Physics exam 2
less.
A 100-Watt lamp glows brighter than a 25-Watt lamp. The electrical resistance of the 100-Watt lamp must be
1 m
A 340-hertz sound wave travels at 340 m/s in air with a wavelength of
2.4 ohms
A 4-ohm resistor is connected in parallel with a 6-ohm resistor. This combination produces an equivalent resistance of
Both have the same current
A 60-W light bulb and a 100-W light bulb are connected in series to a 120 V outlet. Which light bulb has more current in it?
either positively or negatively.
A balloon will stick to a wooden wall if the balloon is charged
both charge and energy.
A capacitor is used to store
R = 17 Ω
A certain device in a 170-V circuit has a current rating of 10A . What is the resistance of the device (how many ohms)? I(A) = V(V) / R(Ω)
fuse.
A circuit breaker often serves the same purpose as a
through both the battery and the rest of the circuit.
A circuit is powered with a battery. Charge flows
none of these
A conductor differs from an insulator in that a conductor
repulsive interaction.
A difference between electric forces and gravitational forces is that gravitational forces are not affected by
E = 1.7×10^6 V/m
A droplet of ink in an industrial ink-jet printer carries a charge of 1.7×10−10C and is deflected onto paper by a force of 2.9×10−4N. Find the strength of the electric field to produce this force. E=F(N)/q(C)
$ 2.20
A heater uses 20 A when used in a 110-V line. If electric power costs 10 cents per kilowatt hour, the cost of running the heater for 10 hours is
positively charged.
A negatively charged rod is held near a metal can that rests on a dry wood table. If you touch the opposite side of the can momentarily with your finger, the can is then
12,800 W
A power line with a resistance of 2 ohms has a current of 80 A in it. The power dissipated in the line is
increases
A railroad locomotive is at rest with its whistle shrieking, then starts moving toward you. Does the frequency of sound that you hear increase, decrease, or stay the same?
a wave reflects upon itself.
A standing wave occurs when
rotation
A torque acting on an object tends to produce
100 hertz
A tuning fork of frequency 200 hertz will resonate if a sound wave incident on it has a frequency of
generator
Alternating current is normally produced by a
is moving away from Earth
An astronomer notices that radiation emitted by a star is slightly redshifted (the wavelength is longer). This means that the star _________.
5
An electric heater is rated at 300 W when used in a 110-V circuit. The safety fuse in the circuit can handle 15 A of current. How many heaters can be safely operated in the circuit?
attract each other.
An electron and a proton
GeV
An electron volt, eV, is a unit of energy. Which is larger, a GeV or a MeV?
V = 1.4×10^5 V
An energy of 0.15J is stored in the metal sphere on top of a Van de Graaff generator. A spark carrying 1.1 micro-coulomb (1.1×10−6C ) discharges the sphere. Find the sphere's potential relative to ground. V(V)= W(J) / q(C)
nearest the rim.
An industrial flywheel has a greater rotational inertia when most of its mass is
0.5 hertz
An object that completes 10 vibrations in 20 seconds has a frequency of
h= 4590m
An oceanic depth-sounding vessel surveys the ocean bottom with ultrasonic waves that travel 1530 m/s in sea-water. The time delay of the echo to the ocean floor and back is 6.00s .Find the depth of the water directly below the vessel
decreases.
As more lamps are put into a series circuit, the overall current in the power source
Felec/Fgrav = 2⋅10^39
Atomic physicists ignore the effect of gravity within an atom. To see why, calculate and compare the gravitational and electrical forces between an electron and a proton separated by 10^−10 m. The charges and masses are given in the textbook.
I= 0.53 A
Calculate the current in the 300-Ω filament of a bulb connected to a 160-V line. I(A) = V(V) / R(Ω)
I= 7.7 x 10^-3 A
Calculate the current that moves through your fingers (resistance 700Ω ) when you touch them to the terminals of a 5.4-V battery. I(A) = V(V) / R(Ω)
F= 320N
Calculate the force of friction that keeps a 90-kg person sitting on the edge of a horizontal rotating platform when the person sits 2.2m from the center of the platform and has a tangential speed of 2.8m/s . Centripetal Force: F=mv^2/r
P= 81 W
Calculate the power of a device that carries 0.54A when impressed with 150V. Power(W) = I(A) x V(V)
F=6.3N
Calculate the tension in a horizontal string that whirls a 1.7-kg toy in a circle of radius 2.1m when it moves at 2.8m/s on an icy surface. Centripetal Force: F=mv^2/r
τ =8.7 Nm
Calculate the torque produced by a 58-N perpendicular force at the end of a 0.15-m-long wrench. Torque = Lever Arm × Force
no
Can a force produce a torque when there is no lever arm?
resonance
Caruso is said to have made a crystal chandelier shatter with his voice. This is a demonstration of
loosely bound.
