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

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Title: Fisica%201%20per%20Biotecnologie%20Introduzione

1
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
2
MAGIC
Telescopio Nazionale Galileo
La Palma, IAC 28 North, 18 West
Grantecan
MAGIC
MAGIC and its Control House
MAGIC
3
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.

4
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.

5
()
6
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

7
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

8
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

9
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

10
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

11
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

12
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

13
Mass kilogram, kg

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

14
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

15
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

16
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
17
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

18
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

19
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

20
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

21
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

22
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

23
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

24
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

25
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

26
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

27
Coordinate Systems