Control is exercised in a nuclear reactor by
absorbing excess neutrons with control rods
According to the principle of equivalence, observations made in a Newtonian gravitational field are indistinguishable from observations made in
an accelerating reference frame
Detonation of a fission type atomic bomb is started by
pressing together several small pieces of uranium
When a beta particle is ejected from a nucleus, the nucleus then has slightly ___ mass and ____ charge
smaller mass, significantly greater charge
Light bends when it
passes through a gravitational field and is observed from an accelerating reference frame
You and a friend share the same space when there is no
relative velocity between you
Most of the radioactivity from the natural sources that we personally encounter comes from
the Earth's crust
Alpha particles can be stopped by
A few sheets of paper, a sheet of aluminum, thick block of led
A gamma ray is emitted from a nucleus when
There is a transition between energy levels in the nucleus
When radium A=88 emits an alpha particle, the resulting nucleus has atomic number
86
The half life of carbon 14 is 5730 years. If a 1-gram sample of old carbon is 1/8 as radioactive as 1-gram of a current sample, then the age of the old sample is about
5730 x 3 = 17200
Fusing two helium nuclei yields a net
release of energy
As the speed of an object approaches c, the speed of light, the relativistic momentum of that object approaches
infinity
Energy released by the sun results from the process wherein atomic nuclei
combine
Consider a spaceship that moves toward you at .5c (half speed of light). It fires a probe toward you, relative to itself, at 0.5c. Relative to you, the probe approaches at about
.8c
Velocity at relativistic speeds
v=v1+v2/ (1+v1v2/c2)
Einstein's theory of gravitation obeys the correspondence principle because it
agrees with proven results of Newton's theory
Event A occurs before event B in a certain frame of reference. In another frame of reference, event A could occur
same time or after event b
Suppose your friend flies by you in a rocket ship traveling at 0.995c. How many seconds does your clock advance during the time you see his clock advance 1 second
10seconds
According to the special theory of relativity, ass laws of nature are the same in reference frames that
move at constant velocity
The atomic number of an element is the same as the number of its
protons
Which of the following is not a factor in determining whether a nucleus is stable (non-radioactive) or unstable (radioactive)?
Gravitational force
If you use the relativistic velocity-addition formula to add everyday velocities, you will get
a result almost identical to the classical result
The frequency of light emitted from helium atoms on the surface of the sun will be ____ the frequency of light emitted by helium on Earth.
lower than
A certain radioactive isotope placed near a Geiger counter registers 160 counts per second. Eight hours later, the counter registers 40 counts per second. What is the half life of the isotoope?
4 hrs
According to special relativity, one can travel at increased rates
only forward in time
Which of the following are characteristics of nuclear fusion power plants
A working fusion reactor has not been built yet, virtually no pollution, radioactive or otherwise, no risk of a reactor meltdown accident
At the top of a very tall skyscraper, a sensitive watch will appear to run
fast
According to the relativity theory, if a space trip finds a son or daughter biologically older than his or her parents, then the space trip is taken by the
parents
Compared to the mass of a uranium nucleus before splitting, the pieces it splits into have ___ mass
less mass
A woman standing on the ground sees a rocket ship move past her at 95% the speed of light. Compared to when the rocket is at rest, the woman measures the rocket's length as
shorter
The most harmful radiations are those that ___ living cells
damage living cells
The operation of a cloud chamber does not rely on
polarization
Clocks on a space ship moving very fast relative to the Earth run fast when viewed from
Niether place
The energy release in both fission and fusion is mainly in the form of
kinetic energy of fragments
In nuclear fission and nuclear fusion reactions, the amount of mass converted to energy of other forms is
less than 1%
In a one-g gravitational field, in one second, a light beam will curve beneath a perfectly straight line by
4.9m
A nuclear process that has relatively few radioactive by-products is
fusion
A beta particle is emitted from a nucleus when
a neutron is turned into a proton
The reduction of length due to motion is called length
contraction
An element will decay to an element with lower atomic number in the periodic table if it emits
an alpha particle
Our bodies are able to repair most kinds of molecular damage from radiation
if the radiation dose is not too intense
Consider a spaceship that moves toward you at 0.4c and fires a missile toward you, relative to itself at .5c. Relative to you, the missile approaches at about
.75c
If I run the 100m sprint with a speed of .98c, it appears to me that the length of the race is about
10m
According to the well known equation, energy equals mass times the speed of light squared,
mass and energy are related
The mass of an atomic nucleon is nearly _____ times the mass of an electron
2000
Compared to clocks in a stationary reference frame, clocks in a moving reference frame run
slower
The measured ratio of circumference to diameter on a disk is pi when the disk is
at rest
The half-life on an isotope is two days. At the end of eight days, how much of the isotope remains?
one-sixteenth
The function of graphite in the first atomic reactor was to
absorb fast neutrons
Which radiation has no electric charge associated with it?
gamma rays
Most of the radioactivity from man-made sources that we personally encounter comes from
medical x-rays
Compared to a watch at the Earth's pols, a watch at the Earth's equator should run
A tiny bit faster
Light bends when it
passive a massive star, gravitational field
Which is not a major challenge to space travel at relativistic speeds?
Time would speed up so much for the relativistic astronauts that they would likely age and die before they got very far
A spaceship that is traveling away from you at 0.4c, fires a photon beam back at you. You measure the photon beam's speed to be
c
Detonation of a fission type atomic bomb is started by
pressing together several pieces of uranium
Which of the following are beneficial applications of radioactivity
irradiation of the food supply
radioactive tracers in crop fertilizers
strong doses of radioactivity for cancer treatment