Charge carriers in a metal are electrons rather than protons because electrons are
less current
Compared to a single lamp connected to a battery, two identical lamps connected in series to the same battery will carry
twice as fast
Consider a string with several rocks tied along its length at equally spaced intervals. You whirl the string overhead so that the rocks follow circular paths. Compared to a rock in the middle of the string, a rock at the outer end moves
Sue's wheels have the greater rotational speed.
Dan and Sue cycle at the same speed. The tires on Dan's bike are larger in diameter than those on Sue's bike. Which wheels, if either, have the greater rotational speed?
none of these
Double the frequency of sound and you also double its
I= 6.9 A
Given that the power consumed by a device is 900W operating on a 130-V line, calculate the amount of current it draws. Power(W) = I(A) x V(V)
increases
Heat a copper wire and its electric resistance
I= 0.47 A
How many amperes flow through a 56-W bulb connected in a 120-V circuit? Power(W) = I(A) x V(V)
increase
If the Earth rotated more slowly about its axis, your apparent weight would
positively charged
If the atoms of one object (initially neutral) have electrons rubbed off through friction with a second object, the first object becomes ________.
decreases by a factor of 4
If the distance between two charged objects is doubled, the resulting electric force on each object __________.
L= 630 (kg x m^2)/s
If the force of friction that keeps a 50-kg person sitting on the edge of a horizontal rotating platform when the person sits 1.9m from the center of the platform and has a tangential speed of 6.6m/s , what will be the person's angular momentum? Angular Momentum = mvr
shorter
If the world's populations moved to the North Pole and the South Pole, would the 24-hour day become longer, shorter, or stay the same?
d= 5100 km
Imagine a Rip van Winkle type who lives in the mountains. Just before going to sleep, he yells, "WAKE UP", and the sound echoes off the nearest mountain and returns 8.4 hours later. Find the distance between Rip and the imaginary mountain.
110 joules of energy are given up by each coulomb of charge making up the current in the circuit.
In a 110-volt circuit containing a lamp in series with the voltage source
a fraction of a centimeter per second.
In a common dc circuit, electrons move at speeds of
electrons that surround the nucleus.
In an electrically neutral atom the number of protons in the nucleus is equal to the number of
wood.
In the unlikely case of a lightning strike, it is worse to be inside a building framed with
...
Object A is attracted to object B and repelled by object C. All three objects are charged. What would happen if object B and object C were brought together?
They would be attracted to each other.
Object A is attracted to object B and repelled by object C. All three objects are charged. What would happen if object B and object C were brought together?
the same.
Particle A has twice the charge of nearby particle B. Compared to the force on Particle A, the force on Particle B is
steel
Sound travels faster in
increases
Stretch a copper wire so that it is thinner and the resistance between its ends
positive ion
Strip electrons from an atom and the atom becomes a
1059 hertz
Suppose you sound a 1056-hertz tuning fork at the same time you strike a note on the piano and hear 2 beats/second. You tighten the piano string very slightly and now hear 3 beats/second. What is the frequency of the piano string?
electrons
The basic reason why things become electrically charged is that the atoms (or molecules) of some materials hold on to their _______ better than those of other materials.
a proton.
The direction of an electric field is the direction of the force that the field would exert on
none of the above choices are correct
The electric field around an isolated electron has a certain strength 1 cm from the electron. The electric field strength 2 cm from the electron is
close together.
The electrical force between charges is strongest when the charges are
speed
The explanation for refraction must involve a change in
low
The frequencies of sound that carry farther in air are
parallel with a switch for each.
The headlights, radio, and defroster fan in an automobile are connected in
E = 1.8×10^8 J
The potential difference between a storm cloud and the ground is 100 million V. If a charge of 1.8C flashes in a bolt from cloud to Earth, what is the change of potential energy of the charge? V(V)= W(J) / q(C)
discharge the structure to which it is attached.
