I would ordinarily pass on a question as complicated as this one is.
But the lure of a bountiful 5 points at the end was too strong to ignore.
-- The acceleration of gravity on Earth is 9.8 m/s². That means that
no matter how fast or slow an object is already falling, it'll be falling
9.8 m/s faster 1 second later. In 2.75 seconds, its speed increases
by (9.8 x 2.75) = 27 m/s. Added onto the shove you gave it when you
threw it down, it's moving at 37 m/s when it hits the water.
-- The rock's falling speed was 10 m/s when you threw it, and 37 m/s
when it hit the water. It's average speed was (1/2) (10 + 37) = 23.5 m/s.
It spent 2.75 sec falling with that average speed. So the distance it fell
was (23.5 m/s) x (2.75 sec) = 64.6 meters.
