Question

why the shadows of object on the earth change their position during the day

Answer 1

It is a natural phenomenon. As sun keep on changing its position,similarly our shadow is formed behind us and keep on changing its position because of sunlight from different directions. At the time of sunrise if a man is facing the East ,his shadow will be towards West.At the time of sunset the shadow will always formed in the East. If a man stands facing North ,at the time of sunrise his shadow will be towards his left and at the time of sunset it will be towards his right. At 12:00 noon,the rays of the sun are vertically downward hence there will be no shadow.