Describe the time of day that an early explorer might have planned to enter a harbor and when he might have planned to leave

The speed of light can be used to measure the

How is zig zagging a form of acceleration?

Estimate the schwarzschild radius (in kilometers) for a mini-black hole formed when a superadvanced civilization decides to punish you (unfairly) by squeezing you until you become so small that you disappear inside your own event horizon. (assume that the your weight is 50 kg)