbs
typical automobile consumes about 70 kW of power from the gas tank. How many 100 watt light bulbs could this light up. If the energy were used to light electric to run the car?