1. 1 Relativity  H1: Introduction to relativity

2. 2 Motion is relative  Whenever we talk about motion, we must always specify the vantage point from which motion is being observed and measured.  To measure the speed of an object, we first choose a frame of reference and pretend that we are in that frame of reference standing still.  Then we measure the speed with which the object moves relative to us-that is, relative to the frame of reference.

3. 3  All laws of mechanics remain the same in a frame moving at a constant velocity.  In other words: Newton's laws can be used in uniformly moving frames, as if those frames did not move. The theory of relativity modifies those laws when the magnitude of v or v0 approaches the speed of light in vacuum, but all motions studied here are much slower.

4. 4 Galilean transformation  (mechanics) A mathematical transformation used to relate the space and time variables of two uniformly moving (inertial) reference systems in non-relativistic kinematics.  We use Galilean transformations when objects are not accelerating

5. 5 Galilean transformations

6. 6 Postulates of the Special Theory of Relativity  All motion is relative, not to any stationary hitching post in the universe, but to arbitrary frames of reference.  A familiar experience to a passenger on a train who looks out his window and sees the train on the next track moving by his window.  The important point: If you were in a train with no windows, there would be no way to determine whether the train was moving with uniform velocity or was at rest.