Answer: 15.87 m
From the equation of motion:

where,
is the distance traveled,
is the initial velocity,
is the acceleration and
is the time.
The rock free falls under gravity. Initial velocity,
, 
It took
for rock to hit the water.
Substitute the values in the given equation:

Hence, the water is 15.87 m below the top level of the well.
The uniform microwave radiation remaining from the Big Bang.
So, your body is always having background radiation and that means space!
Answer:disequilibrium
Explanation:
When the net force is not zero it is called disequilibrium
Most of our brain activity is unconscious
The answer is 509 m.
Let point B be 253 m from point A. Let point C be 64 s away from point B.
Let d1 be the displacements from point A to point B and d2 and be the displacements from point B to point C
Step 1. Calculate the displacement from the point B after 64 s.
Step 2. Calculate the displacement from the point A by summing up two distances (d1 and d2).
Step 1.
v = d2/t
v = 4 m/s
d2 = ?
t = 64s
____
4 = d2/64
d2 = 64 * 4 = 256 m
Step 2:
d = d1 + d2
d1 = 253 m
d2 = 256 m
d = 253 + 256 = 509m