General Physics

• Relativity


  The study of how different observers measure the same event
• Inertial Frame of Reference

  A reference frame in which a body remains at rest and a body in motion moves at constant speed in a straight line unless acted upon by force
• Galileo Galilei and Isaac Newton


  • Developed the first correct version of classical relativity
• Albert Einstein

  • Developed the modern theory of relativity, the theory of special relativity
• Special Relativity


  The laws of physics are the same for everyone, no matter how they're moving, as long as they're moving at a constant speed. It also says that the speed of light is always the same, no matter how fast you're moving
• General Relativity


  Massive objects like planets and stars warp the space and time around them. When other objects move near them, they follow curved paths because of this warped space-time
• Einstein's First Postulates

  • States that the laws of physics are the same for all observers at constant speed relative to each other
  • The laws of physics are the same and can be stated in their simplest form in all inertial measurements are made
• Einstein's Second Postulates


  • States that the speed of light is constant and independent of the relative motion of the source
  • Speed of light is equal to 3 x 10^8 m/s in a vacuum
• Einstein's conclusion is that the laws of electricity and magnetism would not allow another speed for light
• Michelson and E.W Morley (Michelson - Morley)


  • Demonstrated the speed of light in a vacuum is independent of the motion of the earth about the sun
  • Light does not need a medium to carry it unlike sound
• Time Dilation


  • The phenomenon of time passing slower for an observer moving relative to an observer at rest
  • Time is longer and slower for those in motion. Thus time depends on the observer's relative motion
• Length Contraction


  • The shortening of the measured length of an object moving relative to an observer's frame
  • Distance depends on the observer's relative motion
• Radioactive Decay


  Reduces the number of radioactive nuclei over time
• Half life


  • The time in which half the original number of nuclei decay
  • Each nucleus has a 50% chance of living for a time equal to one half life
• Becquerel


  • The SI unit for decay per second
  • It is the small unit for activity
• Curie


  • Equal to 3.7 x 10^10 decays/second
  • It is a large unit of activity
  • Honor for Marie Curie's work on radium
• The activity of a source depends on two things: the amount of the radioactive substance and half life
• The more radioactive substances are present

  The more will decay per unit of time
• The shorter the half life

  The more decay per unit of time
• Rate of decay is proportional to the number of radioactive nuclei and inversely proportional to their half life
• Relativity


  The study of how different observers measure the same event
• Inertial Frame of Reference


  A reference frame in which a body remains at rest and a body in motion moves at constant speed in a straight line unless acted upon by force
• Galileo Galilei and Isaac Newton


  • Developed the first correct version of classical relativity
• Albert Einstein


  • Developed the modern theory of relativity, the theory of special relativity
• Special Relativity


  The laws of physics are the same for everyone, no matter how they're moving, as long as they're moving at a constant speed. It also says that the speed of light is always the same, no matter how fast you're moving
• General Relativity


  Massive objects like planets and stars warp the space and time around them. When other objects move near them, they follow curved paths because of this warped space-time
• Einstein's First Postulates


  • States that the laws of physics are the same for all observers at constant speed relative to each other
  • The laws of physics are the same and can be stated in their simplest form in all inertial measurements are made
• Einstein's Second Postulates


  • States that the speed of light is constant and independent of the relative motion of the source
  • Speed of light is equal to 3 x 10^8 m/s in a vacuum
• Einstein's conclusion is that the laws of electricity and magnetism would not allow another speed for light
• Michelson and E.W Morley (Michelson - Morley)


  • Demonstrated the speed of light in a vacuum is independent of the motion of the earth about the sun
  • Light does not need a medium to carry it unlike sound