Fisica%201%20per%20Biotecnologie%20Introduzione

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Fisica 1 per BiotecnologieIntroduzione
Lun h 1030Mer h 1030 Gio h 1030
Alessandro De Angelis E-mail deangelis_at_fisica.uni
ud.itRicevo il mercoledì, 830-930
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MAGIC
Telescopio Nazionale Galileo
La Palma, IAC 28 North, 18 West
Grantecan
MAGIC
MAGIC and its Control House
MAGIC
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www.fisica.uniud.it/deangeli/biotec

• Obiettivi Scopo del corso è di fornire gli
  elementi di base della fisica generale.
• Struttura Il corso si svolge nel I periodo del I
  anno, con 22 lezioni distribuite in tre unità di
  90 minuti ogni settimana. Nella pagina Web del
  corso e' pubblicata una versione aggiornata della
  struttura dettagliata delle lezioni (vedi tabella
  a pie' di pagina).
• Programma Unità di misura. Cinematica. Forze in
  natura gravitazione, elettromagnetismo.
  Dinamica. Energia. Oscillazioni cenni sul moto
  ondulatorio e sulle onde elettromagnetiche. 
• Testo Serway e Jewett - Principi di Fisica vol.
  1, ultima edizione, EdiSES appunti di lezione
  (che non sostituiscono il testo). Gli appunti di
  lezione e una selezione dei compiti degli anni
  precedenti sono reperibili nel sito del materiale
  didattico.

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www.fisica.uniud.it/deangeli/biotec

• Titolare Il titolare del corso si chiama
  Alessandro De Angelis. Riceve nell'orario
  riportato su SINDY, o su appuntamento scrivendo a
  deangelis_at_fisica.uniud.it. Melisa Rossi
  contribuisce al corso.
• Valutazione Nella sessione d'esame (due appelli)
  che segue il corso il voto proposto e' dato dal
  voto di un accertamento finale (valutato fino a
  30 punti) cui viene aggiunto un bonus da 0 a 6
  punti basato sulla valutazione dei compiti per
  casa. Lo studente che abbia superato la prova
  riportando un voto complessivo non inferiore a
  18/30 supera l'esame. Nelle sessioni successive
  (un appello a Luglio e uno a Settembre) l'esame
  consta di una prova scritta che include domande
  di teoria, o di un orale che include esercizi.
• Consigli
• Procurarsi il libro di testo ben prima
  dell'inizio del corso, magari sfogliarlo quando
  non si sa che fare...
• Dare un'occhiata agli argomenti della lezione
  successiva (il programma lezione per lezione e'
  dettagliato nella pagina Web del corso)
• Studiare regolarmente ogni giorno quanto svolto
  in classe e svolgere gli esercizi relativi.

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About Physics

• Provides a quantitative understanding of
  phenomena occurring in our universe
• Based on experimental observations and
  mathematical analysis
• Used to develop theories that explain the
  phenomena being studied and that relate to other
  established theories

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What is Physics? Model Building

• A model is a simplified substitution for the real
  problem that allows us to solve the problem in a
  relatively simple way
• Make predictions about the behavior of the system
• The predictions will be based on interactions
  among the components and/or
• Based on the interactions between the components
  and the environment
• As long as the predictions of the model agree
  with the actual behavior of the real system, the
  model is valid

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Particle Model

• The particle model allows the replacement of an
  extended object with a particle which has mass,
  but zero size
• Two conditions for using the particle model are
• The size of the actual object is of no
  consequence in the analysis of its motion
• Any internal processes occurring in the object
  are of no consequence in the analysis of its
  motion

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Theory and Experiments

• Should complement each other
• When a discrepancy occurs, theory may be modified
• Theory may apply to limited conditions
• Example Newtonian Mechanics is confined to
  objects traveling slowly with respect to the
  speed of light
• Used to try to develop a more general theory

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Standards of Quantities

• SI Système International
• The system used in this course
• Consists of a system of definitions and standards
  to describe fundamental physical quantities

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Time second, s

• Historically defined as 1/86400 of a solar day
• Now defined in terms of the oscillation of
  radiation from a cesium atom
• Some approximate time intervals, in s
• Age of the Universe 5 1017
• Since the fall of Roman Empire 5 1012
• Your age 6 108
• One year p 107
• One lecture 5 103
• Time between two heartbeats 1

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Length meter, m

• The human-scale definition 1/10000000 of the
  distance between the North Pole and the equator,
• through Paris
• Length is now defined as the distance traveled by
  light in a vacuum during a given time (1/3 10-8
  s)
• See table 1.1 for some examples of lengths

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Mass kilogram, kg

• The mass of a specific cylinder kept somewhere in
  Paris
• See table 1.2 for masses of various objects

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Number Notation

• Separation between units and decimals dot (.)
• When writing out numbers with many digits,
  spacing in groups of three will be used
• No commas, no dots
• Examples
• 25 100
• 5.123 456 789 12

