Answer:
Part A
The intensity is
Part B
The intensity is 
Explanation:
From the question we are told that
The intensity of the light detected by first eye is 
Now at initial state according the question the light ray is perpendicular to the eye so it means that it is at 90° the eye
Now the first question is to obtain the intensity the first eye (the first in this case is the one focused on the light )would detect when the head is rotated by 20° its previous orientation
This is mathematically evaluated as

Now the second question is to obtain the intensity the first eye (the first eye in this case is the one that is not focused on the light )would detect when the head is rotated by 20° its previous orientation
Now in this case the angle between the eye and the light is 90-20 = 70°
So


There is no image!?...was there meant to be something attached?
Answer:

Explanation:
Regardless of the initial velocity of the pebble, the acceleration of the pebble is equal to the gravitational acceleration which is equal to 9.8 m/s2 towards downwards direction.
This can be shown by Newton's Second Law. According to the law, the net force applied on an object is equal to mass times acceleration of that object.
During the downward motion, the only force acting on the pebble is the gravitational force, hence its acceleration is equal to gravitational acceleration.