The primary purpose of a lightning rod is to
straight
The rotational inertia of your leg is greater when your leg is
atoms in the light bulb filament.
The source of electrons lighting an incandescent ac light bulb is
vibrating
The source of every sound is something that is
the air temperature
The speed of a sound wave in air depends on
a specific large number of electrons.
The unit of electric charge, the coulomb, is the charge on
long
The wavelengths of sound that carry farther in air are relatively
the same electrons.
There are electrons in the filament of the ac lamp in your bedroom. When you turn on the lamp and it glows, the glowing comes from
11 times as great
Three resistors, 1-ohm, 2-ohm, and 3- ohm are connected in parallel. If they were connected in series instead their equivalent resistance would be
its charges have been rearranged.
To say that an object is electrically polarized is to say
F
Two charged particles attract each other with a force F. If the charges of both particles are doubled, and the distance between them also doubled, then the force of attraction will be
F/2
Two charged particles repel each other with a force F. If the charge of one of the particles is doubled and the distance between them is also doubled, then the force will be
0.11 N
Two charges separated by one meter exert 1-N forces on each other. If the charges are pulled to 3-m separation distance, the force on each charge will be
16 N.
Two charges separated by one meter exert 1-N forces on each other. If the charges are pushed to 1/4 meter separation, the force on each charge will be
1/9 E0
Two conducting spheres are each given a charge Q. The radius of the larger sphere is three times greater than that of the smaller sphere. If the electric field just outside of the smaller sphere is E0, then the electric field just outside of the larger sphere is
larger in the lamp with the thick filament.
Two lamps, one with a thick filament and one with a thin filament of the same material, are connected in parallel to a battery. The current is
greater across the lamp with the thin filament.
Two lamps, one with a thick filament and one with a thin filament of the same material, are connected in series to a battery. The voltage is
the same in both lamps.
Two lamps, one with a thick filament and one with a thin filament, are connected in parallel to a battery. The voltage is
the same in each lamp.
Two lamps, one with a thick filament and one with a thin filament, are connected in series. The current is
F= 27 N
Two pellets, each with a charge of 1.2 microcoulomb (1.2×10−6C ), are located 2.2cm (2.2×10−2m ) apart. Find the electric force between them.
Q = 3.5×10^−6 C
Two point charges are separated by 7.0cm . The attractive force between them is 22N . Suppose that the charges attracting each other have equal magnitude. Rearrange Coulomb's law and find the magnitude of each charge.
the electrical repulsion.
Two protons attract each other gravitationally and repel each other electrically. By far the greater force is
I= 8.0 A
Using the formula power = current × voltage, find the current drawn by a 1200-W toaster connected to 150V .
f1,f2,f3 = 2,3,5 Hz
What beat frequencies are possible with tuning forks of frequencies 256, 259, and 261Hz ?
electrons were removed.
What causes an atom to become positively charged?
Some electrons in conductors are weakly attached to the atoms, and all electrons in insulators are strongly attached to the atoms.
What is the main difference between a conductor, such as copper, and an insulator, such as plastic?
Current = Voltage Difference / Resistance
What is the relationship between current, resistance, and voltage difference?
none of these.
What is the resistance of a 120-W incandescent lamp connected to a 120-V power supply?
joule
What unit is represented by (watt x second)?
ampere
What unit is represented by coulomb per second?
volt
What unit is represented by joule per coulomb?
5 ohms
When a 10-V battery is connected to a resistor, the current in the resistor is 2 A. What is the resistor's value?
less than 1 cm/s
When a light switch is turned on in a dc circuit, the average speed of electrons in the lamp is
more than the resistance of either lamp.
When two lamps are connected in series to a battery, the electrical resistance that the battery senses is
electrical
Which force binds atoms together to form molecules?
1 kg
A 1-kg rock is suspended from the tip of a meter stick at the 0-cm mark so that the meter stick balances like a seesaw when the fulcrum is at the 25-cm mark. From this information, what is the mass of the meter stick?
2 seconds
A 5-kg mass is attached to a spring and is oscillating with a period of 2 seconds and an amplitude of 5 cm. If the amplitude is made to be 10 cm, the period of oscillation will be _____.
