• QUESTIONS BEFORE LECTURE 19

now think about these, which are hard

• Contrast the two ways to show that clocks slow down along the line of motion. The telephone pole stopwatch makes a logical chain with Lec 18. Does the tick-tock light clock? How do they differ?
• What two things does the difference in two clock settings a distance x apart depend on? Explain why.
• What is the essence of the explanation that the driver and the garage keeper indeed see the front door open in different orders relative to the closing of the rear door? This can actually be answered with a brief sentence.