2 Jan: The grade list has been removed.
19 Dec: Grades are posted on Leo Online as of 15:00.
16 Dec: The circumference of a circle is 2 * pi * r. It is NOT pi*(r)^2!!!!!!
22 Nov: The marvels of magnetism can be found with
the Perfect Sommelier guaranteed to age wines in only 30 minutes
using a magnetic field and you pay only $35. If you don't believe
this, the device was
carefully tested by wine experts (with the expected results).
22 Nov: Here is another sample final and its answers.
22 Nov: I am posting sample final exams early for students who
requested them. A sample final is here and the answers are
here.
3 Nov: Sample test 2 is here and the solutions are here.
29 Sept: The first exam will be Friday, Oct 7, in class. It will cover chapters 1-6. Here are some sample tests: sample test1only covers chapters 1-5. This test was given in 2002 and covers all 6 chapters. Here are the answers to the 2002 test.
Here are some tips on getting a good
grade (Word format) (text format) in Physics 101 from
a former student .
Privacy Concern: If you do NOT want other people to be able
to see your homework grade when it is returned, let me know. I will
assign you an ID number to use on your homework instead of your name.
Syllabus (updated
8/23/05)
Please note that the textbook has four different kinds of problems: Projects, "1-step", Exercises and Problems.
| Homework Set |
Due Date |
Projects | 1-Steps | Exercises | Problems | Other (Extra Credit) |
Solutions |
| 1 | Sept 9 | Chap 2: 6, 14, 16, 22, 26, 28, 48 | See Chapter 1 Problems |
Estimation 1 See below. |
here | ||
| 2 | Sept 16 | Chap 3: 4, 12 Chap 4: 4, 8 |
Chap 3: 4, 16, 18, 34 Chap 4: 6, 10, 26, 28 |
Chap 3: 4, 8, 9 |
Estimation 2 see below |
here |
|
| 3 | Sept 23 | Chap 5: 1 | Chap 4: 30, 32, 50 Chap 5: 4, 18, 20, 22, 36 |
Chap 4: 6 Chap 5: 2, 4 |
Estimation 3 see below |
here | |
| 4 | Sept 30 |
Chap 6: 2, 8 | Chap 6: 4, 8, 12, 24, 28, 44, 48 | Chap 6: 2, 4, 6 | Estimation 4 see below |
here | |
| none | Oct 7 | ||||||
| 5 | Oct 14 | Chap 7: 2, 4, 10 | Chap 7: 4, 16, 24, 26, 28, 38, 44, 50 | Chap 7: 4, 6 | Estimation 5 see below |
here | |
| 6 | Oct 21 | Chap 8: 4 | Chap 8:2, 4 | Chap 7: 60, 68 (plus extra below) Chap 8: 2, 4, 12, 18, 26 |
Chap 8: 2 (plus extra below) |
Estimation 6 see below |
here |
| 7 | Oct 28 | Chap 8: 6 Chap 9: 5, 6 |
Chap 8: 38, 44, 52, 57 (see hint below), 58 Chap 9: 2, 10, 14 |
Chap 8: 6 (and one more below) |
Estimation 7 see below |
Here | |
| 8 | Nov 4 |
Chap 9: 16, 18, 28, 36, 40 Chap 10: 16, 18, 22, 46 (and one more below) |
Chap 9: 4 (and one more
below) Chap 10: 6 |
Chap 9: Prob 6 |
Here | ||
| none | Nov 11 |
||||||
| 9 | Nov 18 | Chap 22: 2 | Chap 22: 6, 8, 10, 12, 14, 24, 32, 50, 54 | Chap 22: 2 |
Estimation 9 see below |
Here | |
| none |
Nov 25 |
Thanksgiving1 | |||||
| 10 | Dec 2 | Chap 23: 4, 6 |
Chap 23:6, 10, 14, 18, 20, 22, 24, 30, 40, 44, 60 | Chap 23: 6 | Estimation 10 see below |
Here | |
| 11 | Dec 9 | Chap 24: 4, 8, 16, 24, 32, 34, 36 Chap 25: 2, 12, 16, 18, 24, 26, 34, 44 |
Chap 25: 2 |
Estimation 11 See below |
Here |
Does the KE of a car change more when it does from 15 to 30 mph or
when it goes from 30 to 45 mph? (In other words, does it take
more energy to increase your speed from 15 to 30 mph or
from 30 to 45 mph?)
Chapter 8 extra problem (HW set 6):
Neglect the weight of a meter stick and consider only the two weights hanging from its ends. A 3 kg weight hangs from one end and a 6 kg weight hangs from the other. Where is the center of mass of this system (the point of balance)? How does your answer relate to torque? (Hint: This is the same as Problem 3, but with the numbers changed.)
Chapter 8 extra problem (HW set 7):
Extra 1: An astronaut with a mass of 70 kg is in a space station rotating to give him the same weight as on Earth. What is the weight of the astronaut (in pounds) on the Earth? Something goes wrong and the rotational velocity of the space station doubles. What is the apparent weight of the astronaut now (in pounds)?
