Review questions
PffP Dec 9, 2010
One horsepower is equivalent to
what?
A. Heat from a sitting human
B. 1 BTU
C. 1 kilowatt
D. 1 joule per second
Which of these objects is the
smallest?
A. Electron
B. Proton
C. Quark
D. string
What type of radiation did George
Gamow realize should be detectable
from the earliest years of the
universe?
A. Infrared
B. Ultraviolet
C. Gamma rays
D. microwaves
D. Microwaves
Gamow realized that EM waves
emitted billions of light years away
by objects flying away from us very
quickly would be Doppler shifted
down into the microwave region.
If you double the absolute
temperature of an object, the
wavelength of emitted light _____
and the total radiation ______.
A.
B.
C.
D.
doubles; is reduced to half
increases by 16; doubles
is reduced by a factor of 4; doubles
is reduced to half; increases by 16
D. is reduced to half; increases by 16
All hot objects emit radiation. The
frequency (energy) of the radiation will
increase as the object heats up, so the
wavelength will decrease. L = 3000/T.
The total amount of radiation is
proportional to the fourth power of the
temperature.
To figure out when an animal had
died, you could measure…
A. Hydrogen-3 (tritium)
B. Carbon-14
C. Potassium-40
D. Uranium-235
B. Carbon-14
Living organisms breathe in C-14
from the atmosphere until they die.
Then it decays away at a predictable
rate.
According to the linear hypothesis,
how much radiation is required to
cause 1 cancer?
A. 1 rem
B. 1 Sievert
C. 25 rem
D. 25 Sieverts
D. 25 Sieverts
25 Sieverts=2500 rem
Approximately how many nuclear
weapons are currently in the U.S.
arsenal?
A. 3,000
B. 12,000
C. 25,000
D. 100,000
B. 12,000
Actually closer to about 12,500,
that’s many times more than would
be required to wipe out all human life
on Earth.
Which of the following is NOT true
of a breeder reactor?
A. It uses Uranium-238
B. It involves a nuclear chain reaction
C. It “breeds” mostly Plutonium-240
D. It can be used to generate electricity
C. It “breeds” mostly Plutonium240
In a breeder reactor, Pu-239 decays,
releasing 3 neutrons. 1 of those
causes another Pu-239 to decay, and
the other 2 are absorbed by U-238,
making more Pu-239.
A uranium-fueled nuclear reactor
requires what concentration of U235?
A.
B.
C.
D.
3%
10%
50%
80%
A. 3%
A bomb requires 80% U-235, but a reactor
requires much less because the chain reaction
proceeds more slowly and they use moderators to
slow the neutrons. Uranium in nature is less than
1% U-235.
An object’s kinetic energy depends
on…
A. Its volume and velocity
B. Its mass and velocity
C. Its volume and mass
D. Its volume, mass, and velocity
B. Its mass and velocity
KE=1/2mv2
A typical nuclear power plant
generates as much energy as exists
in…
A. 1 square meter of sunlight
B. 1 square mile of sunlight
C. 1 square kilometer of sunlight
D. 10 square kilometers of sunlight
C. 1 square kilometer of sunlight
A km2 of sunlight has about 1
gigawatt of power.
Which of the following has the
highest energy per gram?
A. A laptop battery
B. TNT
C. A meteor moving at 30km/sec
D. U-235
D. U-235
U-235 has about 200,000x the energy
per gram as a meteor.
About how many horsepower can a
typical human generate for an
extended period of time?
A.
B.
C.
D.
0.25
0.75
1.0
1.5
A. 0.25
World-class cyclists can generate
about 0.67 horsepower for over an
hour.
If the molecules in a gas all start to
move twice as quickly, what
happens to its temperature?
A. It stays the same
B. It doubles
C. It quadruples
D. There is not enough information
C. It quadruples
Temperature is average kinetic
energy, which is 1/2mv2
How much of the energy from
burning gasoline in your car actually
goes into moving the car?
A.
B.
C.
D.
10%
20%
50%
80%
B. 20%
The other 80% is lost as heat. An
electric motor can power a car with
about 85% efficiency. (1-6)
To use the energy in one pound of
fat per week (7 days), you have to
burn how many Calories per day?
A.
B.
C.
D.
100
150
300
500
D. 500
A pound of fat represents about 3500
Calories. You could also reduce your
food intake by 500 Calories per day
to get the same effect. (1-22)
My car can drive 300 miles with a 10gallon tank full of gasoline. About how
big would the tank have to be for the car
to travel the same distance using
pressurized hydrogen gas as fuel?
