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• The Earth's shape

  The Earth was round like a ball
• Evidence on the Earth's shape

  • When travelling northward, stars in the north get higher in the sky while stars in the south get lower. The reverse happens when travelling south
  • Looking at the moon during a lunar eclipse
• Celestial motion


  The motion of planets, the Moons and the stars
• Diurnal motion


  Daily rotation of the Earth, Moon, Stars and Sun
• Annual motion


  Revolution of the planet Earth around the Sun for a length of 365 days, and six hours
• Terrestrial motion


  The motion of everyday objects
• Plato's view of the cosmos


  • The earth was in the center of the universe and did not move
• Eudoxus' view of the cosmos


  • Planets and stars rotated around the Earth in circular motion
  • Observed that planets did not follow a uniform circular motion and proposed retrograde motion
• Aristotle's view of the cosmos


  • The Earth was the center of the universe
• Aristarchus' view of the cosmos


  • The first to introduce the sun-centered solar system
  • Interest on the size of the universe and the distance between the planets
• Ptolemy's view of the cosmos


  • Follower of Aristotle's idea and constructed an elaborate model based on Mathematics
  • The Ptolemaic model, which is geocentric system places the Earth at the center of the universe
• Copernicus' view of the cosmos


  • Gave credit to the first modern heliocentric system
  • Set the correct order of the planets based on the extent of their retrograde motion
• Tycho Brahe's contributions


  • Accurate measurements of the stars and planets for over 20 years
  • Developed a quadrant that was used to measure the position of the stars with precision
• Kepler's contributions


  • A believer of Copernican's heliocentric universe
  • Became a major figure in the scientific revolution in the 17th century because of his planetary motion that formed the basis for Newton's theory of universal gravitation
• Galileo's contributions


  • Used his first telescope in 1609 to study the moon, the stars and the sun
  • These discoveries cast doubts on Ptolemaic geocentric theory that heaven is perfection
• Motion


  The movement or change in location of an object
• Aristotelian concept of motion


  • Terrestrial motion - Limited and vertical motion
  • Celestial motion - Circular and endless motion
  • Projectile motion - The motion of a stone after it leaves the hand of a thrower. Composed of both natural motion and imposed motion. Aristotle believed that everything moved must be moved by something
• Galilean concept of motion


  • Natural motion - not constrained by an external force
  • Non-natural motion - also called Impressed motion, occurs when an object is pushed into some non-natural motion by an external force; projectile motion is the key
• Acceleration


  An object that is slowing down, speeding up or changing direction is said to be accelerating
• Galileo's concept of acceleration and horizontal motion

  • Lighter object moved slightly ahead of the heavier object during initial stage of free fall but heavier object caught up and eventually passed lighter object
• Motion with constant velocity

  When object travels the same distance every second, then the object is moving with constant velocity. The magnitude of velocity and direction of velocity both remain constant
• Speed


  How fast an object moves. This is constant and does not indicate direction of motion
• Velocity


  Combination of speed and direction, defined as the rate of change of position
• Units of velocity


  meters per second (m/s), kilometers per hour (km/h or kph) and miles per hour (mi/h or mph)
• Constant velocity


  A vector
• Newton's first law of motion (law of inertia)


  • State of Rest: If body is at rest, it remains at rest until some external forces act on it
  • State of Motion: If a body is in motion, it continues to move with the same speed in the same direction until an external force acts on it and changes its velocity
• Newton's second law of motion (law of force)


  • Acceleration of a body is inversely proportional to its mass, directly proportional to the force and in the same direction as the force
• Newton's third law of motion (law of reactions)


  • For every action, there is an equal and opposite reaction
• Visible light


  The light that humans can see even animals and insects
• Light


  Scientists often call light electromagnetic radiation
• Properties of light

  • Light travels in a straight line and fast in a vacuum while slow down when it passes to an solid object
• Particle theory of light


  • The particle theory suggests that light particles always travel in a straight line
• Wave theory of light


  • The wave theory of light suggests that the beam of light spreads and becomes wider as light passes through a narrow slit
• Reflection


  Bouncing of lights when it hits an object. If the surface is perfectly smooth, light rays undergo reflection
• Refraction


  The change in direction of light wave as light passes from one transparent medium to another such as in glass or water
• Transmission


  Some materials allow much of the light that falls on them to pass through the material without being reflected. Materials such as glass allow transmission of light through them are called transparent
• Absorption


  This occurs when an object does not reflect or transmit the light instead it is taking in. Ability of objects to absorb light is dependent on the electromagnetic frequency of the light being transmitted and the nature of the atoms in an object