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PHY 115
Learning Goals Outline
October 2011
Unit 1: Energy and Power
1. Define and list the units for:
a) heat
b) energy
c) mass
d) power
 How is energy related to heat?
 What is energy? What is power? How do they differ? What are the units
used to describe both?
 What is mass and what are its units? How may kg is 100 lbs?
2. Include units with physical quantities, and ask for units if none are given
3. Convert between basic units
 What are the relations between Calories, joules, kilojoules?
4. Relate physical quantities to common experience
5. Estimate physical quantities (what numbers are or aren't reasonable answers to a
problem)
6. Distinguish ideas grounded in scientific models from those that are not
7. Identify explosions as examples of energy transformations
 What is an explosion? Why is the difference between an explosion on
Earth and an explosion in space?
8. Compare substances quantitatively using the measure of energy per unit mass
 Energy game: How does the energy per gram of TNT compare to a
cookie, compare to uranium, etc.? What forms of energy do each
have?
9. Observe that an object's appearance does not reveal how much energy it contains.
 Energy game. What forms of energy does each energy source have?
10. Relate quantitative differences in energy concentration to political and economic
events
11. Apply proportional reasoning to the dependence of kinetic energy on the square of
velocity
 What do bullets and asteroids have in common? Why are their
energies so different?
12. Quantitatively and qualitatively compare the kinetic energies of common objects
13. Analyze equations to determine when physical quantities are more sensitive to
changes in one variable compared to another
 Is kinetic energy more sensitive to changes in speed or changes in
mass?
14. State the principle of conservation of energy
15. Distinguish something that is energetic from something that is powerful
16. Identify when you would want something that is energetic, versus something
powerful, versus both
 What do TNT and cookies have in common? What is different? How
does this affect their use?
17. Distinguish between power used and useful power

Is it possible for a 25 W lightbulb to be as bright as a 100 W lightbulb?
If not, why not? If so, how?
18. Recognize the cost of making and transporting energy sources
19. Evaluate trade-offs between different sources of energy
 Why is hydrogen a potential fuel? How does it work? Why is this an
example where it costs energy to make energy? Why aren’t we using
hydrogen instead of gasoline already?
 When the Sun is shining, how much solar energy falls on a square
meter of the Earth each second? Why do we express this in terms of
power? Is this energy usable? Practical?
Unit 2: Atoms & Heat
20. Define and list the units (and convert among common units) for:
a) Temperature
b) Specific heat
 How is heat related to temperature?
 What is specific heat and what does it depend on?
21. Know the 0th Law of Thermodynamics (equilibrium)
22. Explain the difference between heat and temperature
23. Relate heat energy to the kinetic energy of atoms and molecules
 How is temperature related to the physical properties of atoms: How
does it depend on their mass and speed?
24. Apply proportional reasoning and the equation for specific heat to quantitatively
relate heat energy and temperature
25. Compare the specific heats of different materials and interpret the meaning of the
differences
 Is the specific heat of water greater or less than aluminum, and what
does that information tell us?
26. Relate quantitative differences in specific heats to common experiences and realworld applications
27. Apply heat conduction to explain why different materials at the same temperature feel
like they have different temperatures
 Why do a plastic and glass cup at the same temperature feel as if they
are at different temperatures when you touch them?
28. Know the 1st Law of Thermodynamics (energy is conserved)
29. Apply the 1st Law of Thermodynamics to predict the final temperature of a mixture of
liquids, given the initial amounts and temperatures of the liquids
 If you mix two cups of water at different temperatures, what
temperature will they reach over time? How does it depend on the
temperature and volume of water in the two cups?
30. Know the approximate speed of sound, and that this equals the typical velocity of
molecules
 What is the typical speed of atoms and molecules in materials?
31. Relate the quantitative difference between the speed of light and the speed of sound to
common experience
 How is the typical speed of atoms and molecules related to lightning?
32. Estimate the heat energy in ordinary objects; quantitatively compare an object's
kinetic energy to its heat energy
 How does the kinetic energy of a fastball (when thrown by a pitcher)
compare to its heat energy after it is caught? Be quantitative.
33. Estimate the final temperature of an object moving through the atmosphere if all of its
kinetic energy is converted into heat energy (through friction)
 How does an asteroid cause an explosion?
34. Explain how an asteroid could end up hotter than the sun before hitting Earth
35. List and describe evidence that supports the model that things are made from atoms
36. Apply the atomic model to explain thermal expansion
 When the temperature of a bar of steel is increased by one degree,
what happens to its length? Compare to what happens if you increase
the temperature of a balloon filled with air. Compare to what happens
when you increase ice one degree above the melting temperature and it
becomes liquid water.
