Calculate the Earth's radius | Physics

Suppose that, while lying on a beach near the equator
watching the Sun set over a calm ocean, you start a stopwatch just
as the top of the Sun disappears. You then stand, elevating your
eyes by a height H = 1.70 m, and stop the watch when the top of
the Sun again disappears. If the elapsed time is t = 11.1 s, what is
the radius r of Earth?

Solving the exercise from book 1 Fundamentals of Physics about finding the Earth's radius. #physics #astronomy #astrology