Summary

• Consequence #2: synchronization
• Consequence #3: time dilation
• Consequence #4: Length contraction

• Class Quiz
  
  
  
  
• Spacetime
  • pole through barn scenario
  • the fourth dimension
    Example #1
    
    Example #2
    
  
  
  
  
• Relativistic mechanics
  • Newton's second law
  • kinetic energy of a particle
  • E₀ = m c²
  
  

kw5 10.
With what speed (relative to earth) would Buck Rogers have to travel in order to age only 5 years in 500 years (on earth clocks) of traveling?
A. 0.99c               B. 0.995c
C. 0.9999c           D. 0.99995c
Answer







kw5 10.
Mary claims that the engine of Ed's fast moving train came out of a tunnel at the same time the caboose entered. Does Ed agree?
    A. Yes
    B. No - the engine came out first.
    C. No - the caboose entered first.
Answer







kw5 10.
According to Ed, which is longer, the train or the tunnel?
    A. The train is longer than tunnel.
    B. The tunnel is longer than train.
    C. They are the same length.
Answer







 



D. 0.99995c













 



B. No - the engine came out first.
Mary argues that the Ed only thinks the engine emerged first because he is moving fast towards that signal and away from the caboose signal. Ed claims he's at rest and Mary only thinks the signals are simultaneous because she is moving fast towards the caboose signal and away from the engine signal.













 



A. The train is longer than tunnel.
Ed sees his train as "normal" in length but the approaching tunnel is contracted and appears shorter than the train. He does not think the train is ever fully in the tunnel, but Mary does.