PS

• The Greeks are noted for their contribution in different fields. They were not only great philosophers but great scientists and mathematicians as well.
• Ptolemic Model


  It claims that the planets moved in a complicated system of circles.
• Oblate Spheroid


  The shape of the Earth.
• The North Star has a fixed position in the sky. However, when the Greeks traveled to places nearer the equator, like Egypt, they noticed that it is closer to the horizon.
• Aristotle


  A student of Plato and considered as one of the greatest philosophers of his time; his earth-centered view dominated for almost 2,000 years.
• Pythagoras first proposed the spherical earth.
• Anaxagoras explained the causes of the phases of the moon and the shadow Earth cast on the moon during a lunar eclipse was circular.
• How did the ancient Greeks come up with the measurement of the spherical Earth?

  By getting the CIRCUMFERENCE
• Aristotle's supporting arguments

  • Position of the North Star
  • The shape of the moon and the Sun
  • Ships disappearing over the horizon
• Eratosthenes measured the Earth's circumference with a stick, a knowledge of the distance from Alexandria to Syene and geometry, and calculated the circumference of the Earth to be approximately 40,000 kilometers.
• Hiparrchus made a compilation of 850 stars and developed a method for predicting lunar eclipses.
• Aristarchus proposed that the Sun was the center of the Universe (Heliocentric).
• Claudius Ptolemy proposed the geocentric model- Earth is the center.
• Gnomon


  Used in systematically observing the motion of the sun.
• Phases of the Moon

  • New Moon
  • Waxing Crescent
  • First Quarter
  • Waxing Gibbous
  • Full Moon
  • Waning Gibbous
  • Last Quarter
  • Waning Crescent
• Lunar Eclipse

  • Earth is the center
  • Happens during a Full moon
  • Occurs about twice every (1) year
  • Lasts for about an hour
• Solar Eclipse

  • Moon is the center
  • Happens during a New moon
  • Occurs about twice every three (3) years
  • Lasts for a few minutes
• Penumbra


  The light shadow
• Umbra


  The dark shadow
• Diurnal Motion


  The daily motion of the sun, moon, stars, and planets that appear to move across the sky
• Annual Motion


  The apparent yearly movement of stars as observed from Earth as a direct effect of the Earth's revolution around the sun
• Precession of the Equinoxes


  The observable phenomena of the rotation of the heavens which spans a period of 25, 920 years
• Tycho Brahe made accurate observations of the movement of celestial bodies.
• Johannes Kepler formulated the Laws of Planetary motion.
• Kepler's Laws of Planetary Motion

  • 1st Law (Law of Ellipses) – planets follow an oval or an ellipse orbit
  • 2nd Law (Law of Equal Access) – the imaginary line drawn from the center of the Sun to the center of the planet sweeps out an equal area of space in equal time intervals
  • 3rd Law (Law of Harmonies) – the square of a planet's orbital period is proportional to the cube of a planet's average distance from the sun
• Motion


  The action of changing location or position
• Types of Motion

  • Horizontal and vertical motion
  • Projectile motions
• Rate of Fall/Acceleration


  Can be used to derive horizontal, vertical, and projectile motions
• Aristotelian Concept of Motion

  • Natural Motion - objects move and return to its natural state based on its material or composition
  • Violent Motion - objects require push or pull to maintain horizontal motion
• Galileo Galilei is considered as the "Father of Modern Physics".
• In the absence of resistance, objects would not fall depending on their weight, but in the time of fall.
• Galileo used the inclined ramp to measure the acceleration of an object.
• First Law of Motion (Inertia)


  • Object at rest stays at rest and object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force
  • Mass is proportional to its inertia
• Types of Inertia

  • Inertia of Rest - an object will stay in place unless something moves it
  • Inertia of Motion - an object will continue at the same speed until a force acts on it
  • Inertia of Direction - an object will stay moving in the same direction unless a force acts on it
• Force


  A push or pull, measured in Newtons (N)
• Friction


  A force that opposes motion between any surfaces that are touching
• Net Force


  The total combination of forces acting on an object
• Rene Descartes was the first who studied and explained the concept of refraction.
• Rene Descartes explained the emergence of colors of light through the concept of the plenum, the invisible substance that permeated the universe.
• Isaac Newton studied the emergence of colors of light through a prism and stated that the difference in refraction was due to the differences in the mass of the colors of light.