Physical Science 1

• Diurnal motion


  Apparent daily motion of stars and other celestial bodies across the sky due to Earth's rotation

  
• Planetes


  Wandering stars (planets)
• Wandering stars


  • Sun
  • Moon
  • Mercury
  • Venus
  • Mars
  • Jupiter
  • Saturn

  
• Aristotelian conceptions


  Motion is classified as natural or violent motion. In natural motion, a body will move and return to its natural state based on the body's nature and composition. In violent motion, a body needs an external force to move.
• Annual motion


  Apparent yearly motion of stars and other celestial bodies across the sky due to Earth's revolution
• Galilean conceptions


  The motion of a body is not due to its composition. The motion of a body can be described by measurement and changes in quantifiable variables like time and distance.
• Galileo's assertions


  • A body in uniform motion will move a distance proportional to the time it takes to travel
  • A uniformly accelerating body will travel at a speed proportional to time
  • An object in motion will keep moving, external force is not necessary to maintain motion
• Zodiac


  • Band of thirteen constellations seen along the Sun's ecliptic path
  • Constellations change through months as they are visible at different times in a year
• Reflection of light


  Phenomenon by which the incident light falling on the surface is sent back into the same medium

  
• Equinoxes


  Two days in a year when the sun crosses the celestial equator (near March 20 and September 22)
• Aristotle's assertion about vertical motion

  The velocity of a body is inversely proportional to the time it covers to travel a certain height
• Angle of incidence


  Angle formed by an incoming ray with the normal

  
• Galileo's assertion about vertical motion

  If two objects of different weights are dropped from a high point, both will hit the ground at the same time
• Law of reflection


  • The angle of incidence is equal to the angle of reflection
  • The incident ray, the reflected ray and the normal drawn at the point of incidence all lie in the same plane

  
• Solstices


  Two days in a year when the sun is at the farthest declination (north or south) from the celestial equator
• Precession


  Slow 'wobbling' of Earth's axis of rotation due to the gravitational pull of the Moon and Sun
• Aristotle's assertion about horizontal motion

  Bodies require force to maintain horizontal motion
• Diffuse reflection


  Reflection produced by rough surfaces

  
• Solar eclipse


  Occurs when the moon passes between the Earth and sun with the moon casting a shadow on the Earth's surface
• Lunar eclipse


  Occurs when the Earth is directly aligned between the sun and moon with the Earth casting a shadow on the moon
• Galileo's assertion about horizontal motion

  If there is no interference, a body in motion will keep moving in a straight line forever. External force is not needed to continuously move, it is needed to stop the motion.
• Normal line

  An imaginary line drawn perpendicular to the reflecting surface
• Aristotle's concept of projectile motion

  Antiperistasis - the resistance of a medium in response to the movement of a body
• Models of the universe

  • Ptolemaic system
  • Copernican system
  • Tychonic system
• Light travels in a straight line
• Ptolemaic system


  • Earth is the center of the universe
  • All other celestial bodies revolve around the Earth
  • Stars are located and fixed in the outermost celestial sphere
  • Utilized epicycles and deferent to explain retrograde motion

  
• Geometric optics


  Approximation of light treatment in which light waves are represented as straight-line rays

  
• Galileo's explanation of projectile motion

  Projectiles follow a curved path with a horizontal and vertical component
• Light can be considered as an electromagnetic wave, but this aspect will not be dealt with in this module
• Galileo's cannonball experiment


  1. Dropped objects reach the ground at the same time regardless of mass, size, and air resistance

  2. Discovered the principle of uniform acceleration
• Reflection of light


  1. Incident ray

  2. Reflected ray

  3. Normal

  
• Galileo's observations


  • Falling objects increase speed as they go down, this change in speed is acceleration
  • Acceleration is uniform regardless of mass, size, shape, and air resistance
  • Force is not necessary to sustain horizontal motion
  • Speed of a falling object is directly proportional to time traveled
  • Distance covered is directly proportional to the square of time interval
• Refraction of light


  • Bending of a wave when it passes from one medium to another due to differences in density
  • Incident ray, refracted ray, and normal to the interface of two media at the point of incidence all lie on the same plane
  • Ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant (Snell's law of refraction)

  
• Copernican system


  • Sun is the center of the universe
  • All planets including Earth revolve around the Sun
  • Only the moon revolves around the Earth
  • Stars are located and fixed in the outermost celestial sphere
  • Differences in orbital speed of planets explain retrograde motion

  
• Galileo's findings


  • Mass of an object is proportional to its resistance to move
  • Force is not necessary to keep an object in motion
• Refraction of light in real life

  • Mirage and looming
  • Swimming pool appearing shallower
  • Formation of rainbow
  • White light splitting into component colors in a prism

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


  An object at rest will remain at rest, and an object in motion will remain in motion, unless acted upon by an external force
• Tychonic system


  • Earth is the center of the universe
  • Moon and Sun revolve around Earth
  • All other planets revolve around the Sun
  • Stars are located and fixed in the outermost celestial sphere
  • Same explanation for retrograde motion as Copernican system

  
• Photon


  Smallest discrete amount or quantum of electromagnetic radiation, the basic unit of all light
• Newton's second law of motion

  The change in momentum of a body is equal to the magnitude and direction of the force acting upon it. Force is the product of mass and acceleration.