Transcript In Physics - Millersville University

Welcome to Physics-131
Physics-I
TARIQ H. GILANI
ASSOCIATE PROFESSOR
MILLERSVILLE UNIV.
ASSISTANT PROF (2002).
PENN STATE UNIVERSITY
STATE COLLEGE, PA (2000) ----- POST DOC.
JOHN CARROLL UNIVERSITY
CLEVELAND, OH (2001) ----- VISITING ASS. PROF.
PhD ---- KYOTO UNIVERSITY, JAPAN (1997).
Office: R 236 (STB)
Ph. 872-3291
E-mail: [email protected]
Welcome to
Physics 131
Text: Physics, 9th Edition, Cutnell and Johnson
Lab Notebook: Bound Lab Notebook, quad ruled, (9.75” x 7.5”).
Please bring this lab notebook to your first meeting.
A scientific calculator for use in Lab.
Reference Books:
1. Physics, 2nd Edition, Urone.
2. Physics For Scientists and Engineers, 4th Edition, Serway.
3. University Physics, 10th Edition, Young & Freedman.
Purpose
It
is
an
introductory
algebra-based
course.
To become familiar with basic ideas of physics – Mechanics, Heat, Energy,
Waves and Sound. The primary focus will be on concepts
Class
Lectures
Discussion
Problems
Demonstrations
Each Lab must be satisfactorily completed to pass this course
Exams and Grading
There will be Four in-class exams during the semester (Each
Friday). In addition to the exams, laboratory and attendance
will be considered. Each of these counts towards your final
grade as follows:
In-class exams
Attendance
Labs:
80%
10%
10%
Tentative Dates
Every Friday
--------------------------
Each Lab must be satisfactorily completed to pass this course
Labs
You must complete all lab work.
Missed Work
If you miss a lab or exam for any reason, you
must contact your instructor as soon as
possible for arrangement.
My phone # 872-3291, e-mail:
[email protected]
Department office: 872-3411 (In case you have
difficulty in finding me)
90-100%
A
65-69.9%
C+
85-89.9%
A-
60-64.9%
C
80-84.9%
B+
55-59.9%
C-
75-79.9%
B
50-54.9%
D+
70-74.9%
B-
45-49.9%
D
<45%
F
The minimum score for any grade may be lowered based on the difficulty of quiz or
examination questions.
Syllabus and Other Information
www.millersville.edu/~tgilani
What is Phys 131?
Physics
Mechanics
Heat and
Energy
Waves and
Sound
What is Physics?
Physics --- Study of basic nature of matter and the interactions that govern
•
•
the behavior
Observing and understanding the Physical world ----- Physics is most basic of
all sciences.
It predicts “how nature will behave in particular situation on the basis of
experiments.
• Space Science
• Transportation Industry
• Electronics and Computer Science
•Medical Equipments
Physics tells us the rules of the
universe.
In Physics
• How to see the world?
• Use reasoning
• Apply the Physical Principles
To enjoy more!!
Measurements
Experiments involve the measurements of quantities
Measurements must be accurate, precise and reproducible
First step --- defining units
Research needs communication among international researchers
Common Language --- System of Units
How small an atom is?
SI
CGS
BE
System of measurements
SI is most widely used
Along with few more are base
Length, Mass and Time
Their units are basic units
All other units are derived
MKS
Meter (m)
Length
Mass
CGS
centimeter (cm)
Kilogram (Kg)
Second (s)
Time
BE
foot (ft)
gram (g)
Slug (Sl)
Second (s)
Second (s)
Metric Units
Length -------- meters (mm, cm, km,…)
Mass --------- Kilograms (mg, cg, g, …)
Time ---------- seconds (ns, ms, …)
1 Kg = 1000 g
1 g = 1000 mg
Main Advantage
Conversion within the system is quite easy
• English System
• Metric system
1999--- NASA’s Mars climate orbiter became a victim of confusion.
Cost US$125 million
SI System (International system):
Three basic units of measurements
Length or distance
Meter (m)
Mass
Kilogram (kg)
Time
Second (s)
SI System or
MKS system
Kilometer (km)
centimeter (cm)
Mega meter (Mm)
Giga meter (Gm)
millimeter (mm)
micrometer (m)
nanometer (nm)
Power of 10
Example:
To multiply
100,000 = 105 and 0.00001 = 10-5
102X106 =
1000 = 103
105X10-7 =
1Million = 106
1 Micro = 10-6 and so on
To divide
The universe is only seconds old
102/106 =
A Million Trillion seconds
105/10-7 =
106X1012 = 1018s
Commonly used Metric Prefixes
Prefix
giga
mega
kilo
centi
milli
micro
nano
Figure
=
=
=
=
=
=
=
1000,000,000
1000,000
1000
1/100
1/1000
1/1000,000
1/1000,000,000
Scientific
Notation
=
109
=
106
=
103
= 0.01 = 10-2
= 0.001 = 10-3
=
10-6
=
10-9
Words
=
=
=
=
=
=
=
1 billion
1 million
1 thousand
1 hundredth
1 thousandth
1 millionth
1 billionth
Can you tell with out using calculator?
• How many inches are there in 6 miles?
• How many meters are there in 6 km?
How small an atom is?
Pretty small
1 Million (106) atoms if put
together can not be bigger
than this period at the end of
this sentence.
•1970 --- First direct evidence of atom using SEM
•1983 --- First 3-D image of an atom was obtained using STM
Atoms were dragged and arranged to write the name of laboratory (IBM).
Whatever system of units you use --- be consistent
Can not mix ---- length in ft and mass in kg
A quantity is always expressed by a number and its units (if it has)
Distance --- units of length
Dimensions
Speed in units of length divided by units of time
Dimension of Length
Dimension of speed =
Dimension of Time
S=
L
T
Dimension Analysis
First check of mathematical relation
Mathematical relation must have same dimensions on both side of the equation
Example
X is distance
X=½vt
Dimensions
2
LHS
v is speed
L
T
L
=LT
Relation is wrong
X=½vt
t is time
RHS
has the right dimensions
T
2
Trigonometry

