Physics M1-M3.1

• Aphelion


  Earth is FAR from the sun
• Perihelion


  Earth is CLOSE to the sun
• Diurnal motion


  DAILY motion
• Annual motion


  YEARLY motion
• Precession of the equinoxes

  Slow rotation of the whole pattern of stars around the ecliptic axis
• Perihelion


  • Happens in early JANUARY
  • Earth moves FAST
• Aphelion


  • Happens in early JULY
  • Earth moves SLOW
• Rotation


  1. Spinning of the earth on its axis

  2. Axis - imaginary line from North to South pole; tilted 23.5˚

  3. 24 hours or 1 day
• Revolution


  1. Movement of the earth around the sun

  2. One complete revolution takes 365 1/4 days or 1 year
• Diurnal motion


  • DAILY motion of stars and other celestial bodies
  • Refers to the daily rising and setting of the sun
  • Rise - East
  • Set - West
  • Due to Earth's rotation
• Annual motion


  • YEARLY motion of stars and other celestial bodies
  • Due to Earth's revolution
• Precession of the equinoxes

  • 26,000 years
  • Hipparchus
  • Precession is caused by the gravitational pull of the sun and moon
• Precession of the equinoxes is a slow rotation of the whole pattern of stars around the ecliptic axis
• Kinematics


  A branch of mechanics that is the science of describing the motion of objects using words, diagrams, numbers, graphs, and equations
• Free-falling bodies


  • All objects fall at the same rate regardless of their weight
• Leaning Tower of Pisa

  • Galileo discovered through this experiment that the objects fell with the same acceleration
• Galileo stated that in the absence of air resistance all objects fall with the same uniform acceleration
• Inclined Plane Experiment


  • No force is needed to keep an object moving with constant velocity
  • Galileo explained that if there were no interferences, objects moving in a straight line will continue to move without the need of a FORCE
  • Push or pull is NOT needed for the object to move
• Projectile motion


  It is a combination of uniform forward motion and free-fall motion
• Galileo was the first person to describe projectile motion, accurately. He segregated motion into horizontal and vertical components
• If the projection angle is other than 90o, the ball follows curved paths
• If the projection angle is 90o with horizontal, the ball follows a vertical path
• Nothing accelerates a projectile horizontally, so horizontal acceleration is always zero
• Vertical and horizontal components of projectile motion are independent of each other
• A projectile follows a two-dimensional motion: vertically or horizontally, the motion can be studied as a combination of two simultaneous one-dimensional motions
• Galileo Galilei


  An Italian astronomer who used his own telescope to make astronomical observations and found significant evidence supporting the HELIOCENTRIC MODEL
• Galileo's views on motion


  • Observation & experiment
  • Free falling bodies
  • Projectile motion
  • Uniform motion
• Aristotle's views on motion


  • Push and pull
  • Natural/resting place
  • Based on composition - earth/land, water, fire, and air
  • Heavier objects fall faster
  • Force is required in Violent motion
• Galileo's views on motion


  • No push or pull is required to keep an object from moving
  • No natural place/resting place
  • Air resistance - objects fall at the same rate regardless of their weight
  • Force is not necessarily required for Violent motion
• Kinematics


  A branch of mechanics that is the science of describing the motion of objects using words, diagrams, numbers, graphs, and equations
• Celestial bodies


  Objects in space such as the moon, sun, planets, and stars
• Celestial


  Outer space; heaven; sky
• Terrestrial


  Earth; land
• Terrestrial sphere


  • Made of four elements: earth, air, fire, and water, subject to change and decay
• Celestial spheres


  • Made of a fifth element, an unchangeable aether
• Ancient Greeks believed the cosmos or the universe was divided into two realms - celestial and terrestrial
• Motion of celestial realm


  • Perfect and circular, revolving around Earth
• Motion of terrestrial realm

  • Unstable and imperfect, requires a cause
• Natural motion


  Where objects tend to go back to their natural state, based on the element that composes them, does not require an external cause
• Violent motion


  Motion requires force, refers to the action necessary to move things horizontally, does not happen without action