Galileo on Motion
Galileo on Motion
“My purpose is to set forth a very new science dealing with a very ancient subject. There is, in nature, perhaps nothing older than motion, concerning which the books written by philosophers are neither few nor small; nevertheless I have discovered by EXPERIMENT some properties of it which are worth knowing and which have not hitherto been either observed or demonstrated.”
~ Galileo
“My purpose is to set forth a very new science dealing with a very ancient subject. There is, in nature, perhaps nothing older than motion, concerning which the books written by philosophers are neither few nor small; nevertheless I have discovered by EXPERIMENT some properties of it which are worth knowing and which have not hitherto been either observed or demonstrated.”
~ Galileo
Scientific revolution
Supporter of Copernicanism
Telescope
First and second laws of
motion
Experiment
Scientific method
“Father of modern
Astronomy”
“Father of modern physics”
“Father of science”
Freedom of thought & the
Catholic Church
LegacyLegacy
So, who’s Galileo?
Bridging the Gap: Aristotle to Galileo
Bridging the Gap: Aristotle to Galileo
Philoponus 533 A.D.
Avicenna 980 A.D.
Oresme 1330’s
Buridan
Ockham 1300’s
Born in 1564 in Pisa of Vincenzo Galilei and Guilia Ammannati Florence University of Pisa; 1581-1585 Chair of Mathematics Univ. of Pisa 1589 Father dies in 1591; Professory of Mathematics at the University
of Padua Meets Maria Gamba; Virginia (later Sister Maria Celeste) is born
(1600), Livia (1601), later Sister Arcangela, and Vincenzio (1606) 1609; the spyglass Cardinal Robert Bellarmine 1616 wrote the Letter to the Grand Duchess 1630 wrote Dialogue Concerning the Two Chief Systems of the
World Inquisition bans the Dialogue and Galileo is sentenced to lifetime
house arrest 1634 his daughter, Virginia, dies Disourses are smuggled out Died 1642
Born in 1564 in Pisa of Vincenzo Galilei and Guilia Ammannati Florence University of Pisa; 1581-1585 Chair of Mathematics Univ. of Pisa 1589 Father dies in 1591; Professory of Mathematics at the University
of Padua Meets Maria Gamba; Virginia (later Sister Maria Celeste) is born
(1600), Livia (1601), later Sister Arcangela, and Vincenzio (1606) 1609; the spyglass Cardinal Robert Bellarmine 1616 wrote the Letter to the Grand Duchess 1630 wrote Dialogue Concerning the Two Chief Systems of the
World Inquisition bans the Dialogue and Galileo is sentenced to lifetime
house arrest 1634 his daughter, Virginia, dies Disourses are smuggled out Died 1642
Galileo’s LifeGalileo’s Life
“Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the characters in which it is written. It is written in the language of mathematics, and its characters are
triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it; without these one is wandering in
a dark labyrinth.”
Galileo – from The Assayer
“Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the characters in which it is written. It is written in the language of mathematics, and its characters are
triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it; without these one is wandering in
a dark labyrinth.”
Galileo – from The Assayer
WorksWorks
De Motu (1602-1604) never published
Dialogue Concerning the Two Chief Systems of the World (1625-1630) -1632
Discourses and mathematical demonstrations concerning the two new sciences (1633-1642)-1638
De Motu (1602-1604) never published
Dialogue Concerning the Two Chief Systems of the World (1625-1630) -1632
Discourses and mathematical demonstrations concerning the two new sciences (1633-1642)-1638
Galileo’s QualifiersGalileo’s Qualifiers
Rectilinear vs. Circular Motion Straight line motion or motion parallel
with the surface of the earth? Criterion of Simplicity Agreement with experiment
Rectilinear vs. Circular Motion Straight line motion or motion parallel
with the surface of the earth? Criterion of Simplicity Agreement with experiment
Kinematics: Quantitative description of the motion of bodies
VS.Dynamics: Causes of such motion
Kinematics: Quantitative description of the motion of bodies
VS.Dynamics: Causes of such motion
Naturally Accelerated Motion/Constant
Acceleration
Naturally Accelerated Motion/Constant
Acceleration Vs. uniform motion – motion in
which equal distances are covered in equal increments of time
“A motion is said to be uniformly accelerated when, starting from rest, its speed receives equal increments in equal times”
Vs. uniform motion – motion in which equal distances are covered in equal increments of time
“A motion is said to be uniformly accelerated when, starting from rest, its speed receives equal increments in equal times”
Inclined Plane Experiments
Inclined Plane Experiments
http://brunelleschi.imss.fi.it/genscheda.asp?appl=SIM&xsl=multimed&lingua=ENG&chiave=500045
http://brunelleschi.imss.fi.it/genscheda.asp?appl=SIM&xsl=multimed&lingua=ENG&chiave=500065
http://brunelleschi.imss.fi.it/genscheda.asp?appl=SIM&xsl=multimed&lingua=ENG&chiave=500045
http://brunelleschi.imss.fi.it/genscheda.asp?appl=SIM&xsl=multimed&lingua=ENG&chiave=500065
~ 100 trials with various inclinations for various lengths of time
What do we make of this?What do we make of this?
