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. MicrowavesGamow 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. doubles; is reduced to half

B. increases by 16; doubles

C. is reduced by a factor of 4; doubles

D. 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-40D. 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 remB. 1 SievertC. 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. 12,000C. 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-238B. It involves a nuclear chain reactionC. It “breeds” mostly Plutonium-240

D. It can be used to generate electricity

C. It “breeds” mostly Plutonium-240

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 U-

235?A. 3%

B. 10%

C. 50%

D. 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 sunlightB. 1 square mile of sunlight

C. 1 square kilometer of sunlightD. 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. 0.25B. 0.75C. 1.0D. 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. 10%

B. 20%

C. 50%

D. 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. 100

B. 150

C. 300

D. 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 10-gallon 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 high-

pressure 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 Soviet-U.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/secB. 10 feet/sec

C. 100 feet/secD. 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. 20 degrees Fahrenheit

B. 80 degrees Fahrenheit

C. 40 degrees Fahrenheit

D. 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. 2x slower

B. 2x faster

C. 4x slower

D. 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 100B. 1 in 50C. 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 volcanoesB. Helium for toy balloons

C. Heat for geysersD. 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 neutronsB. 14 protons & 14 neutrons

C. 6 protons & 6 neutronsD. 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 tequilaB. Your smoke detector

C. The helium in a balloonD. 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. 0.05%B. 0.1%C. 0.5%D. 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. U-235B. TritiumC. U-238D. 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 Pu-

239 (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. NeutronsB. Neutrinos

C. Gamma raysD. Fission fragments

D. Fission fragments

Decaying radioactive material may break up into smaller radioactive

particles with shorter half-lives. (5-28)

For an atomic bomb, the number of doublings required is closest to

A. 1023

B. 235

C. 80

D. 16

C. 80

After 80 doublings, 1,200,000,000,000,000,000,000,000

atoms will have exploded. (5-4)