Final Exam

Work is the rate at which you expend energy.

FALSE

The energy an object has because of its position is called potential energy.

TRUE

The increase in potential energy caused by lifting an object can be calculated by multiplying its weight by its change in height

TRUE

Your electric bill for 1500 killowatt-hours is a charge for the power you have used that month.

FALSE

You do more work on yourself when you run up the stairs than when you walk slowly

FALSE

Plants convert radiant energy from the sun into chemical energy by a process called photosynthesis

TRUE

An object that falls twice as far will be moving twice as fast when it hits the ground

FALSE

As we deplete our coal reserves, we can replace this lost source of energy by increasing our output of hydroelectric power

FALSE

Energy is not conserved when a moving object slows to a stop

FALSE

Nearly all of the energy consumed today is provided by petroleum, coal, hydropower and nuclear sources

TRUE

A spring-loaded paper clamp exerts a force of 2 N on 10 sheets of paper it is holding tightly together. Is the clamp doing work as it holds the papers together?

FALSE

The watt (W) is a unit of

power

What are the units for the work that is done by a newton of force acting through a meter of distance

joule

Which one of the following has an appropriate unit? work-joule, force-newton, power-watt, or all of the above?

all of the above

Which one of the following does NOT have the same units as the others? kinetic energy, momentum, potential energy, work

momentum

A car is traveling twice as fast as an identical car. How much more work will be needed to stop the car travelling twice as fast?

four times as much

When a light bulb is rated at 60 W, it means that..

each second, the bulb converts 60 J of electrical energy to heat and light

Kinetic energy refers to

energy of motion

When you throw a ball into the air, its kinetic energy: equals 1/2mv^2, equals the work you did on the ball when you threw it, is converted to potential energy as it goes higher, aotb

all of the above

A flower pot falls off a window ledge 10 m above the ground. Its kinetic energy as it hits the ground is: the same as the potential energy it had before falling, equal to the work done in placing the pot on the ledge, equal to the loss of potential energy as a result of the fall, aotb

all of the above

The important variables in gravitational potential energy are the weight of an object and the

change of position

Two students stand poised to leap off a high dive structure into the swimming pool below. Student B is twice as massive as student A. Which is true?

student B did twice as much work climbing to the top of the structure

Roughly, what fraction of the USA’s current energy needs is supplied by coal?

20%

While exploring an ancient Mayan tomb, you discover that the walls are closing in on you. By exerting 400 N of force, you are able to keep the wall from coming closer. The work you are doing on the wall is..

zero, because the wall is not moving

The rate at which work is done is

power

A pendulum is pulled back to position a, then released. Where is its kinetic energy the maximum?

c – right before reaching the other side

Which of the following energy sources does not exist on or under Earth’s surface?

hydrogen

The smallest available geothermal resource is

steam

Which of the following is not a solar technology

geothermal hot water

An abundant but dirty energy source is

coal

Which of the following is a renewable energy source?

biodiesel

Which energy source produces no pollutants?

hydrogen

According to PE = mgh, gravitational potential energy is the same thing as

work against a vertical change of position

Two cars have the same mass, but one is moving three times as fast as the other is. How much more work will be needed to stop the faster care?

nine times as much

Kinetic energy can be measured in terms of

work done on an object to put it into motion or work done on a moving object to bring it to rest

Potential and kinetic energy are created when work is done to change a position (PE) or a state of motion (KE). Ignoring friction how does the amount of work done to make the change compare to the amount of PE or KE created?

both are the same

Which path would result in more work accomplished in moving a box to the same spot on a table?

all would be equal

The force exerted when doing work by lifting an object against gravity is measured in units of

N

The work accomplished by lifting an object against gravity is measured in units of

J

A unit of power is the

Nm/s

The attractive force between two unlike charges has the same strength as the repulsive force between two like charges

TRUE

The electrical force is much weaker than the force of gravity

FALSE

An object becomes positively charged by gaining protrons

FALSE

If you double the distance between two charged objects, you reduce the electrical force by a factor of four

TRUE

The volt is a measure of the work done by a battery as it forces a certain quantity of charges through a conductor

TRUE

The reading on your electric bill shows the amount of power you have used in a month

FALSE

The north end of a suspended magnet will point to the magnetic north pole

TRUE

Charge moving through a wire produces a magnetic field around the wire

TRUE

The resistance of an extension cord varies directly with the length of the cord

TRUE

Thomas Edison argued that our electrical system should use direct current because he felt that alternating current was dangerous

TRUE

A bird lands on a non-insulated, 80,000-volt high line. Will it receive a shock?

FALSE

Considering the separation of charges, is it possible to have a high voltage without any current?