h
Sin   o
h
Cos 
Adjacent ha
ha
h
Tan 
ho
ha
h2 = ho2 + ha2
opposite ho
Basic Relations
Scalars and Vectors
Scalar --- Quantity that need magnitude only
Mass, Volume, Temperature
Vector --- Quantity that need magnitude and direction
Force, displacement
Arrow --- direction
Length --- magnitude
2 Km due East
4 Km due East
Vector is represented by Boldface letter or Arrow on the symbol
A or A
A scalar is represented by italic symbol
A vector has magnitude and direction
A = 2 m due west
Magnitude = 2 m
A
Vector Addition
Magnitude and direction
• When all vectors are in the same direction
A = 2 m due East and B = 5 m due East
Their resultant R = A + B = 7 m due East
• When two vectors are pointing opposite
A = 2 m East
B = 5 m West
=> R = 3 m West
• Perpendicular vectors
A = 2 m East
B = 5 m North
West
North
R
B

East
A
R = [A2 + B2]1/2
Direction
B
A
  Tan 1 ( )
Degrees North of East
South
Graphical Method
• Draw Vector A
Must use same scale
• Draw vector B starting at the arrow of A
• R (= A + B) is from tail of A to head of B
• Measure the Length and angle of R
Subtraction
A–B
= A + (- B)
Multiplying a vector with -1
=> magnitude remains the same while direction is reversed
A = 2m East
-A = 2m west
Vector Components
x-component
Along x-axis
y-component
Along y-axis
A = 2 Km at 30 o North of East
Ax = A
cos 
Ay = A Sin 
Along x-axis
Along y-axis
y-axis
A
Ax
Ay
X-axis
Adding by Vector components
A = 2 Km 30o North of East
B = 3 Km 60o North of East
Ax = 2 Cos (30o)
Bx = 3 Cos (60o)
Ay = 2 Sin (30o)
By = 3 Sin (60o)
Rx = Ax + Bx
Ry = Ay + By
R = [R2x + R2y ]1/2
  Tan (
1
Ry
Rx
)
Summary
• Units ---- SI System (length  m, Mass  Kg and Time s).
• Dimensions --- First check of Mathematical relation.
• Trigonometry --- Cosine, Sine and Tangent functions.
• Scalar and Vector Quantities.
• Scalar can be described completely by magnitude
• Vector needs direction along with magnitude to be fully
described.
• Vector Addition and Subtraction
• Graphical Method
• Vector Components Method
Practice
• Are two vectors with the same magnitude necessarily be
equal?
• Conceptual Questions (FOC): 8, 15, 17
• Problem 6, 15, 37, 40, 46 and 49