A small earthquake starts a lamppost vibrating back and forth. The amplitude of the vibration of the top of the lamppost is 6.6cm at the moment the quake stops, and 8.4 ss later it is 2.1 cm.

Part A

What is the time constant for the damping of the oscillation? Express your answer with the appropriate units.

Part B

What was the amplitude of the oscillation 4.2s after the quake stopped? Express your answer with the appropriate units.