Duke University
Department of Physics
Physics 105
Spring Term 2012
HOMEWORK 0
Available: January 11
Due: January 13, by email.
Problem 1: Introduce Yourself
By Friday, please send me an email (schol@phy.duke.edu) introducing
yourself, indicating:
Your ma
Duke University
Department of Physics
Physics 105
Spring Term 2012
HOMEWORK 2
Available: January 23
Due: February 3, at the beginning of class.
Reading: Ryden & Peterson Ch. 2.5, Ch. 3.1-3.3
Problem 1
Explicitly show Keplers third law, P 2 =
plers rst and
Duke University
Department of Physics
Physics 105
Spring Term 2012
HOMEWORK 3
Available: February 6
Due: February 13, at the beginning of class.
Reading: Ryden & Peterson Ch. 5, except 5.5
Problem 1
Ryden & Peterson 5.3
Problem 2
Ryden & Peterson 5.5
Prob
FREQUENTLY ASKED QUESTIONS
February 20, 2012
Content Questions
How do you nd the center of mass?
The position of the center of mass of a system of N masses is given by
N mi ri
i=1 M , where ri are the positions of the masses with respect to some
origin. I
FREQUENTLY ASKED QUESTIONS
February 8, 2012
Content Questions
How do we use the formula I , where its all dierentials?
The formula for I , the specic intensity, is a distribution (sometimes called
a dierential distribution): this is a very important kind
FREQUENTLY ASKED QUESTIONS
February 6, 2012
Content Questions
What is ? What is the dierence between and S ?
The quantity is known as the cross-section: its a measure of the probability that a photon will be absorbed by an atom. (The cross-section quantit
FREQUENTLY ASKED QUESTIONS
February 3, 2012
Content Questions
In the slide with the orbital distributions we saw, there were 5
columns, s, p, d, f. I thought the rst four L states were s,p,d,f.
Where did the e come from?
Hmm, you are right, thats odd. Im
FREQUENTLY ASKED QUESTIONS
January 23, 2012
Administrative Questions
Can you do examples with numbers?
Ill typically not plug in numbers, and Ill also often skip standard algebra and
computation steps that I know you all know how to do, as students usuall
FREQUENTLY ASKED QUESTIONS
January 18, 2012
Administrative Questions
Will there be a formula sheet for this class?
For the midterm and nal exams, you will make your own formula sheet.
Content Questions
Why do we need to observe stellar parallax in order t
FREQUENTLY ASKED QUESTIONS
January 11, 2012
Administrative Questions
Will we be following the order of the text or skipping? Is there
any material we will cover outside of it?
I will follow approximately the order of the text, although we will skip some
m
Metric Conversions Worksheet 1. 0.75 kg to milligrams
2. 1500 millimeters to km
3. 2390 g to kg
4. 0.52 km to meters
5. 65 kg to g
6. 750 micrograms to g
7. 0.25 megameters to cm
8. 23.8 fg to kg
9. 2.77 kg to mg
10. 2.90 cm to terameters
11. 45.6 microli
Name: _ Hour: _ Date: _
Physics: Scientific Notation
Part A: Express each of the following in standard form. 1. 5.2 x 103 2. 9.65 x 104 3. 8.5 x 102 4. 2.71 x 104 5. 3.6 x 101 6. 6.452 x 102 7. 8.77 x 101 8. 6.4 x 103
Part B: Express each of the following
Scientific Notation and Unit Prefixes
Make the following conversions: 1) 3.4 liters to milliliters 6) 45 meters to centimeters
2)
876 millimeters to meters
7)
11.7 grams to kilograms
3)
78,999 milligrams to grams
8)
0.0009 kiloliters to liters
4)
0.9 cent
FREQUENTLY ASKED QUESTIONS
February 10, 2012
Content Questions
Im unclear on the variance: is the width of the distribution 2 or
?
The variance is 2 , and the standard deviation is , the square root of
the variance. The integral of a Gaussian going from t
FREQUENTLY ASKED QUESTIONS
February 13, 2012
Content Questions
What exactly does metallicity for a star mean?
Astronomers call any element with Z 3 a metal, whether or not it
really can exist in metallic form. Astronomers use the word metallicity
to mean
Duke University
Department of Physics
Physics 105
Spring Term 2012
CLASS PROJECT INFORMATION
For this class, you will need to complete a project on an astrophysicsrelated topic of your choice. The class project is worth 20% of your grade
(bonus points are
Thermal Radiation
All objects with temperatures above
absolute zero emit electromagnetic radiation
Also called
'Blackbody'
radiation:
it's what
you see
emitted
even with
no reflected
light
(black object)
The spectrum depends on temperature
- Hotter object
Orbitals calculable with QM
Interaction of Light with Matter
Photons emitted or absorbed as
electrons jump levels
Happens
only at specific
energies
(frequencies)
for a given
substance
emission lines
absorption lines
Kirchoffs Laws
Examples of Spectra
Emis
Duke University
Department of Physics
Physics 105
Spring Term 2012
HOMEWORK 5
Available: February 20
Due: February 27, at the beginning of class.
Reading: Ryden & Peterson Ch. 7.1-7.2, Ch. 8
Problem 1
Ryden & Peterson 7.2
Problem 2
Ryden & Peterson 7.3
Pr
Duke University
Department of Physics
Physics 105
Spring Term 2012
HOMEWORK 4
Available: February 13
Due: February 20, at the beginning of class.
Reading: Ryden & Peterson Ch. 6
Problem 1
Ryden & Peterson 6.1
Problem 2
Ryden & Peterson 6.4
Problem 3
Ryden
Duke University
Department of Physics
Physics 105
Spring Term 2012
HOMEWORK 1
Available: January 11
Due: January 23, at the beginning of class.
Reading: All of Ch. 1 of Ryden & Peterson.
Problem 1
Ryden & Peterson 1.2
Problem 2
Ryden & Peterson 1.3, but c
FREQUENTLY ASKED QUESTIONS
February 15, 2012
Content Questions
How do you determine the mass of a planet if there are no moons?
If a planet has a natural moon, and assuming the mass of the moon m
is less than the mass of the planet such that m < Mp , one
Graphing Motion Assessment
Use the graph of position versus time for a projectile (found on the next page) to complete the following:
1.
From the position vs. time graph on the next page: a. Find the time at which the speed is a minimum
b.
Find the minimu
Graphing Motion Assessment for AP-B
Use the graph of position versus time for a projectile (found on the next page) to complete the following:
1.
From the position vs. time graph on the next page: a. Find the time at which the speed is a minimum
b.
Find t
Magnetic Fields, Magnetic Forces, and Electromagnetic Induction Sample Problems
1. A wire 1 m long carries a current of 5 A. The wire is at right angles to a uniform magnetic field. The force on the wire is 0.2 N. What is the magnetic field strength? 2. N
Magnetic Fields and Forces Homework
1. A wire 0.10 m long carrying a current of 2 A is at right angles to a magnetic field. The force on the wire is 0.04 N. What is the strength of the magnetic field? What would its strength be if the wire is at an angle