Finds that the distance of descent always varies closely to the square of the time
Algebra had yet to be applied to such problems
The final velocity of the ball depended on how high the plane was, not directly to the plane’s incline angle
Finds that the distance of descent always varies closely to the square of the time
Algebra had yet to be applied to such problems
The final velocity of the ball depended on how high the plane was, not directly to the plane’s incline angle
Projectile MotionProjectile Motion
1. Constant downward acceleration2. Maintains constant horizontal velocity
1. Constant downward acceleration2. Maintains constant horizontal velocity
• Treat vertical and horizontal motions independently
• Combination of two components will agree with observed trajectory
•Observed trajectory is parabolic
Projectile MotionProjectile Motion
Derived Equations
Horizontal x = vot
Vertical y = 1/2gt2
Parabolic y = ( g ) x2
Trajectory 2v2o
Derived Equations
Horizontal x = vot
Vertical y = 1/2gt2
Parabolic y = ( g ) x2
Trajectory 2v2o
Projectile MotionProjectile Motion
http://brunelleschi.imss.fi.it/genscheda.asp?appl=SIM&xsl=multimed&lingua=ENG&chiave=500098
The Components of MotionThe Components of Motion
http://www.makingthemodernworld.org.uk/larning_modules/maths/04.TU.02/?section=7http://www.makingthemodernworld.org.uk/larning_modules/maths/04.TU.02/?section=7
Inertia Inertia
Momentum – product of the weight of a body times its velocity
Inertia - a body in motion tends to stay in motion (doesn’t specify straight-line)
http://id.mind.net/~zona/mstm/physics/mechanics/forces/galileo/galileoInertia.html
Momentum – product of the weight of a body times its velocity
Inertia - a body in motion tends to stay in motion (doesn’t specify straight-line)
http://id.mind.net/~zona/mstm/physics/mechanics/forces/galileo/galileoInertia.html
http://brunelleschi.imss.fi.it/genscheda.asp?appl=SIM&xsl=multimed&lingua=ENG&chiave=500135
Break from Aristotelian Philosophy?
Break from Aristotelian Philosophy?
Objects are no longer “purposeful” – break from teleology
***Disclaimer: Concepts of inertia did not begin only with Galileo
Objects are no longer “purposeful” – break from teleology
***Disclaimer: Concepts of inertia did not begin only with Galileo
Galileo on AristotleGalileo on Aristotle
Pg 84 in book and open discussion Pg 84 in book and open discussion
PisaPisa
Dropped balls diff. mass
Independent of mass
Thus, disproving Aristotle
Dropped balls diff. mass
Independent of mass
Thus, disproving Aristotle
Questions?Questions?Summary: http://brunelleschi.imss.fi.it/genscheda.asp?
appl=SIM&xsl=multimed&lingua=ENG&chiave=500012Summary: http://brunelleschi.imss.fi.it/genscheda.asp?
appl=SIM&xsl=multimed&lingua=ENG&chiave=500012
All truths are easy to understand once they are discovered; the point is to discover them.
Galileo
All truths are easy to understand once they are discovered; the point is to discover them.
Galileo