LECTURE 1
Welcome to Physics I !!!
Prof. Wasserman
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Outline
•
•
•
•
Why Physics?
Course organization
Course grading
Chapter 1
– Significant figures
– Units
– Estimating
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Why Physics?
• Students in this course come from diverse backgrounds
and are heading in diverse directions
• Physics provides all with a scientific toolbox
– Physics describes the fundamental operation of the world around
us: Engineering, Chemistry, Biology, Astronomy, etc.
– Teaches us how to approach complex problems
• Science is inherently progressive
– If approached correctly, we can all contribute!
• What you are going to do matters!
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Physicists look at the world differently
• This class will attempt to show you how we
understand the world around us
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Course Organization
• Everything you need to know about the course can be
found on the course website:
http://faculty.uml.edu/dwasserman/95.141.htm
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Course Communication
• Website
– http://faculty.uml.edu/dwasserman/95.141.htm
• Physics I Twitter account: @UMLPhysicsIS10
• On Facebook, search for "UML Physics I S2010"
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Course Organization
• Physics I meets 4 times a week
– Lectures
• 2:30-3:20 MW, OH 150
– Recitation Sections
• Varying times, locations
• Know your instructor and section number!!!
– Homework review sessions
• 6:30-9:30 pm, OH 218
• Held every week before HW is due
• Textbook: Giancoli: Physics for Scientists and
Engineers, 4th Ed.
• NO LAB THIS WEEK!!
• RECITATION SECTIONS THIS WEEK!!
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Lecture Organization
• Exam Prep. Problem
• Review of Previous Lecture
• Lecture Main Topic
– Will include clicker questions
– Example problems
• Symbolic
• Numerical
– Movie clips
– Demonstrations
• Summary
• LECTURES MOVE FAST!!!
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Lectures
• NO COMPUTERS IN LECTURE!!
• NO CELL PHONES!!
• NO TALKING!!
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Recitation Section Organization
• Lecture Summary
• Example problems from Book
• Quizzes
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Course Grading
Item
Standard HW
LP HW
Quizzes
Participation
Exam 0
Exam 1
Exam 2
Exam 3
Final Exam
Total
Points
90
20
90
30
20
100
100
100
200
750
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Range
>600
Grade
A
560-599
490-559
450-489
B+/AB
C+/B-
375-449
340-374
265-340
<265
C
D+/CD
F
PRS Clickers
• For detailed info on setting up PRS clickers, go
to:
http://clickers.wiki.uml.edu/Student+Resources
• You must have your own clicker!!
– You cannot borrow a friend’s clicker for class
– You may not have more than 1 clicker in class: this is
academic fraud.
• Clickers will be used to determine part of
participation grade
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Let’s Set-Up Our PRS Clickers
A.
B.
C.
D.
E.
F.
Power on your clicker
When autoscan begins, press * to stop it
Press * to display the Setup Menu
Scroll up to display the ID: menu option
Press enter (green arrow) to select it
Input your Student ID: No Alpha Characters, No
Leading Zeros!!!
Press the left arrow to backspace if you make an error
G. If correct, press enter (green arrow) to save your
Student ID
H. You may shut off the PRS or Press * and enter (green
arrow) to scan for classes
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
PRS Example
• Enter class letter (or number): then “enter”
• Question: In order to do well in Physics I, you
should spend how many hours working on
Physics I material for every hour in class
(recitation and lecture)?
–
–
–
–
A) 0-1 HRS
B) 1-2 HRS
C) 2-3 HRS
D) 3+ HRS
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Standard Homeworks
• Homework assignments online at course website
(http://faculty.uml.edu/dwasserman/95.141.htm)
• Most weeks, the written HW is due on Friday (there are 2
weeks when the HW is due Wed.).
• There will be a box in the Physics front office where you
can turn your HWs in. HWs will be returned in section
within ~1 week.
• HWs must have NAME and SECTION # !!!
• Please follow the HW guidelines in the syllabus.
• Graded out of 10, total 90/750 of your final grade
• Late homeworks not accepted.
• Homework review sessions for EVERY homework set.
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Lecture Prep Homeworks
• These HWs are designed as review of the previous lecture,
and are due before each lecture.
• Usually consist of 2-3 tutorials. You have unlimited attempts
to answer.
• Use these as a study guide to keep you up to speed with
lectures.
• Count for 20 pts over the course of the semester
• DONE ONLINE!!!!
• www.masteringphysics.com
– Course “WASSERMANS10”
• Instructions can be found on website for accessing
masteringphysics.com
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
www.masteringphysics.com
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
www.masteringphysics.com
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Quizzes
• Given by recitation instructor, during recitation.
• 90/750 of Final Grade.
• No remakes. (for excused absences, recitation
instructor can drop missed quiz).
• Normalized to class quiz average (a tough
recitation instructor doesn’t hurt your final
grade!)
• Should cover material from previous week’s
class/recitation.
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
EXAMS
• 3 Mid-Term Exams
– Each worth 100 pts.
