Constant Relative Velocity

Formula 1 Formula 2

In the above demonstration you will see the coordinate frame of a stationary observer (rest frame).  Another observer is moving at a constant velocity of 0.9c.  Assume that both reference frames use the same units for time and distance.  Upon choosing a formula, a red ball will appear at the origin of the rest frame and the columns of the table will fill with data.  The ball moves with constant velocity in both frames.  u and u' are the velocities of this ball in each reference frame.  Remember that c = 1.

Section 2 Exercises:

  1. What is the velocity of the ball in the stationary frame?
  2. By choosing the different links two different formulas are used to calculate u'.  Which of the formulas gives the correct values for the velocity of the ball in the moving frame?
  3. Confirm for two data points that the metric (delta s)2 is invariant for the correct choice of addition of velocity formula.  Show your calculations.