Physics 115 Final Review – 2016-7
Exam will be closed book; no calculators; no computers. NO ESSAY on the
final exam.
You can bring a 3 x 5 index card with whatever notes and equations
you want written on BOTH SIDES. Be sure to sign it and turn it in with your
exam.
Review session is on Sunday night January 22nd beginning at 7 pm. Check the
website and your email for the location (TBD).
We will run the REVIEW as last time –
PRINT OUT AND BRING THIS DOCUMENT AND ALL OTHER REVIEW
MATERIALS since the review will be individually paced based on questions
you pose.
In addition to answering these questions, check the Learning Goals to make
sure the questions cover the material adequately and there are no gaps in your
preparation.
REVIEW QUESTIONS:
Below are several questions that have been addressed during the course. This is not meant to be a
complete list, but simply examples of questions that address some of the learning goals. The
numbers in parentheses preceding each question correspond to the numbers of the learning goals
they address.
(2,6) What is energy? What is power? How do they differ? What are the units used to describe
each? What are the quantitative relations between Calories, joules, kilojoules? How many
bites of a chocolate bar contains a Calorie of energy? A kilojoule of energy?
(2,6) Know the relation between Calories, joules, kilojoules; and between kilowatts and
horsepower.
(1,6,7,8) How does the energy per gram of TNT compare to a cookie? Why do we use
TNT instead of cookies to blow up things? How do these compare to uranium, etc.?
Why isn’t uranium explosive? What forms of energy do each have?
(2,7) What is mass and what are its units? How many kg is 100 lbs? What is your mass in kg?
(1,4,7) What do bullets and asteroids have in common? Why are their energies so different? Is it
by a factor of 100, 1000, or what? Can you explain the number? How is this related to stopping
missiles? space travel?
(4,8) Why is hydrogen a potential fuel? How does it work? What are it advantages? Why is this
an example where it costs energy to make energy? Why aren’t we using hydrogen fuel already?
(3,6) What is kinetic energy? What is the formula? The units? How does it change if you double
the mass? The speed?
(3,14) Same questions for momentum.
(9,14) What is conservation of energy? Conservation of momentum? In what situations does
each apply? Name an example where you cannot use them to solve a problem even though it
involves predicting the motion of objects? Why can’t you use them in these cases?
(1,3,7,18) Why does a block of uranium have so much more energy than a fastball? (nuclear
energy is not good enough: microscopically, what kind of energy is being converted into heat?)
(4,12) Why do a plastic and glass cup at the same temperature feel as if they are at different
temperatures when you touch them?
(4,12) Explain why global warming causes the oceans to rise.
Explain why melting of icebergs does not affect the ocean level.
(1,3,9) How does an asteroid cause an explosion?
(2,10) What is heat? How is heat related to temperature? What is specific heat and what does it
depend on?
(3,9) What happens if you mix liquids with different temperatures? Given an example where you
can compute the final temperature after mixing two liquids at different temperatures. Give an
example where you cannot compute the final temperature even though you know the initial
temperatures and the volume of each of the two liquids.
(4,10) Is the specific heat of water greater or less than aluminum, and what does that information
tell us? For example, which is more difficult to heat? Which stores more heat energy?
(3,10) How is heat related to the physical properties of atoms: How does it depend on their mass
and speed?
(1,14) What is the typical speed of atoms and molecules in materials? Why?
(10,12) How is pressure related to temperature? How is this related to explosions?
(1,3,10) How does the kinetic energy of a fastball compare to its heat energy? Be quantitative.
(3,6,14) How can you use this compute the temperature the shuttle reaches when it enters and
slows down in the atmosphere?
(3,13) Why is converting kinetic energy to heat easy, but converting heat to kinetic energy hard?
What laws of thermodynamics are relevant? What is the maximum efficiency you can have?
What does it depend on?
(2,14,15) What is force? What are it units? How does it depend on mass and acceleration? What
does the law of action-reaction mean?
(3,14,15) What is the formula for gravitational potential energy? Where and how can you apply
this formula?
(14,15) Is an astronaut in orbit “weightless”? Explain. Is there a force of gravity on the
astronaut?
(15) Why does circular motion at constant speed require an external force? In what direction
must the net force be on an object in uniform circular motion?
(15) If an object travels at a constant velocity (zero acceleration), what can you conclude about
the NET force on the object? What can you conclude about the force of gravity on the object?
(1,17) How big is an atom? How big is a nucleus compared to an atom?
(15,16,19) What are alpha, beta, and gamma rays? Why are these rays more dangerous than the
heavier nuclei that produce them? Do they have equal penetrating power?
(17,18) What are atoms composed of? What are nuclei composed of? What is atomic number and
atomic mass? How does it depend on constituents of nuclei? Know how to balance nuclear
reaction equations.
