Alight ray goes from a point a (in a medium of index n1) to a point b
(in a medium of index n2). the two media are separated by a dioptric plane surface.
the axis system is oxyz and the separation surface is the plane xoy, with a=(0,0,a)
and b=(d,0,-b).
by applying the fermat’s principle, find, in the xoy plane, the position of a point
m where the ray passes from medium (1) to medium (2). show that the 2 nd
descartes’ law is recovered.

Aball is thrown from the top of a building with an initial velocity of 21.9 m/s straight upward, at an initial height of 51.6 m above the ground. the ball just misses the edge of the roof on its way down, as shown in the figure. (a) determine the time needed for the ball to reach its maximum height. (b) determine the maximum height. (c) determine the time needed for the ball to return to the height from which it was thrown, and the velocity of the ball at that instant. (d) determine the time needed for the ball to reach the ground. (e) determine the velocity and position of the ball at t = 5.35 s.