Physics 218
Lecture 1:
Introduction
Alexei Safonov
Today Lecture
• Structure of the class
• Organizational issues
– Instructors, textbooks, meeting times
• Course requirements and grading
• Practical details
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–
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Exams
Homework and quizzes
Reading assignments
Recitations
Physics 218: Basics
• Content:
– Introduction to Classical Mechanics
– Concepts, Problem Solving, and Labs
– Requires high school level calculus
• Structure:
– Lecture (2 per week) – MPHY203 (here)
– Recitation (1 per week)- MPHY335 or 336
– Lab (1 per week) – MPHY 234 or 233
Instructors
• Lectures (MPHY 203, MW 4:10pm):
– Alexei Safonov (me)
– Email: safonov@tamu.edu
• Put PHYS218 first in the Subject line!!!
– MIST M319, 979-845-1479
• The “tower” portion of the Physics Building
– Office hours: M 2:30-4:00 PM
• Tentatively, likely to change
• Recitation and labs:
– TA’s will provide contact info at your first meeting
– First meeting already this week
eCampus
• Your main starting point, everything else is
linked to it
Lecture notes
• Link for lecture notes:
– http://people.physics.tamu.edu/safonov/218/
– I will also add a link to it in ecampus
• Another exceptionally (!) useful site:
– http://physics218.physics.tamu.edu/
Syllabus
• On my web-site, will also appear in howdy
and ecampus
Co-Requisites
• MATH 151
– It is a GOOD idea to take it before this class
– If you do well in MATH 151, you will survive
here too, but you are in somewhat
disadvantaged position as many of your
classmates took calculus in high school
• Gauge yourself:
– A lot of math in the first week (quizzes,
reviews, checkpoints) – a great opportunity to
assess your situation
• If you can relatively easily get 80+% right, you ok
• If not, consider coming back next semester
PHYS-218
• An “inverted” course:
– Heavily interactive with the material reviewed under
different angles
• Pre-lectures, lectures following up on your pre-lecture
performance, interactive recitations with content-reach
problems
– Research shows substantially increased learning
outcomes compared to standard courses
• Third time it is offered at TAMU
• A common course with common practices:
– Grade determined by your performance compared to
everyone else in PHYS-218 (well over 1,000 people)
– Unified grading policy across the whole course
How It’s Meant to Work
• You: go over online pre-lectures, do quizzes (part of prelectures), read material of the chapter BEFORE the lecture
– You should have pretty good grasp of the material when you come
here at conceptual level and have already done at least some
problems
• Me: in lecture I focus on fixing typical misunderstandings
and misconceptions and help you learn how to think “right”
– Still heavy focus (50-60%) on conceptual understanding, but about
40% practical examples (incl. problems) demonstrating concepts
• You: Do homework problems until you can do almost any
problem in the book
– Most of you will struggle in the beginning, but if you keep pushing
you will start “getting it” and there is no other way really
• Recitations: focus on solving challenging problems, help
with remaining challenges
Materials
• Get them right now or the bookstore may
run out of them:
– Buy and Register your clicker ASAP!
– Register for Modified Mastering Physics ASAP!
• MP packet comes with new textbooks or loose-leaf
book options, also available separately in the
bookstore, also can pay online (via eCampus)
– Make sure it says “Modified”!
– Register for FlipItPhysics and WebAssign
• Do both tonight!!!
• Note you can use their free trial offers (see syllabus)
– Textbook (see syllabus)
Common PHYS-218 Web-page
Grading
• Grading will be based on the following scales:
• I will curve all scores AFTER the final, but will
give you feedback along the way
– If your final score is higher than the lowest of the
midterms, that midterm be replaced by an average
score on that midterm and the final
FlipItPhysics
• Pre-lectures that you work on before the
lecture (for credit and required)
– Pass check-points and send feedback
Modified Mastering Physics
• Online homework management system
– Weekly assignments (for credit), somewhat elaborate grading
system with (harsh!) penalties for late submission
– Only access it via eCampus, do not use direct links for
registration! – you do not need a “course ID”
More on Lectures
• A follow up on the pre-lectures
– Focus on specific problems, typical mistakes and feedback from
your work on pre-lectures
– I assume you already know all basics and more and focus on
challenges, misconceptions etc.