(17,18) What is an isotope? In what ways are different isotopes of the same atom similar in
terms of their composition and physical properties? In what ways are they different?
(1,4) What is a rem? What is radiation poisoning? How is it different from getting cancer from
radiaton? What long term effects can low-level radiation have on humans? What is the linear
hypothesis and how do you use it? What is LD50?
(4,16) What is fission? What is a chain reaction? Explain in detail how neutrons
play a role and what condition needs to be satisfied to have a runaway chain
reaction.
(4,23) What is a wave? Compare transport of mass for a projectile vs. movement of energy in a
wave. How can waves be used to send information?
(4,23) What is the difference between a transverse versus longitudinal wave? Give examples of
each. Name a wave which is neither.
(3,21,22) What is the amplitude of a wave? its frequency? its wavelength? how are they related
to its speed? Is the relation the same for all kinds of waves?
(21,23) What properties of the medium does the speed depend on? (answer depends on the type
of wave)
(23) What is dispersion? Given an example. If a medium is dispersive, what does that say about
the speed of waves in it?
(4,23) Compare dispersion in deep water waves versus shallow water waves. How does speed of
shallow wave vary with depth? How is this related to tsunamis?
(23) What is refraction? How is related to changes in speed? What happens to frequency,
wavelength and speed of light as it travels from air to glass?
(24) What is diffraction? Give an example of diffraction of light? of sound?
(24) What happens to light from a hydrogen lamp when it passes through a diffraction grating?
(4,24) Why can you hear people across a lake at night, but not during the day?
(4,24) How is the physics of waves related to the “sound channel”?
(24) What is interference? What is the difference between constructive and destructive
interference?
(24) What is the interference pattern when a plane wave hits a wall with two slits? How does it
depend on the separation between slits?
(24) What is resonance? Given an example.
(3,26) What is the Coulomb force between two charges? How does it depend on the magnitude
of the charges? their distance?
(26,27) What happens to electric and magnetic fields if you move a charge? if you move a
magnet? how is this related to electromagnetic waves?
(1,4) What is the speed of light in vacuum? What is the typical speed of sound? How is this
related to lightning and thunder?
(28) What is the electromagnetic spectrum? Be able to order from highest to lowest frequency:
radio waves, microwaves, infrared, visible, ultraviolet, x-rays, gamma rays. Which type has the
highest energy per photon? Which has the lowest?
(29,30) What happens to the color of metal as you heat it in flame – that is, how does the color
depend on temperature? (Be able to make a sketch of intensity versus frequency.) Why was
this effect considered mysterious? How was the mystery solved?
(30) What is Planck’s law? What is a quantum? Which has greater energy, a quantum of x-rays
or a quantum of radio wave? Why?
(30) What is the photoelectric effect? How does the number of electrons ejected depend on
color? on intensity?
(30,4) Why does a hot gas of hydrogen only emit certain discrete colors (spectral lines)? How is
can this fact be used to determine the composition of stars far away?
(29,30) What was the problem with Rutherford’s idea that electrons orbit a nucleus in much the
same way as planets orbit the Sun? How did Bohr resolve this problem?
(3,30) Describe the Bohr model of the atom including his formula for energy levels.
(30) What is wave-particle duality? Give an example.
(30,31) What is the Heisenberg uncertainty principle and how is it related to the problem with
Rutherford’s model of the atom?
(29,30,31,3) What happens when you fire single photons (one at a time with a long interval
between firings) through a narrowly spaced pair of slits? what does this tell you about photons?
How does the pattern change if I close one slit? If I have both slits open but use a detector to
determine which slit the photon goes through? How is the pattern different if I use electrons
instead?
(29) Describe five observations that can only be explained by quantum physics. (Hint: there are
five referred to in the questions above.)
(33,5) Describe devices that can only function based on an understanding of quantum physics.
(32,5) What does quantum physics says about determinism?
(31) What is the role of “waves” in quantum theory?
(34,36,37) If I am moving towards you at 100,000 km/s and aim a laser at a target you are
holding, what speed do I observe the light traveling towards you? What speed do you observe?
Contrast how Newton would answer this question versus Einstein.
(3,35) What is the Lorentz factor, "gamma"? Compute it for v= (3/5)c.
(38) If gamma =10, and we each have identical clocks that tick once each second: at what rate
do you think my clock ticks? At what rate do I think your clock ticks? My clock measures 10
cm across, and you have the same kind of clock as me. What size do I think your clock is
compared to mine? What size do you think my clock is compared to yours? Who is right?
(38,39) How is this related to space travel? to the twin paradox?
(39) Explain the paradox of the polevaulter and the barn (from class).
(41) How is relativity relevant for particle accelerators? How can you test the twin paradox using
an unstable particle (like a muon)?