Hint for Chapter 8, exercise 57: The phrase 'How does the wheel respond' means 'Does the wheel rotate? If so, in which direction does it rotate?'
Chapter 9 extra problem:
Do chapter 9, problem 5 for the space shuttle when it is 300
kilometers above the Earth's surface.
Chapter 10 extra exercise:
Suppose that you drop an object from an airplane travelling at constant
velocity and further suppose that you can ignore air resistance.
a) What will be its falling path (ie: its trajectory) as observed by someone
at rest on the ground but off to the side where they have a clear view
of the plane and object? (Draw a picture to show your answer.)
b) What will be the falling path as observed by you looking downward from
the airplane? c) Where will the object strike the ground relative
to you in the airplane?
Estimation problems are designed to help you understand the difference
between and a million and a billion and to help you get comfortable with
large numbers (ie: exponents). We consider questions like this in
daily life and in politics all the time. Is a $500 billion deficit
a lot? Is 1000 dead Americans in Iraq a lot? Should I buy a
lottery ticket? How much impact does my household trash have on the environment?
These are questions where you will need to supply some of the information
(ie: estimate). For example, in the first question, you need to
estimate the thickness of a card. Your answer should almost never
have more that one significant figure (that's the number before the 10^x)
because your estimate will never be that accurate.
Sample question: How far could you walk in a year?
Sample answer: I walk about 3 miles per hour. If I walk 12 hours
per day and 365 days per year then I can walk
3 mi/h * 12 h/day * 365 day/yr = 13140 mi/yr = 1
* 10^4 mi in one year
Note that 13140 mi is wrong because it implies that you know the answer
much better than you actually do. The 3 mph might be 2.5 or 4. The
12 hours/day might be 8 or 14. You might have to take some days
off. 1*10^4 implies that the answer is not very precise.
Chapter 1 Estimation: Your chance of winning MegaMillions is about 1 in 10^8 (ie: one in one hundred million). This is the same probability as drawing the only correct card from a deck with 10^8 cards. If you stacked 10^8 cards in a single pile, how tall would that pile be (in meters)? Which distance is this closest to: a) a tall building (100 m), b) a small mountain (1000 m), c) Mt Everest (10,000 m), d) the height of the atmosphere (10^5 m), e) the distance from here to Chicago (10^6 m), f) the diameter of the Earth (10^7 m), g) the distance to the moon (4x10^8 m)?
Estimation 2: What is the average
speed of a child's growth from birth to age 20? Express your answer in
a) inches per year, b) m/s, and c) miles per hour.
Estimation 3: How much force does your car's engine exert when you accelerate from 0 to 30 m/s (60 mph) as quickly as possible? How many people would it take to exert that much force? (Hint: estimate the acceleration first, then the force required.) (Note: ignore the fact that people can't run at 60 mph.)
Estimation 4: Estimate the momentum of a drifting continent. (Hint: you can estimate the speed of the continent from knowing that the Atlantic Ocean opened up to its present width over the last 100 million years.) Express your answer in standard units (kg-m/s).
Estimation 5: Estimate and compare the kinetic energies of a) a drifting continent, b) a pitched baseball, and c) an 18-wheeler truck driving down the highway. (Hint: look at the solutions to last week's estimation problem.) Express your answers in Joules.
Estimation 6: In the movie Spiderman II, Spiderman stops a runaway New York City subway train by attaching his webs to nearby buildings and pulling really hard for a long distance. Assume that the subway train has 6 cars, each of which has about the same mass as an 18-wheeler truck. Assume that he exerts the force over a distance of 1 km. How much force does he have to exert to stop the subway train? Give your answer in Newtons and in tons (1 ton = 10^4 N). How does this compare to the force that you can exert? (Hint: estimate the kinetic energy of a subway train at normal speed, then figure out the work needed to stop the train, then figure out the force needed.)
Estimation 7: The sun rotates on its axis approximately once a month. If the sun shrinks and becomes a neutron star, its density would increase from about 10^3 kg/m^3 to 10^17 kg/m^3 (remember that mass = density * volume). a) By what factor does the rotational inertia, I of the sun change? (You may calculate the current I and the new I and take the ratio of the two.) b) How much time will the sun take to rotate once around its axis when it is a neutron star? Give your answer in seconds.
Estimation 10: How much total electric current is flowing in all American households at 7:00 PM on a Thursday? Hint: you will need to know how many households there are in the US (the US population is 3*10^8). Another hint: consider how much electrical power each household uses and how power is related to current.
Estimation 11: Your computer's disk drive holds 100 GigaBytes of data (that's 10^11 Bytes = 8*10^11 bits). The bits are encoded on the disk drive by small regions that are magnetized in one direction or another (eg: either up or down). How large a region does it take to encode one bit of data? Express your answer in square meters (m^2). If each region is a square, how long is the side of the square? (If the square is 9 m^2 then the side of the square is 3 m. If the square is 0.01 m^2 then the side of the square is 0.1 m.)