• Clicker quizzes
– These are for credit, designed to check on your progress and
facilitate your learning
• Many “simpler” questions, but some will be pretty challenging
• A lot of focus on conceptual understanding plus
problems to illustrate the application of concepts
– Focus on “illustrative” problems in lecture, few hard problems
• Lectures give you the tools and teach you how to connect things,
the rest is you applying this knowledge as you train yourself in
solving problems using homework
Recitations
• Common implementation for all sections of this
course
• You typically have to do the homework before
the recitation
• At recitations, you will be working in groups of 34 learning to work out challenging problems
– Multiple concepts in a single problem
– Recitation instructor will facilitate your work, but will not be
solving the problem for you
– Each student will be turning in their own report, which will be
graded
• Additional short quizzes very possible
Labs
• Lab policies are uniform and set by the Department
– WebAssign is the online system used by the lab portion of the course
• Register today: http://webassign.net/tamu/login.html
– It will take you to TAMU SSO page to identify you, then will automatically place you in
the right class
What to Expect: PHYS-218
• Be prepared that this is one of very hard
and time consuming classes
– Need typically 12 hours of hard work a week
besides classes
• Inter-relation and intensity of the material
makes it harder:
– You miss one thing, but it will come and bite
you several times as the same concepts
repeat throughout the course
• If you can’t afford that much time, take this
class next semester
Independent Perspective
• From koofers.com
How To Do Well in PHYS-218
• Strategy:
– Maximize scores in all “service” categories
• Labs, recitations, HW, clicker quizzes
– Do your best on the exams
• Exams are the “make it or break it” part of the course
• Will “break it” if you don’t do well in “service” categories
• Final grade math’s “rules of thumb”:
– Low scores on HW will likely cost you a whole letter grade
• Most people have 90% and more on homework
– Low scores on labs or recitations will likely cost you a whole
letter grade
• Most people will have 80-90% for both
– 60% of those who frequently do not participate in clicker quizzes
and pre-lecture quizzes will lose a whole letter grade
• If you are in very high C range otherwise, you may still get a C; if you are in
the lower 60% of the C range, you will almost definitely get a D
How To Do Well in PHYS-218
• You won’t do well on exams unless you train
yourself in solving HW problems
– Do problems yourself: if someone explains you the
solution and you “understood” it, that’s not good
enough
– If you are stuck, ask for help with a similar problem; if
you had to get help with a HW problem, solve 5 more
similar ones from the book yourself
– Really helps to go beyond HW assignments and do
more problems from the book
– You will struggle withy many of the problems first, but
that’s the only way to get through. If you keep
pushing, you will notice that there will be a break
though point where things will start coming to you
easier
Clicker
• Model called “i>clicker 2”
– The original i>clicker will be okay as
well, but your other classes may
require i>clicker2
• Get them now before the bookstore
ran out of them!
– There seem to be some options to get
a discount when you purchase your
text book (see my web-page)
• Today use as a practice only, next
time we will use it for real
Registering Your clicker
•
•
•
•
1.Go to http://www.iclicker.com/support/registeryourclicker/
2.Enter your first and last names as they appear on your TAMU ID.
3.For "Student ID" enter your TAMU UIN.
4. For "Remote ID" enter the code that appears on the back of your
i>clicker2 (also on the LCD screen upon powering on your i>clicker2)
Clickers Setup
• Turn on your clicker (press the power
button)
• Set the frequency:
– Press and hold the power button
– Two letters will be flashing
– If it’s not “BD”, press “B” and then “D”
• If everything works, you should see
“Welcome” and “Ready”
Clicker Question 1
• Do you have your i>clicker with you today?
A) Yes
B) No
C) Maybe
D) I like pudding
We use the “BD” frequency in this class
Prepare for Monday
• Read material of Chapter 1 ASAP
• Do pre-lectures and check-points in
FlipItPhysics – check due dates (typically
Monday 8am)
– Provide feedback
• Lecture quizzes
– You will need your clicker up and running!
• Don’t forget the recitation and lab
meetings this week
– For many of you it is tomorrow and your
attendance is mandatory (will be checked)
MATH & SUCH
Converting Units
• Problem: express length of a football field in feet:
– 1 football field = 100 yards
– 1 yard = 3 feet
• Solution:
– 1 football field = 1 football field
– 1 football field = 1 football field x (1) x (1)
• Can always multiply by a unity; nothing should change
– 1 football field = 1 football field x (100 yards/1 football field) = 100 yards
• Got to yards above, which is already an improvement
– 1 football filed = 100 yards x (3 feet/yard) = 300 feet
• Got rid of yards and expressed in feet!