TRUE

A neutral atom gains one or more electrons and is now called a

negative ion

The unit of electric charge is a

coulomb

Electric field lines are drawn

in such a way as to show the direction of the field

The ratio of work done to charge that is moved by a battery is a

volt

When a switch is closed in a DC electrical current (aotb)

electrons flow through the conductor at a very slow speed, the electric field moves through the conductor at nearly the speed of light, the current flow is proportional to the voltage

The electric field lines in the diagram below indicate that

1 is a (+) charge and 2 is a (-) charge (arrows going out of one and into two)

An electric current is measured in units of

amp

The size of a current in a conductor depends on the ______ as well as the voltage

resistance

The north end of a magnetic compass needle does not always point to the geographic North Pole because

the geographic and magnetic North Poles are not in the same place

The magnitude of the resistance of a wire depends on (aotb)

the length of the wire, the cross-sectional area of the wire, the temperature of the wire

If you multiply amp X ohm, the answers will be in units of

potential

Which of the following unit is actually a measure of a rate?

amp

If you were to mechanically rotate the armature in an electric motor

the motor wold behave like a generator

If you steadily pushed the bar magnet through a coil of wire as show,

a constant current would flow through the wire

If you stopped the magnet midway through the loop

the current would immediately drop to zero

Which of the following is a measure of electrical work?

kWh

Earth’s north magnetic pole

is actually a magnetic south pole

If you multiply amps x volts the answer will be in units of

power

The strength of a magnetic field around a current-carrying wire varies directly with the

amperage of the current

Reverse the direction of a current in a wire, and the magnetic filed around the wire will

have a reversed north pole direction

The operation of which of the following depends on the interaction between two magnetic fields? Car stereo speakers, telephone, relay circuit, aotb

all of the above

An electric meter meausres

the strength of a magnetic field

When a loop of wire cuts across magnetic field lines or when magnetic field lines move across a loop of wire

electrons are pushed toward on end of the loop

In order to be operational, a complete electric circuit must contain a source of energy, a device that does work, and

a conductor from the source to the working device and another conductor back to the source

Which variable is inversely proportional to the resistance

cross-sectional area of conductor

A ratio of joules per coulomb (J/C) is also known of as a

volt

What is the voltage in the secondary coil if the primary coil is supplied with 120 V

240 V

What is the current in the secondary if the current is the primary coil is 5.0 A

2.5 A

A fluorescent light source emits light as a result of high temperature

FALSE

The radiation from the Sun is most intense near the yellow-green wavelength

TRUE

The change in the direction of light as it passes through the boundary between two media is called refraction

TRUE

The angle of incidence is equal to the angle of refraction

FALSE

The slower light travels in a given medium, the greater the index of refraction

TRUE

Longer wavelengths are affected more by a prism or water droplets than are the shorter wavelengths

FALSE

The sky appears blue due to the light reflected from the oceans

FALSE

Glare is light that tends to be polarized predominantly in the horizontal plane

TRUE

Ultraviolet light carries more energy than infrared radiation

TRUE

Interference is a property of light most easily explained by the particle model

FALSE

Which of the following does not emit light? candle flame, sun, moon, burning coal

the moon

When an electric stove element is hot enough, it gives off a dull red glow. When it cools to the point that it no longer glows it will

emit longer wavelength radiation

You are able to see non-luminous objects because light has undergone

diffuse reflection

The frequency of radiation is

none of these

Interference can be most easily explained in terms of the

wave model of light

Today, light is understood to be adequately explained

as having both wave and particle behavior

Max Planck discovered that the blackbody radiation emitted by vibrating molecules

appeared to come in multiples of certain fixed amounts

The photoelectric effect could not be adequately explained with wave model of light because

the energy of the ejected electrons did not depend upon the intensity

The Sun appears reddish as it sets because

more of the shorter, bluer wavelengths have been scattered away

The image formed by a plane mirror is

virtual

The index of refraction for flint glass is 1.5. This means that

The speed of light is slower in this medium than it is in vacuum

Total internal reflection: occurs when light strikes an interface at greater than the critical angle, accounts for the brilliance of cut diamonds, allows light to travel in a curved path inside an optic fiber, aotb

aotb

When monochromatic light from two slits arrive at a point on a screen out of phase

a dark region is produced

A prism separates the colors of sunlight into a spectrum because

each wavelength of light has its own index of refrection

Polarized light vibrates

only in one plane

A luminous object is an object that

produces light

An image that does not have light rays coming from the image, but is the result of your brain’s interpretations of light rays is called a

virtual image

The sky appears to be blue because

blue light has short wavelengths and is scattered most

When you see a rainbow, you know for sure that

you are between the Sun in one direction and falling rain in the other direction

If you want to see your whole image in a mirror, from head to foot, you will need a flat mirror that is

at least half as tall as you are

Green grass absorbs

all light but green light

Farsightedness, or hyperopia, can be corrected with what type of lens?

convex

A pencil is placed in a glass of water. The pencil appears to be bent. This is an example of

refraction

A one-way mirror works because it

reflects and transmits light at the same time

A mirage is caused by hot air near the ground

refracting light rays upward

A rainbow always appears

in the part of the sky opposite from the Sun

Polarizing sunglasses are useful because they are able to

absorb reflected light, which is polarized

Nearsightedness, or myopia, can be corrected with what type of lens?

concave

What are the units of h in the equation E = hf?

J . S

The colors of the visible spectrum can be measured in units of: wavelength, frequency, energy, aotb

aotb