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Reasonableness of Results

• When solving problem, you need to check your
  answer to see if it seems reasonable
• How many molecules in a liter of milk?
• Reviewing the tables of approximate values for
  length, mass, and time will help you test for
  reasonableness

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Systems of Measurements, SI Summary

• SI System
• Almost universally used in science and industry
• Length is measured in meters (m)
• Time is measured in seconds (s)
• Mass is measured in kilograms (kg)

ITS A LAW
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Prefixes

• Prefixes correspond to powers of 10
• Each prefix has a specific name
• Each prefix has a specific abbreviation
• The prefixes can be used with any base units
• They are multipliers of the base unit
• Examples
• 1 mm 10-3 m
• 1 mg 10-3 g

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Fundamental Derived Quantities

• In mechanics, three fundamental quantities are
  used
• Length
• Mass
• Time
• Will also use derived quantities
• These are other quantities that can be expressed
  as a mathematical combination of fundamental
  quantities
• Density is an example of a derived quantity It
  is defined as mass per unit volume
• Units are kg/m3

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Dimensional Analysis

• Technique to check the correctness of an equation
  or to assist in deriving an equation. Dimension
  has a specific meaning it denotes the physical
  nature of a quantity
• Dimensions (length, mass, time, combinations) can
  be treated as algebraic quantities
• Add, subtract, multiply, divide
• Both sides of equation must have the same
  dimensions
• Dimensions are denoted with square brackets
• Length L
• Mass M
• Time T
• Cannot give numerical factors this is its
  limitation

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Dimensional Analysis, example

• Given the equation x 1/2 a t2
• Check dimensions on each side
• The T2s cancel, leaving L for the dimensions of
  each side
• The equation is dimensionally correct
• There are no dimensions for the constant

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Conversion of Units

• When units are not consistent, you may need to
  convert to appropriate ones
• Units can be treated like algebraic quantities
  that can cancel each other out
• Always include units for every quantity, you can
  carry the units through the entire calculation
• Multiply original value by a ratio equal to one
• The ratio is called a conversion factor
• Example

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Order of Magnitude

• Approximation based on a number of assumptions
• May need to modify assumptions if more precise
  results are needed
• Order of magnitude is the power of 10 that
  applies
• In order of magnitude calculations, the results
  are reliable to within about a factor of 10

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Uncertainty in Measurements

• There is uncertainty in every measurement, this
  uncertainty carries over through the calculations
• Need a technique to account for this uncertainty
• We will use rules for significant figures to
  approximate the uncertainty in results of
  calculations

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Significant Figures

• A significant figure is one that is reliably
  known
• Zeros may or may not be significant
• Those used to position the decimal point are not
  significant
• To remove ambiguity, use scientific notation
• In a measurement, the significant figures include
  the first estimated digit
• 0.0075 m has 2 significant figures
• The leading zeroes are placeholders only
• Can write in scientific notation to show more
  clearly 7.5 x 10-3 m for 2 significant figures
• 10.0 m has 3 significant figures
• The decimal point gives information about the
  reliability of the measurement
• 1500 m is ambiguous
• Use 1.5 x 103 m for 2 significant figures
• Use 1.50 x 103 m for 3 significant figures
• Use 1.500 x 103 m for 4 significant figures

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Operations with Significant Figures

• When multiplying or dividing, the number of
  significant figures in the final answer is the
  same as the number of significant figures in the
  quantity having the lowest number of significant
  figures.
• Example 25.57 m x 2.45 m 62.6 m2
• The 2.45 m limits your result to 3 significant
  figures
• When adding or subtracting, the number of decimal
  places in the result should equal the smallest
  number of decimal places in any term in the sum.
• Example 135 cm 3.25 cm 138 cm
• The 135 cm limits your answer to the units
  decimal value

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Rounding

• Last retained digit is increased by 1 if the last
  digit dropped is 5 or above
• Last retained digit is remains as it is if the
  last digit dropped is less than 5
• Saving rounding until the final result will help
  eliminate accumulation of errors

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Coordinate Systems

• Used to describe the position of a point in space
• Coordinate system consists of
• A fixed reference point called the origin
• Specific axes with scales and labels
• Instructions on how to label a point relative to
  the origin and the axes

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Cartesian Coordinate System

• Also called rectangular coordinate system
• x- and y- axes intersect at the origin
• Points are labeled (x,y)
• 3 coordinates (x,y,z) are enough to define the
  position of a particle in space

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Polar Coordinate System

• Origin and reference line are noted
• Point is distance r from the origin in the
  direction of angle ?, ccw from reference line
• Points are labeled (r,?)

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Polar to Cartesian Coordinates

• Based on forming a right triangle from r and q
• x r cos q
• y r sin q

Cartesian to Polar

• r is the hypotenuse and q an angle