A. 3 gallons
B. 10 gallons
C. 30 gallons
D. 60 gallons
D. 60 gallons
Even if you liquefied the hydrogen, it
would still have 3x less energy per gallon
than gasoline. This also doesn’t include
the additional difficulty of using a highpressure tank. (Ch 1)
What was the energy equivalent
of the asteroid that killed the
dinosaurs?
A. 106 megatons of TNT
B. 10,000 times the nuclear arsenal
of Soviet-US during Cold War
C. 1010 nuclear bombs
D. 2.5 x 1012 tons of TNT
B. 10,000 times the entire SovietU.S. nuclear arsenal at the height
of the Cold War (1-25)
Which of the following is NOT a
type of heat flow?
A. conduction
B. diffusion
C. convection
D. radiation
B. diffusion
Diffusion refers to the movement of
particles from high to low
concentration. Convection,
conduction, and radiation are all ways
that heat moves. (2-24)
Molecules in air are typically
moving at about what speed?
A. 1 foot/sec
B. 10 feet/sec
C. 100 feet/sec
D. 1000 feet/sec
D. 1000 feet/sec
This is also approximately the speed of
sound, since in a gas the speed of sound is
limited by how quickly the molecules can
bump into each other. (2-4)
When I go to Britain and they tell
me that it’s 15 degrees Celsius
outside. What’s the temperature?
A.
B.
C.
D.
20 degrees Fahrenheit
80 degrees Fahrenheit
40 degrees Fahrenheit
60 degrees Fahrenheit
B. 60 degrees Fahrenheit
Tc = (TF – 32)(5/9) (2-7)
A mixture of helium atoms (weight
= 4 amu) and methane (weight = 16
amu) are at a constant temperature.
On average, how fast are the
methane molecules moving
compared to the helium?
A.
B.
C.
D.
2x slower
2x faster
4x slower
4x faster
A. 2x slower
Kinetic energy = ½mv2. If the
particles have the same KE, the
heavier particles must be moving
more slowly.
Earth lost its hydrogen due to which of
the following reasons:
A. Radiation
B. Entropy
C. Expansion
D. Gravity
D. Gravity
Jupiter and the Sun have much stronger
gravitational field than Earth, so they
kept theirs. (2-6)
The fraction of the U.S.
population that dies from cancer
is typically:
A. 1 in 100
B. 1 in 50
C. 1 in 5
D. Most Americans die from cancer
C. 1 in 5
Since 20% of people die from cancer
anyway, it is difficult to judge
whether a little bit of radiation is
causing additional cancers. (4-9)
.
Radioactivity in the Earth
leads to…
A. Energy for volcanoes
B. Helium for toy balloons
C. Heat for geysers
D. All of the above
D. All of the above
Radioactive decay generates warmth
and releases alpha particles (helium
nuclei). (4-23, 4-24)
Carbon-14 has…
A. 12 protons & 2 neutrons
B. 14 protons & 14 neutrons
C. 6 protons & 6 neutrons
D. 6 protons & 8 neutrons
D. 6 protons & 8 neutrons
All carbon atoms have 6 protons.
Most also have 6 neutrons, but C-14
has 2 extra neutrons. (4-18)
Which of the following would you
not expect to be radioactive
A. A bottle of tequila
B. Your smoke detector
C. The helium in a balloon
D. Your roommate
C. The helium in a balloon
Helium is a product of the radioactive
decay of uranium, but is not itself
radioactive. (4-23, 4-24)
According to the linear
hypothesis, exposure to 1 rem of
radiation would increase your
chance of developing cancer by
(about):
A.
B.
C.
D.
0.05%
0.1%
0.5%
1%
A. 0.05%
The linear hypothesis assumes that
2500 rem will cause 1 cancer, no
matter how it is distributed. 1/2500 =
0.04% (4-9)
A breeder reactor is designed to
produce
A.
B.
C.
D.
U-235
Tritium
U-238
Pu-239
D. Pu-239
In a breeder reactor, some of the extra
neutrons released the decay of Pu-239
are used to turn U-238 into…more Pu239 (5-24)
According to the text, the least
bad place to put nuclear waste
is…
A. In the sun
B. All the way into outer space
C. In our food
D. Underground
D. Underground
Putting it into space sounds like a
good idea…unless your rocket
explodes. (5-29, 5-30)
The dangerous radioactivity in
fallout comes from
A. Neutrons
B. Neutrinos
C. Gamma rays
D. Fission fragments
D. Fission fragments
Decaying radioactive material may
break up into smaller radioactive
particles with shorter half-lives. (528)
For an atomic bomb, the number
of doublings required is closest to
A.
B.
C.
D.
1023
235
80
16
C. 80
After 80 doublings,
1,200,000,000,000,000,000,000,000
atoms will have exploded. (5-4)