we measure shadows ......
      to calculate the circumference of the earth,
      as Eratosthenes calculated it 2250  years ago !!! .....

 

Eratosthenes experiment in High School Novska

We have measured the length of a shadow of a stick one meter (100 cm) long at solar noon on 19th March 2015:

                  102 cm, 102 cm, 103 cm, 102 cm, 103.5 cm, which is aproximately 102.5 cm.

Thereby we got the angle: 45.56726641° = arctg(102.5/100) between sun rays and the vertical stick.

Our distance from Equator is: 5016.83km

So, the circumference of the Earth is:  (360°/45.56726641°)*5016.83 = 39 635 km (the real number is 40 075 km).

 

 

Eratosthenes experiment in 2nd High School of Edessa