The document summarizes key concepts and developments in the history of physics. It outlines important contributions from thinkers like Aristotle, Copernicus, Kepler, Descartes, Galileo, Snell, Fermat, Pascal, Huygens, Hooke, and others. Their work established foundations of motion, mechanics, astronomy, light and optics. Key advances included the first quantitative laws of motion, definitions of uniform and accelerated motion, average speed theorem, planetary laws, Cartesian coordinates, telescope, laws of refraction, least time principle, hydrostatics, elasticity, and gravitation. The document traces physics from ancient Greece to the 20th century, highlighting how early theories paved the way for modern understandings.

1. Concepts and Developments in
Physics 2
Jonis V C
Assistant Professor
Department of Physics
St. Xavier’s College for women, Aluva
9/19/2021 1

2. History of Physics…...
• Quantitative law of motion v = k. F/R by Aristotle (384-322B.C.)
velocity α F , 1/R where F force and R resistance.
• Alternative to Aristotle v = k(F - R) by Avempace
Minimum force F = R is required to initiate motion.
• Definition of uniform motion by Richard Swine,
(equal distances in equal intervals of time)
Definition of uniform acceleration by William Heytesbury (1300)
(changes velocity equally in equal intervals of time)
9/19/2021 Jonis V C, Assistant Professor, St. Xavier's College for women, Aluva 2

3. • Average speed theorem by Nicole de Oresme
(average speed over any interval of time for a uniformly accelerated motion
starting from rest is exactly half of final speed.)
• Another definition of motion, v = k log(F/R) in 1328 by Thomas Bradwardine
• The term impetus (I) to represent the impressed force of moving objects was
introduced by Jean Buridan which is the product of velocity and quantity of
matter.
• Difference between rectilinear and circular impetus by Marsillius
9/19/2021 Jonis V C, Assistant Professor, St.Xavier's College for women, Aluva 3

4. • Difference between kinematics and dynamics by William of Ockham (1300-1350)
kinematics definition and measurement of motion
dynamics measurements of force and their effects
• Heliocentric theory by Copernicus (1473-1531)
9/19/2021 Jonis V C, Assistant Professor, St. Xavier's College for women, Aluva 4

5. • Laws of planetary motion by Johannes Kepler(1571-1630)
1. All planets move around the sun in elliptical orbits in which sun is at one of it’s
foci.(1609)
9/19/2021 Jonis V C, Assistant Professor, St. Xavier's College for women, Aluva 5

6. 2. The line joining the sun and the planet sweeps out equal areas in equal intervals
of time.(1609)
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3. The square of the orbital periods of the planets are directly proportional to
the cube of semi major axis.(1618) T² α a³

8. Contd…..
• Cartesian coordinate system by Rene Dascartes
• First telescope in 1610 by Galileo Galilei and confirmed heliocentric theory,
performed tower of Pisa experiment…….
• Laws of refraction, radius of earth determination by Willebrord Snell
• The principle of least time for propagation of light rays in any medium by Fermat
(light travels in straight lines and take the path of least time)
9/19/2021 Jonis V C, Assistant Professor, St. Xavier's College for women, Aluva 8

9. Contd…….
• Theory of hydrostatics by Blaise Pascal (1623-1662).
• Laws of collision of bodies, parabolic mirrors in telescopes, standard
length of oscillation of pendulum clock by Christopher Wren (1632-
1723).
• Invention of mercury barometer, parabolic ballistics by Torricelli
(1608-1647).
• Theory of light waves by Christian Huygens (1629-1695).
• Hooke’s law of Elasticity (F = -k x) ,law of Gravitation by Robert Hooke
(1635-1703).
9/19/2021 Jonis V C, Assistant Professor, St. Xavier's College for women, Aluva 9

10. Last century….yet to explore…..
• Contributions to developments of 20th century comes from many eminent
scientists Einstein, Newton, J.J. Thomson, Marie and Pierre Curie, Rutherford,
Rayleigh….. and of course, Indian scientists…
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Jonis V C, Assistant Professor, St.Xavier's College for women,
Aluva
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