Explanation:
It is given that,
Speed of the ball, v = 10 m/s
Initial position of ball above ground, h = 20 m
(a) Let H is the maximum height reached by the ball. It can be calculated using the conservation of energy as :


h' = 5.1 m
The maximum height above ground,
H = 5.1 + 20
H = 25.1 meters
So, the maximum height reached by the ball is 25.1 meters.
(b) The ball's speed as it passes the window on its way down is same as the initial speed i.e. 10 m/s.
Hence, this is the required solution.
The concepts used to solve this problem are those related to the Pythagorean theorem for which we will calculate the distance and the pitch.
According to the attached diagram we have that the expression of the resulting displacement is

Therefore the resultant displacement of the girl is



Therefore the girl has displaced around of 5 blocks