 Explain why ice contracts when heated
37. Give examples of thermal expansion in common experience
38. Apply expansion due to heating to explain how global warming causes the oceans to
rise
39. Apply the atomic model to explain the relationship between temperature and pressure
 How is pressure related to temperature in a gas?
40. Apply the relationship between temperature and pressure to common experience
 How is this related to explosions?
41. Describe entropy. Describe an example of increasing entropy (no need to
demonstrate)
42. Describe the 2nd Law of Thermodynamics
43. Explain why converting heat energy to kinetic energy is much harder than converting
kinetic energy to heat energy
 Which is easier: converting kinetic energy to heat or converting heat
to kinetic energy? Or is it equally easy? What laws of
thermodynamics apply? What has this to do with order and disorder?
44. Apply the definition of efficiency to quantitatively compare power used and useful
power
Unit 3: Force and Gravity
45. Define and list the units (and convert among common units) for:
a) Force
b) Acceleration
c) Momentum
d) Velocity
46. Distinguish between velocity and acceleration
47. Identify and describe Newton's three laws of motion
48. Determine whether there is a net force on an object based on a description of the
object's motion
 If an object travels at a constant velocity (zero acceleration), what can
you conclude about the NET force on the object?
 If you are driving a car in a straight line at constant speed, what is the
net force on your car? Given you answer, why do you need to use your
engine at all?
49. Describe and predict the motion of an object subject to a net force
 What is the relation between the direction of the force and the
direction of the acceleration? the direction of the velocity?
50. Apply Newton's 3rd Law (action-reaction) to real-world situations
 What does the law of action-reaction mean? Why don’t forces always
cancel because of it?
51. Explain how Newton's 3rd Law relates to conservation of momentum
52. Know how the momentum of a system depends on its mass and velocity
53. Give examples of the quantitative predictive power of Newton's laws
54. Identify limitations of the predictions of Newton's laws
55. Know the equation for the universal law of gravity, and the units for the gravitational
constant
56. Explain the physical meaning of the universal law of gravity (as an interaction), and
why it is called universal
 What is the direction of the gravitational force of one object on
another?
57. Define weight and know the equation for the (approximate) weight of objects near the
Earth's surface
58. Distinguish between "feeling weightless" and "having no weight"
 How weightless is an astronaut orbiting 200 km above the surface of
the Earth? Explain your answer.
59. Describe how a force parallel to the velocity of an object affects its motion
60. Describe how a force perpendicular to the velocity of an object affects its motion
61. Explain why an object moving in a circle at a constant speed must have a force acting
on it, and identify the direction the net force on it
62. Describe how the acceleration of an object moving in a circle with a constant speed
(uniform circular motion) depends on the speed of the object and the radius of the
circle
63. Apply uniform circular motion and the law to gravity to explain how the period of a
satellite's orbit depends on the radius of the orbit
 Why do geosynchronous satellites have to be far from the Earth?
About how long do low Earth orbit satellites take to orbit the Earth?
64. Explain why the period of certain satellites is important
65. Know the speed required to orbit the Earth near the Earth's surface
66. Know the equation for gravitational potential energy, and the approximate equation
near the Earth's surface
67. Apply energy transformations to relate changes in height to changes of speed of an
object freely moving under the influence of gravity
 As you begin to go down a frictionless slide, you drop an apple over
the side. Which reaches the ground first, you or the apple? Which has
the greatest velocity? Explain.
68. Know the speed needed to escape the Earth's gravity, and explain how to find it using
conservation of energy
 How does escape velocity depend on the mass and radius of the
planet?
69. Define air resistance and describe how it depends on the density of air, the shape of
the object, and the speed of the object
70. Define terminal velocity and explain how to calculate it using Newton's laws
 How do you compute terminal velocity (how do you derive it)? What
does the terminal velocity depend on?
71. Calculate the energy supplied by an engine to overcome air resistance in terms of the
force of air resistance and the distance traveled
72. Explain how air resistance affects gasoline consumption
 Use this explain whether it costs more gas to travel 30 mph or 60 mph
if you want to travel from Princeton to New York City.
73. Apply conservation laws to make quantitative predictions
 What is conservation of energy? Conservation of momentum? Find an
example where conservation of energy is the easiest (only?) way to
solve a problem. Find an example where conservation of momentum is
the only way to solve a problem.
