Physical Science

• Kepler's first law

  Planets move around the Sun in elliptical orbits
• Eccentricity


  Measure of how flattened an ellipse is, between 0 (circle) and 1
• Kepler's third law


  The square of a planet's period is proportional to the cube of its mean distance from the Sun
• A planet is farther from the Sun


  Its orbit is slower
• Earth travels fastest when closest to the Sun, in early January
• Kepler's laws of planetary motion


  • Describe the motions of planets in the solar system
  • Proved crucial to Isaac Newton in formulating the law of gravitation
  • Apply not only to gravitational but also to all other inverse-square-law forces
• Physics is a mathematical science
• The underlying concepts and principles of physics have a mathematical basis
• Throughout the course of our study of physics, we will encounter a variety of concepts that have a mathematical basis associated with them
• While our emphasis will often be upon the conceptual nature of physics, we will give considerable and persistent attention to its mathematical aspect
• The motion of objects can be described by words
• Even a person without a background in physics has a collection of words that can be used to describe moving objects
• Words and phrases used to describe the motion of objects

  • going fast
  • stopped
  • slowing down
  • speeding up
  • turning
• In physics, we use these words and many more
• We will be expanding upon this vocabulary list with words such as distance, displacement, speed, velocity, and acceleration
• These words are associated with mathematical quantities that have strict definitions
• Categories of mathematical quantities used to describe motion

  • Vector
  • Scalar
• Scalar


  Quantities that are fully described by a magnitude (or numerical value) alone
• Vector


  Quantities that are fully described by both a magnitude and a direction
• The remainder of this lesson will focus on several examples of vector and scalar quantities (distance, displacement, speed, velocity, and acceleration)
• As we proceed through other units, the discussion will often begin by identifying the new quantity as being either a vector or a scalar
• Physics is a mathematical science. The underlying concepts and principles have a mathematical basis.
• Throughout the course of our study of physics, we will encounter a variety of concepts that have a mathematical basis associated with them.
• While our emphasis will often be upon the conceptual nature of physics, we will give considerable and persistent attention to its mathematical aspect.
• The motion of objects can be described by words.
• Even a person without a background in physics has a collection of words that can be used to describe moving objects.
• Words and phrases used to describe the motion of objects

  • going fast
  • stopped
  • slowing down
  • speeding up
  • turning
• In physics, we use these words and many more.
• Words used in physics to describe motion

  • distance
  • displacement
  • speed
  • velocity
  • acceleration
• These words are associated with mathematical quantities that have strict definitions.
• Scalar


  Quantity that is fully described by a magnitude (or numerical value) alone
• Vector


  Quantity that is fully described by both a magnitude and a direction
• The remainder of this lesson will focus on several examples of vector and scalar quantities (distance, displacement, speed, velocity, and acceleration).
• As we proceed through other units at The Physics Classroom Tutorial and become introduced to new mathematical quantities, the discussion will often begin by identifying the new quantity as being either a vector or a scalar.