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Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
CHOWDHURY 95.141 PHYSICS I SPRING 2013 LECTURE 1
95.141
Welcome to Physics I Andriy Danylov
http://faculty.uml.edu/Andriy_Danylov/Teaching/PhysicsI/
Course Website
http://echo360.uml.edu/danylov2013/physics1fall.html
Lecture (video)
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Today’s Agenda
Course details
Website
Organization
Textbook
Homework
Mastering Physics
Grading
Tutoring
Exams
Chapter 1
Measurement
Uncertainty
Significant figures
Units
Conversions
Estimations
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Clickers
You need to register your clicker online at
http://www1.iclicker.com/register-an-iclicker using the code
found on the back of the clicker, and your university ID number.
You must return your clicker at the end of the semester
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Clickers
• You can answer questions posed by the
lecturer with a clicker
• You must have your own clicker!! o You cannot borrow a friend’s clicker for class
o You may not have more than 1 clicker in class: this is academic
fraud.
• Clickers will be used to determine class
participation
• Clickers will be used from next week!!
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Course Website
Everything you need to know about the course can be found on the course website:
http://faculty.uml.edu/Andriy_Danylov/Teaching/PhysicsI/
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Course Organization
Physics I meets 4 times a week
• Lectures : 9:00-9:50 MW, Olney 150
• Recitation Sections
Various times (M/W or Tu/Fr) and locations
RECITATIONS MEET THIS WEEK Wed and Fri !
LABS MEET NEXT WEEK!
Text: Giancoli: Physics for Scientists and Engineers, 4th Ed.
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
• New topics ahead of recitations
• Clicker questions
• Example problems
• Movie clips
• Demonstrations
Lecture slides will be posted on-line
Lecture recording (video and audio) will be posted:
Lectures
http://echo360.uml.edu/danylov2013/physics1fall.html
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Recitations • Lecture review (5-10 min)
• Example problems from
the textbook
• Quizzes
(weekly, 10 min)
• Written HW
(collected and graded)
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Weekly Homework
• ALL HW is on www.masteringphysics.com
Course: “95141Fall2013”
Course ID: MPDANYLOV44541
• The online HW is typically due on Sunday at 6 pm.
(You are penalized 25% for each day late)
• Weekly HWs count for 100 points/750
(80 online, 20 written).
• Recitation instructors will collect written homework weekly.
• Homework assignments are available at course website
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
www.masteringphysics.com
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Recitation Quizzes Given by recitation instructor, during recitation.
100/750 of Final Grade.
Typically covers material from previous week’s
class/recitation and homework.
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
MATH DIAGNOSTIC QUIZ
• Given in your first recitation.
• This is a check of very basic math skills.
• Meant to be a diagnostic tool for you & us.
• See where your quantitative skills stand.
• See if you are prepared for this very challenging
course.
10 points for all for just taking it.
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Physics I Resources
• Get help early and often.
• The first person to contact with problems in Physics I is your Recitation Instructor!!
• Recitation Instructors will have office hours each week during which they can be met.
• Physics Department Tutoring Center: Tutors are available free of charge in the Physics Department tutoring room (9 am-5 pm), located adjacent to the Department office on the 1st floor of Olney Hall.
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
EXAMS
3 Mid-Term (in-class) Exams
Each worth 100 pts.
Covers incremental material from previous exam
No rescheduling
(Extra time available for students with note from Student Disability Services)
Final Exam 200 pts (in-class) .
Date/Time/Location To Be Announced
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Course Grading
Item Points
Class Participation 40
Weekly HW 100
Quizzes 100
Math Quiz 10
Exam 1 100
Exam 2 100
Exam 3 100
Final Exam 200
Total 750
Range Grade
>80% A
75-80% A-
70-75% B+
65-70% B
60-65% B-
55-60% C+
50-55% C
45-50% C-
40-45% D+
35-40% D
<35% F
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Introductory Physics
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Measurement and uncertainty
There are 3 parts to a measurement:
1)The measurement (13.2)
2)The unit (g)
3)The uncertainty (±0.4)
(No measurement should be written without all three parts)
NO measuring device can give perfect measurements
without experimental uncertainty.
Convention: If uncertainty is not mentioned,
13.2 g is said to have an uncertainty of ±0.1 g (Which means we are reasonably sure the actual weight is somewhere
between 13.1 and 13.3)
13.20 g
13.200 g (uncertainty ±0.01g) (uncertainty ±0.001g)
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Percentage uncertainty
SO, the uncertainty in the measurement can be provided
• either in absolute numbers: e.g. 0.1g
• or as a percentage: 13.2g +/- 0.7%
The percent uncertainty is the ratio of the uncertainty to the measured value, multiplied by 100
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Significant Figures (SF)
The accurately known digits in a number plus one
uncertain digit are called its significant figures.
Two accurately known digits
One uncertain digit
SF=2+1=3 13.4 g
Three accurately known digits
One uncertain digit
SF=3+1=4 13.40 g
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Number of SF rules
1. All nonzero digits are significant
2. Leading zeros to the left of the first nonzero digit
are not significant
3. Trailing zeros that are after the decimal point are
significant
0.001 m
0.012 m
0.001m= 1*10-3 m=
1.234 m
3.07 m
3.20 m
0.0320 m
Reason? 1mm (definitely SF=1)
SF=3 SF=3
SF=4
SF=3
SF=1 SF=2
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Number of SF rules (cont.)
4. When a number ends in zeros that are not to the
right of a decimal point, the zeros are not
necessary significant.
Here, there is an ambiguity:
length=2950 m, SF may be 3 and 4 ? To avoid ambiguity powers-of-10 notation is used
(reasonable convention):
If you mean that SF=3, write 2.95x103 m
If you mean that SF=4, write 2.950x103 m
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Addition/Subtraction/Multiplication/Division
• In addition/subtraction, the final result is no more precise than
the least precise number used to get the answer.
• In multiplication/division, any number of the problem with the
least number of SF determines the number of SF in the
answer.
82 kg + 0.13kg = Least certain
82.0kg + 0.13kg = Least certain
82.00kg+0.13kg = Both equally certain
82.000kg+0.13kg= Least certain
3.0 x 12.60 =
82.13kg
=82.1kg
82.13kg
82.13kg
37.80 = 38 (SF=2) (SF=4)
82 kg + 0.93kg = 83kg =82kg 82.93kg
82.13kg
(SF=2 should be)
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Units
• Units are important !
– “It weighs 5 “ ? Could mean:
– “It weighs 5 ton”
Or….
– “It weighs 5kg”
• In Physics we try to use same set of units:
SI: Système Internationale
5 ton 5 kg
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
SI units (cont.)
• Length: meters [m]
• Time: seconds [s]
• Mass: kilogram [kg]
• Temperature [K]
For very small or very large numbers, use prefixes:
Ggiga109
Mmega106
Kkilo103
mmilli10-3
µmicro10-6
nnano10-9
• 100,000m can also be written as 100 kilometers (km)
• 0.0001s could be written as 100 microseconds (µs)
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Converting units
Very often we have to convert a quantity in a certain unit to its equivalent
in a different unit of the same kind.
In this case, we use the fact that multiplying anything by 1
doesn’t affect its value:
Example: Convert 30mile/h to m/s
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
Example: calculating the distance
to a lightning strike
Estimating
Being able to make order of magnitude estimates is an important skill!!
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
What is the weight of the earth?
Estimating
Department of Physics and Applied Physics 95.141, Fall 2013, Lecture 1
The End
See you on Monday