The Above Phenomenon is a great example of TOTAL INTERNAL REFLACTION, Which comes in account when light travels from denser medium to rearer medium, after some specific angle it again reflacts into the denser medium. Similar kind of activity happens in desert area called Mirage or Marichica.

Speed of light = 3x10⁸ m/s. Distance between the earth & the Sun is = 150000000 KM. So the time taken by light to cover this. Distance is = 150000000000 m/3x110⁸ m/s => 500 sec. /60 => 8 min. 20 sec.

Earth revolve around the sun in anticlockwise direction and rotate about an its axis so the motion of earth is west to east with respect to star so according to the theorem of relativity we assume that star is moving east to west whenever the star is static with respect to earth and no one atmoshphere is moving.

When a liquid is contained in a vessel, it exerts force at all points on the sides and bottom of the vessel. The force per unit area is called intensity of pressure. Mathematically, intensity of pressure,
p = P/A
where
P = Force acting on the liquid, and
A = Area on which the force acts.

The intensity of pressure may be expressed either in N/m², N/mm² or in metres of liquid or mm of liquid. Intensity of pressure is also expressed in pascal (briefly written as Pa), such that
1 Pa= 1 N/m²; 1 kPa= 1 kN/m² and 1 MPa = 1 MN/m²= 1 N/mm²