L= 390 (kg x m^2)/s
Calculate the angular momentum of the person if the force of friction that keeps a 65-kg person sitting on the edge of a horizontal rotating platform when the person sits 2.5m from the center of the platform and has a tangential speed of 2.4m/s . Angular Momentum = mvr
no. yes
Does the period of a pendulum depend on the mass of the bob? On the length of the string?
door A
Door B is twice as wide as door A, but both doors have the same height and the same mass. A person pushes on the edge of the two doors with the same force. Which door opens more quickly?
amplitude
For AM radio, the A stands for
the resultant forces and torques must both be zero.
For a system in mechanical equilibrium
near the outside.
Horses that move with the fastest linear speed on a merry-go-round are located
The rotational inertia of the rod with the mass closer to the top is greater than the rotational inertia of the rod with the mass closer to the bottom.
How does the rotational inertia of the rod with the mass toward the bottom compare with the rotational inertia of the mass toward the top?
The torque due to the weight of the shorter side (the bristles of the broom) is equal in magnitude to the torque due to the weight of the longer side, and opposite in direction.
How does the torque due to the weight of one side of the broom exerted around the balance point compare with the torque exerted by the weight of the other side of the broom around the balance point?
3
How many nodes, not including the endpoints, are there in a standing wave that is two wavelengths long?
increase. decrease
If a pendulum is shortened, does its frequency increase or decrease? What about its period?
double
If a turntable's rotational speed is doubled, then the linear speed of a pet hamster sitting on the edge of the record will
faster in helium than in air.
Inhaling helium increases the pitch of your voice. One reason for this is that sound travels
It is easier for the performer to balance a long rod held vertically with people at the other end because the rotational inertia is greater.
Is it easier for a circus performer to balance a long rod held vertically with people hanging off the other end, or the same long rod without the people at the other end, and why?
Joe and Sally have the same angular velocity.
Joe lives on the equator, and Sally lives in Alaska. Which person has the higher angular velocity due to Earth's rotation?
Joe
Joe lives on the equator, and Sally lives in Alaska. Which person has the higher speed due to Earth's rotation?
amplitude, frequency, wavelength, and speed.
Like a transverse wave, a longitudinal wave has
1/3 the distance from the fulcrum.
On a balanced seesaw, a boy three times as heavy as his partner sits
two
Put a pipe over the end of a wrench when trying to turn a stubborn nut on a bolt, to effectively make the wrench handle twice as long, you'll multiply the torque by
3.0 m.
Radio waves travel at the speed of light, 300,000 km/s. The wavelength of a radio wave received at 100 megahertz is
blue light
Red light has a longer wavelength than blue light. Which type of light has a higher frequency? (The speed of light is independent of wavelength.)
least amount of energy input
Resonance can be looked at as forced vibration with the
four times faster than
Suppose Sally lived on the equator of a planet that had a radius twice that of Earth's radius and that rotated with twice the angular velocity (so one day would be 12 hours long). Sally's speed on this planet would be _______ Joe's speed (who lives on Earth's equator).
2 m/s
Suppose the circumference of a bicycle wheel is 2 meters. If it rotates at 1 revolution per second when you are riding the bicycle, then your speed will be
remains the same, but the RPMs decrease.
Suppose you are at the center of a large freely-rotating horizontal turntable in a carnival funhouse. As you crawl toward the edge, the angular momentum of you and the turntable
20 hertz to 20,000 hertz.
The approximate range of human hearing is
6 hertz
The beat frequency produced when a 240 hertz tuning fork and a 246 hertz tuning fork are sounded together is
increased internal energy of the air.
The energy of sound in air eventually becomes
above a place of support.
The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is
1/60 hertz.
The frequency of the second hand on a clock is
small bell
The object with the highest natural frequency is a
shortest period
The pendulum with the greatest frequency is the pendulum with the
60 seconds
The period of the second hand on a clock is
Both A and B are correct
The tapered shape of the parts of the wheels that ride on railroad tracks allows opposite wheels to
at right angles to the direction of wave travel.
The vibrations of a transverse wave move in a direction
the 5-kg block
Two blocks, one with a mass of 10 kg and another with a mass of 5 kg, are hanging on identical springs. If both blocks are displaced and released, which one will oscillate with a higher frequency?
wave 1
Two waves with the same wavelength are moving to the right. Wave 1 is moving faster than wave 2. Which wave has a higher frequency?
f = 10 Hz
What is the frequency, in hertz, that corresponds to each of the following periods? 0.10 s
f= 60 Hz
What is the frequency, in hertz, that corresponds to each of the following periods? 1/60 s
f= 0.20 Hz
What is the frequency, in hertz, that corresponds to each of the following periods? 5.0 s
Rotational inertia depends on whether the mass is farther or closer to the point of rotation. The farther the mass is, the higher the rotational inertia.
