PHYSCI

• How the Greeks knew the Earth is spherical


  • Every object on Earth is compressed and converged toward the center forming a sphere
  • The North Star was believed to be at a fixed position in the sky, but when the Greeks traveled to places nearer the equator, they noticed that the North Star is closer to the horizon
  • During a lunar eclipse, the shape of Earth's shadow reflected on the Moon's surface is circular

  
• Eratosthenes' method to estimate the Earth's circumference


  Observed the shadow casts by a pillar and correlated it with the information that while an object in Alexandria during noontime cast a shadow, in Seyene the light rays that hit the water well is reflected back thus, no shadow is formed

  
• Astronomical phenomena known to man even before the invention of the telescope


  • Different phases of the moon
  • Lunar eclipse
  • Solar eclipses
  • The motion of stars "wanderers" the discovery of planets Mercury, Venus, Mars, Jupiter, and Saturn

  
• Tychonic model


  Earth is fixed and the Sun revolves around it, but the rest of the planets revolve around the Sun

  
• Kepler's laws of planetary motion


  • Law of Ellipse
  • Laws of Equal Areas
  • Law of Period

  
• The Geocentric Model dominated for thousands of years
• Kepler discovered the importance of Brahe's data in explaining the elliptical path of the planets and moon, varying speed of planets motion and the harmony of the distance of the planet and its motion

  
• Motion


  An object is in motion when it changes position with respect to a reference point

  
• Velocity


  Consists of an object's speed and direction

  
• Acceleration


  A change in an object's velocity
• Objects in a vacuum fall with uniform acceleration regardless of mass
• Force is not necessary to sustain horizontal motion
• Newton's First Law of Motion


  An object at rest remains at rest and an object in motion remains in motion in a straight line with a constant velocity unless an external force acts on it

  
• Law of Universal Gravitation


  Every object in the universe attracts every other object with a force directed along the line of centers for the two objects that is proportional to the product of their masses and inversely proportional to the square of the separation between the two objects
• Newton's Laws of Motion

  • First Law (Law of Inertia)
  • Second Law (Law of Acceleration)
  • Third Law (Law of Action - Reaction)
• Law of Conservation of Energy


  Energy is neither created nor destroyed, but it can only be transformed from one form to another
• Conservation of Linear Momentum


  The total momentum of the of the bodies isolated from the rest of the universe remains constant regardless of what happens within the system
• Laws of Thermodynamics


  • Zeroeth Law
  • First Law
  • Second Law
  • Third Law
• Coulomb's Law


  The force between two point charges is directly proportional to the magnitude of each charge and inversely proportional to the square of the distance between them
• Gauss's Law


  The net flow of an electric field through a closed surface is proportional to the enclosed electric charge
• Greeks who knew that the earth is round

  • Aristotle, Alexander the great, Seleucus of Seleucia, Eratosthenes, Claudius Ptolemy