 If a bomb explodes and breaks into two pieces of shrapnel in which
one is twice the mass of the other, what can you say about the
directions the two pieces travel? Their speeds? Their kinetic energies?
 When is a system's energy or momentum not conserved?
74. Define and distinguish antimatter, dark energy, and dark matter
 What is the mass and charge of an antiproton (compared to a proton)?
75. Explain what distinguishes chaotic motions, and give real-world examples where
chaos theory is important
 How is it that “they can send a man to the moon but they cannot
predict the weather”?
76. Apply proportional reasoning to all of the quantitative physical relationships above
(how one quantity scales with another quantity)
 How does kinetic energy change if you double the mass? The speed?
 Same questions for momentum.
Unit 4: Radioactivity
77. Define radioactivity
78. Know approximately how much energy (in calories) is released in the radioactive decay
of a single nucleus
79. Know the absolute and relative sizes of an atomic nucleus and an atom
80. Identify the particles that make up an atom
81. Describe the structure of an atom
82. Define atomic number and atomic mass in terms of the constituents of atomic nuclei
 What does atomic weight tell us about the nucleus? What does atomic
number tell us?
 What is an isotope? If two atoms have nuclei that are different
isotopes of the same element, how does this affect their chemical
properties? Nuclear properties?
83. Describe what happens to an atom during nuclear fission
 A nucleus decays into fission products and light mass (or zero mass)
particles. What are the possible light mass particles (should be able to
name five and know their charges)?
84. Define alpha, beta, and gamma rays
85. Apply conservation laws to explain why alpha, beta, and gamma rays are more
dangerous than the heavier nuclei that produce them
 In radioactive decay, which is more dangerous, the fission products or
the light mass (or zero mass) particles? Be prepared to explain why
using the conservation of momentum and energy.
86. Rank alpha, beta, and gamma rays according to penetrating power
 Which type of ray is easiest to stop? Which is hardest to stop?
87. Apply conservation of nucleons and conservation of charge to nuclear reactions
 To have a radioactive decay, what condition(s) have to be satisfied
about the nucleus that decays and the nuclei and rays that are produced
from the decay?
88. Explain how we know that mass is not always conserved ("conservation of mass" is a
law that has been disproven)
 What is the equation E=mc2 telling us about mass and energy?
 Why does a block of uranium have so much more energy than a
fastball? What form of energy is it? (nuclear energy is not good
enough: I mean microscopically, what kind of energy is being
converted into heat?)
89. Give examples of real-world applications of radioactivity
 If someone drinks gin, why is it important that it be radioactive?
90. Describe a chain reaction.
91. Define half-life. Given the half-life of a radioactive substance and an initial amount,
estimate how much will remain after a given interval of time.
92. Define exponential growth, and give examples
Unit 5: Waves
93. Define and list the units (and convert among common units) for:
a) frequency
b) period
c) amplitude
d) wavelength
94. Describe what a wave is, and its amplitude, frequency, and wavelength.
95. Compare the transport of mass for a projectile to the transport of energy for a wave.
 How can waves be used to send information?
96. Distinguish between transverse and longitudinal waves, and identify waves which are
neither.
97. Identify what factors do and don’t affect the speed of a wave (and under what
conditions).
98. Know and apply the mathematical relationship between speed, frequency, and
wavelength of a wave.
 Is the relation the same for all kinds of waves?
99. Draw a snapshot graph of a continuous wave if you know its amplitude, wavelength,
and speed.
100. Describe how a wave propagates through a medium.
101. Explain the importance of the "springiness" of the medium in wave propagation.
102. Describe wave reflection and give examples.
103. Define dispersion and describe what it means for a medium to be dispersive.
 If a medium is dispersive, what does that say about the speed of waves in
it?
 Compare dispersion in deep water waves versus shallow water waves.
104. Describe refraction and give examples.
105. Explain what causes a wave to refract.
106. Describe wave interference, and give examples.
 What is the interference pattern when a plane wave hits a wall with two
slits? How does it depend on the separation between slits?
107. Distinguish between constructive and destructive interference.
108. Illustrate wave interference using "movie pictures" (history plots) of waves.
109. Distinguish between intensity and amplitude of a wave.
110. Describe how a "standing wave" is created.
111. Describe diffraction, and give examples of diffraction (for both sound waves and
light waves).
112. Describe resonance, and what causes something to resonate.
113. Explain how you can combine sounds to make a beat frequency.
114. Apply a qualitative understanding of the above phenomena (reflection, refraction,
dispersion, interference, diffraction, resonance, beats) to explain observations in your
daily life.