– Both are units of length!
• Another problem:
– Express speed v= 50 km/hour in m/sec
Problem Solving Overview
• There are good general problem solving
TRICKS
– Units checking
– Special case checking
– Etc.
• There are good METHODS of problem
solving that prepare you for the exams
We’ll use both to solve
problems in lecture
Problem Solving -1
What’s the first thing you should do
when you’re given a a problem?
• Draw a diagram!!!
– Usually good for some partial credit
• List givens and wants as variables
– Also a good bet for partial credit
Then use reasonable equations and
solve with variables
Problem Solving -2
• The speed of your car isn’t measured in
seconds, its measured in meters/second (or
miles/hour etc.)
• Paying attention to the units will help you
catch LOTS of mistakes on exams, quizzes
and homework!!
– If we ask what the mass of your car is,
make sure your answer is in kg (or lbs
etc.)
Every time you finish a problem ALWAYS
check the units of your answer!!
Problem Solving - 3
Check Reasonableness:
• Can you find another way to do the
same problem that gives the same
answer?
• Trivial choices of values for variables
give expected numerical answers?
Example: Zero, or infinity
Moving toward an Example
Problem
• Next we’ll do an example problem like one
of the homework problems in the text book
• Solve this problem using the right method
– Draw a diagram
– Convert the numbers to variables
– Solve to get a formula
– Plug in the numbers at the end
– Check
Example Problem
You want to measure
the height of a building.
You stand 2m away
from a 3m pole and see
that it’s “in line” with the
top of the building. You
measure 16 m from the
pole to the building.
16 m
What is the height of
the building?
Vectors
Vectors:
–Why we care about them
–Addition & Subtraction
–Unit Vectors
–Multiplication
Why do we care about Vectors?
• As you may have noticed, the world is not onedimensional
• Three dimensions: X, Y and Z. Example:
1. Up from us
2. Straight in front of us
3. To the side from us
– All at 90 degrees from each other. Three
dimensional axis.
• Need a way of saying how much in each
direction
For this we use VECTORS
Vector and Scalar
• Vectors have a magnitude AND a
direction
– 10 miles in the south direction
• Scalars are just a number
– Mass of your car
– Earth radius
Where am I?
•
•
•
•
Let’s say I’m here
You’re here (origin)
I call you on the cell phone.
How do I tell you how to
get to me?
• 2 equivalent ways:
•
•
Travel 11.2 km at an
angle of 26.5 degrees
Travel 10 km East then
5 km North
A single vector in arbitrary
direction can be thought of as
two vectors in nice simple
directions (like X and Y). This
can make things much easier
Vector Addition
• To specify where I am,
often doing the two vector
version is easier
Represent Graphically:
• Lay down first vector
• Lay down second vector
– Put the tail at the head
of the first vector
• The “Sum” is where I am
Re-write my location
• Describe my location
in terms of the sum of
two vectors



R  RX  RY
R
|R X |  |R| cos Θ
Ry
|RY|  |R| sin Θ
• Careful when using the
sin and cos
Rx
Specifying a Vector
• Two equivalent ways:
– Components Vx and Vy
– Magnitude V and angle q
• Switch back and forth
– Magnitude of V
|V| = (vx2 + vy2)½
• Pythagorean Theorem
– tanq = vy /vx
• Either method is fine, pick
one that is easiest for you,
but be able to use both
Things Due This Week
• Homework (via masteringphysics.com)
– Chapter 1: Math and stuff – due Sunday (3 days from now!)
• FlipItPhysics pre-lectures & check-points:
– Math and related topics – due Friday (2 days from now)
– Chapter 1 – due Sunday
• Monday lecture:
– Finish up Math & stuff, move to Chapter 2
• Before Monday start working on:
– Prepare for recitation on Chapter 1
– Homework problems for Ch. 2
– Pre-lectures for Chapter 2 due Wednesday 8AM!
• Wednesday lecture:
– Chapter 2 quizzes
• Lab (WebAssign!):
Prepare for the lab, complete all read pre-lab parts before the lab!