– Taken in class.
– Each covers lectures from previous exam up to exam
date
– No rescheduling
– Extra time available for students with disabilities
(must have note from Office of Student Disabilities)
• Final Exam
– 200 pts.
– Date/Time/Location To Be Announced
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
EXAM 0
• There will be an Exam 0 in class on Wednesday.
• Exam 0 counts for 20 pts.
• This is a test of very basic math skills and the
contents of Lecture 1 and Chapter 1.
• This is meant to be a tool for you
• It will give you a chance to see where your
quantitative skills stand, to see whether you are
prepared for this very challenging course.
• The difficulty level of Exam 0 is not indicative of
the types of exams I give!!
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Department of Physics and Applied Physics
Physics I Resources
• Need to get help as soon as you feel like you
may be falling behind!
• The first person to contact if you are having
problems with Physics I is your Recitation
Instructor!!
• Recitation Instructors will have office hours each
week during which they can meet.
• HW review sessions
• UML tutoring center: information on course
website
(http://faculty.uml.edu/dwasserman/95.141.htm)
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Fun ≠ Easy
• We have worked very hard to make this course
fun and interesting!
• But this does not mean the course will be easy.
• This stuff matters!!
• 1hr in class = 3+ hrs outside of class
• You will have to work hard to do well in Physics I.
• You will have to be organized to do well in
Physics I.
• You will have to come to class to do well in
Physcis I.
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Physics I (95.141)
Lecture 0: Online
Basic Trig., Calc. and other
mathematical concepts.
Lecture 1: Chapter 1
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Chapter 1-3: Measurement and Uncertainty
• No measurement is perfectly precise
– For any measurement, it is important to give the
uncertainty in the measurement
• Either in absolute numbers: 0.1g or 0.2mm, for example
• Or in percentage: 10m +/- 2%, or 3.2kg +/- 10%
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Chapter 1-3: Measurement and Uncertainty
• If uncertainty is not explicitly mentioned, we
assume it to be 1, or a few units in the last digit
specified
– “The speed of the car was 51.2 mph”
Means…
– “The speed of the car was 51.2 mph +/- ~0.1mph”
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Significant Figures
• Significant figures: the number of reliably known
digits in a number
– 45.21 kg  4 significant figures
– 0.00495m  3 significant figures
• If you are making a measurement, be careful
about how many digits you use!!
– i.e. I am 6 ft 4.23457 inches
• Scientific Notation
– 4,560,000,000  4.56 x 109
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Chapter 1-4: Units
• Units are important!!!
• If I am bragging about my weight:
– “I weigh 150!”
Could mean:
– “I weigh 150lbs”
Or….
– “I weigh 150kgs”
• In Physics we try to use the same set of units:
SI: Système Internationale
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Chapter 1-4: SI Units
• Length: meters [m]
• Time: seconds [s]
• Mass: kilogram [kg]
• Temperature [K]
For dealing with very small or very large numbers, we can
make use of prefixes:
Ggiga109
Mmega106
Kkilo103
mmilli10-3
µmicro10-6
nnano10-9
• 100,000m can also be written as 100 kilometers (km)
• 0.0001s could be written as 100 microseconds (µs)
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Chapter 1-4: Converting Units
• Sometimes we don’t get problems in the units
we like…
– Two cars are traveling on the highway, car 1 at
55mph, car 2 travels 200m in 10s. Which is going
faster?
– Need to convert between mph and m/s  conversion
factor
– Car 1
24.81 m s
– Car 2
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
20 m s
Chapter 1-6: Estimating
• Why is estimating important?
 sand  1.6 g cc
 gold  19.3 g cc
m goldhead
Vgoldhead
Vsandbag

 goldhead
m sandbag
 sandbag
 goldhead 19.3


 12
 sandbag 1.6
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Chapter 1-6: Estimating
• Being able to make order of magnitude
estimates is an important skill!!
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
x  13.5m
h  15m
Chapter 1-6: Estimating (Fermi Problems)
• What is the capacity of this room?
• Could try to count every chair
• Or could make a quick estimate…
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Chapter 1-6: Estimating (Fermi Problems)
• How many barbers/salons should a town of
300,000 people have?
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
Chapter 1-7: Dimensional Analysis
• Dimensions of a quantity refer to the units that make it
up
– Speed  L/T, i.e. [m/s]
– Acceleration  L/T2, i.e. [m/s2]
• We can learn a lot simply by looking at the units involved
in an expression.
If someone tells you that the speed of a car is given by the
following expression:
v  A  mass / time with
[kg]
[ v ]  [ m] 
 kg  m / s
[ s]
95.141, F2009, Lecture 1
Department of Physics and Applied Physics
A[m]
Chapter 1-7: Dimensional Analysis
• Later in the semester, we will learn that Force has the
units of Newtons [N]
• F=ma
• Fg=GM1M2/R2
• What are the Units of G-Universal Gravitational
Constant?
95.141, F2009, Lecture 1
Department of Physics and Applied Physics