 How does speed of shallow wave vary with depth? How is this related to
tsunamis?
 Why can you hear people across a lake at night, but not during the day?
115. Qualitatively describe what an electric field is, and identify what causes or creates
an electric field.
116. Describe the Coulomb force law between two electric charges. Know how the
force depends on the magnitude of the charges and the distance between them.
117. Qualitatively describe what a magnetic field is, and identify what causes or
creates a magnetic field.
118. Qualitatively describe effects of electric and magnetic fields on electric charges
and currents.
119. Describe an electromagnetic wave: how the direction of propagation compares to
the directions of the magnetic and electric fields, and how such a wave may be
produced by an oscillating electric charge. Sketch the pattern of electric and
magnetic fields.
 What happens to electric and magnetic fields if you move a charge? if you
move a magnet? how is this related to electromagnetic waves?
120. Describe and identify parts of the electromagnetic spectrum
 Be able to order from highest to lowest frequency: radio waves,
microwaves, infrared, visible, ultraviolet, x-rays, gamma rays
121. Given a certain frequency of electromagnetic radiation, estimate the physical size
of a detector that would detect it.
Unit 6: Quantum Physics
122. Identify experimental results that led to the quantum revolution.
123. Identify and describe five surprising observations that only are explained by
quantum physics.
124. Identify four devices or technologies that affect your daily life and that were
invented thanks to our understanding of quantum physics.
125. Define a quantum.
126. Describe Planck's Law.
127. Apply Plank's law to rank the energies of different kinds of photons (e.g. radio
waves, visible light, x-rays).
 Which has greater energy, a quantum of x-rays or a quantum of radio
waves?
128. When a metal is heated in a flame, describe how the color of the metal depends on
the temperature.
129. Sketch a qualitatively correct graph of intensity vs. frequency of light emitted
from a mental rod held in a flame. Describe how this plot contradicts the predictions
of classical physics, and how quantum physics resolved the contradiction.
130. Describe the photoelectric effect. Describe how the effect differs from the
expected results from classical physics. Describe how quantum physics explains the
actual experimental observations.
 How does the number of electrons ejected depend on color? on intensity?
131. Describe the spectrum of light emitted from hot hydrogen gas.
132. Explain how atomic spectra provide observational evidence for quantum theory.
 Why does hot hydrogen gas only emit certain discrete colors (spectral
lines)?
133. Explain how the spectrum emitted by hydrogen provides information about the
energy levels of electrons in hydrogen gas.
134. Explain how atomic spectra may be used to determine the composition of stars.
135. Describe the Bohr model of the atom, including his formula for energy levels.
136. Explain why, according to classical physics, atoms should not exist.
137. Describe wave-particle duality and give examples (how has it been observed).
 What happens when you fire single photons 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 electron goes through? How is the pattern
different if I use electrons instead?
138. Describe the Heisenberg uncertainty principle. Describe how you might "see"
this principle if Planck's constant were much larger.
 How is it related to the problem with Rutherford’s model of the atom?
139. Describe how quantum uncertainty is different from classical measurement
uncertainty.
 What does quantum physics says about determinism? What is the role of
“waves” in quantum theory?
Unit 7: Special Relativity
140. Know that Maxwell's equations imply that the speed of light is constant.
141. Using an example with two observers moving relative to each other, explain how
Newton's ideas of time and space are inconsistent with the idea that the speed of light
is constant.
142. Describe an "inertial reference frame".
143. Describe what "time dilation" means.
144. Explain how the constancy of the speed of light implies that time is relative;
specifically, the time of a moving clock is dilated.
145. Describe what "length contraction" means in special relativity.
146. Define the Lorentz factor. Compute  given a relative velocity between two
observers.
147. Apply time dilation to compute the time between two events for different
observers moving with different speeds.
 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? Who is right?
148. Apply length contraction to compute the distance between two events measured
by different observers moving with different speeds.
 If gamma =10, and we each have identical clocks: 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?
149. Explain the relativity of simultaneity, and give an example of simultaneous events
in one reference frame that are not simultaneous in another reference frame.
150. Explain the twin paradox, and its resolution.
151. Explain the paradox of the "pole vaulter and the barn", and its resolution.
152. Explain the relevance of special relativity to muons hitting the Earth.
153. Know what quantities are constant and what quantities are relative in special
relativity (e.g. x, t, c, p, E, m, c2t2-x2).