Answer:
a) 
b) 
Explanation:
given,
n =1.5 for glass surface
n = 1 for air
incidence angle = 45°
using Fresnel equation of reflectivity of S and P polarized light

using snell's law to calculate θ t


a) 

b) 

Let
be the height of the building and thus the initial height of the ball. The ball's altitude at time
is given by

where
is the acceleration due to gravity.
The ball reaches the ground when
after
. Solve for
:


so the building is about 16 m tall (keeping track of significant digits).
Because the tip of the moon's shadow ... the area of "totality" ... is never more than a couple hundred miles across, It never covers a single place for more than 7 minutes, and can never stay on the Earth's surface for more than a few hours altogether during one eclipse.
If you're not inside that small area, you don't see a total eclipse.