Why does the rotational inertia of the rod with the attached mass closer to your hand compare the way it does with the rotational inertial of the rod with the attached mass farther away?
toward you
A Doppler effect occurs when a source of sound moves
an unbalanced torque
A ball rolls down a hill mainly because of
higher
A bat chirps as it flies toward a wall. Is the frequency of the echoed chirps it receives higher, lower, or the same as the emitted ones?
d= 20 m
A bat flying in a cave emits a sound and receives its echo 0.12s later. Find its distance from the cave wall.
highest, farthest from your hand
A broom is easier to balance on its end when the heavier end (the brush end) is
coin
A coin and a ring roll down an incline starting at the same time. The one to reach the bottom first will be the
3
A general rule for estimating the distance in kilometers between an observer and a lightning bolt is to count the number of seconds between seeing the lightning and hearing it, and dividing by
1.0 meter
A girl weighs 60 pounds and is sitting on the teeter-totter 3 m from the center. How far from the center should a 180-pound boy sit so that the teeter-totter balances?
λ = 25 m
A grunting porpoise emits sound at 61Hz . What is the wavelength of this sound in water, where the speed of sound is 1500 m/s?
0
A piano tuner knows that a key on the piano is tuned to the frequency of his tuning fork when he strikes them at the same time and the number of beats he hears each second is
3 m
A wave oscillates up and down two complete cycles each second. If the wave travels an average distance of 6 meters in one second, its wavelength is
not enough information to say
A wave travels an average distance of 1 meter in 1 second with a frequency of 1 hertz. Its amplitude is
vibration
A wiggle in time is a
It is easier when the mass is farther from your hand.
Is it easier to balance a long rod with a mass attached to it when the mass is closer to your hand or when the mass is farther away?
smaller than that of the wide part.
Since each rolling wheel of a railroad train is tapered, the narrow part of the wheel has a tangential speed that is
amplitude
Some of a wave's energy dissipates as heat. In time, this will reduce the wave's
true
Sound waves can interfere with one another so that no sound results.
at the center of the disk
The center of gravity of a circular disk of sheet metal is
out of step
To say that one wave is out of phase with another is to say that the waves are
wide handle
To turn a stubborn screw, it is best to use a screwdriver that has a
5.0 s
What is the period, in seconds, that corresponds to each of the following frequencies? 0.2 Hz
0.1 s
What is the period, in seconds, that corresponds to each of the following frequencies? 10 Hz
1.7 x 10^-2 s
What is the period, in seconds, that corresponds to each of the following frequencies? 60 Hz
λ = 1.1 m
What is the wavelength of a 310-Hz tone in air?
λ = 1.1×10−2 m
What is the wavelength of a 31000-Hz ultrasonic wave in air?
The shorter side, where the bristles of the broom are, has a greater weight than the handle.
When Dr. Hewitt cuts the broom right through the center of gravity, how do the weights of the two sides of the broom compare?
becomes shorter
When the handle of a tuning fork is held solidly against a table, the sound becomes louder and the time that the fork keeps vibrating
upwards
When the speed of sound near the ground is greater than it is at higher altitudes, the sound tends to be bent
at the balance point
Where is the center of gravity of the broom that Dr. Hewitt holds up?
radio waves
Which doesn't belong to the same family?
a long pendulum
Which has the longer period, a short or a long pendulum?
outside horse
Which moves faster in m/s on a merry-go-round: a horse on the inside or a horse on the outside near the outer rail?
sound
Which of the following is not a transverse wave?
0.33 cycles per second
You are floating in the ocean, and waves with a wavelength of 12 meters are causing you to bob up and down. If the waves are moving with a speed of 4 m/s, what is your frequency of oscillation?
d= 340 m
You watch distant Sally Homemaker driving nails into a front porch at a regular rate of 1 stroke per second. You hear the sound of the blows exactly synchronized with the blows you see. And then you hear one more blow after you see the hammering stop.Calculate the distance of Sally from you.
doubles.
Your pet hamster sits on a record player whose angular speed is constant. If he moves to a point twice as far from the center, then his linear speed
