Little Shop of Knowledge

What is Mechanics?

 

The chapter introduces two different notions of what mechanics is. The first one is a practical definition that describes it as “that area of knowledge concerned with the construction, design, and operation of machines.” While the second one is a much more abstract and theoretical definition, describing mechanics as “that area of knowledge that treats of motions and tendencies to motions in material bodies.”

 

Key Questions

 

This book has a particular approach to physics which includes much of the philosophy and the authors involved in this conversation, which is why some concepts may not be clear and formulaic as in other types of textbooks but rather questions are instilled in the beginning to start pondering on whether we actually know what such concepts are. “It’s important to realize that few if any of these notions come to us as givens; rather they had to be created, improved and perfected, which processes may take years if not centuries and possibly minds of surpassing brilliance.

 

Some of these questions are:

What is Motion?

What is Distance?

What is Time?

What is Speed?

What is Acceleration?

 

Aristotle

 

Probably the most acclaimed and criticized physics of previous times. Whether he’s right today or not, his ideas were seen as a precise representation of reality for almost 2,000 years. (He lived from 384-322 BCE and harsh criticism of what he proposed began around 1600CE).

 

He published two major treatises on the physical world: Physics and On the Heavens. Where he expresses a stand that seemed to linger between the two main systems of thought at the time; The Atomistic and Platonic ones. 

 

Chapter 2: Galileo and Terrestrial Mechanics

 

Chronology of Galileo’s Life

 

1564: Born in Pisa, Feb. 15.

1575: Studies at monastery of Santa Maria, Vallombrosa. Becomes novice in the Vallombrosan order.

1581: Enrolls in University of Pisa for medical studies but turns to mathematics.

1583-1588: Discovers the isochronism of the pendulum and that the time of swing of a particular length is independent of the amplitude of the swing. Isochronous: if the events occur regularly, or at equal time intervals.

1589: Has composed treatise on the center of gravity in bodies and invented a hydrostatic balance: Becomes mathematics professor ar Pisa.

1592: Becomes professor of mathematics at the University of Padua

1597: Tells Kepler through a letter that he had accepted Copernicanism few years earlier.

1609: Makes his own telescope (Using device constructed by Hans Lipperhey) and uses it for astronomical observation.

1610: Publishes Sidereus Nuncius (Starry Messenger) where he announces his discovery of the mountainous surface of the moon, 4 moons of Jupiter, and vast number of stars seen through the telescope. Resigns from Padua University; moves o Florence with Grand Duke Cosimo II de Medici as patron.

1613: Publishes Letters on Sunspots. (By this time Copernicanism isbeginning to cause controversy).

1615:Cardinal Robert Bellarmine urges Galileo to present Copernicanism only in a hypothetical manner.

1616: Holy Office bans Copernicus’s book; Galileo is warned not to defend Copernicanism.

1620:Congregation of the Index says that, if observed, alow reading of Copernicus’s book.

1621: Pope Paul V, Cardinal Bellarmine, Cosimo de Medici die.

1624: Travels to Rome and convinces Pope to let him write on the Copernican system. (As long as it was treated hypothetically).

1632: Publishes Dialogo… Sopra I due massimi sistemi del mondo: Tolemaico, e Copernicano. (Dialogue Concerning the Two Chief world systems –Ptolemaic and Copernican). Vigorously advocating Copernican System.

1633: Trial of Galileo in which his Dialogue is Banned. Galileo  avoids Copernican System.

1638: Publishes his Discorsi e dimostrazioni matematiche intorno a due nuove scienze: which is the beginning of modern mechanics.

1642: Galileo dies on January 8.

 

Questions:

• How do bodies move on the Earth?

• Did Galileo have a notion of inertia and did he discover the law of internia?

• What was the relation between Galileo’s mechanics and the Copernican system?

• What role did experiment play in Galileo’s methodology?

• To what extent was Galileo’s thought indebted to the ideas of his predecessors?

• What overall philosophical position did he espouse?

• In general, how significant was his contribution to mechanics?

 

Does a Falling Body’s Weight Influence Its Rate of Fall?

 

Aristotle: Claims that bodies fall at rates related to their weight.

 

Galileo, Two New Sciences

 

Simplicio, Salviati, Sagredo discuss the question above.