Answer
given,
height of window = 4 m
time taken to travel = 1 s
acceleration due to gravity = 9.8 m/s²
[tex]s = ut + \dfrac{1}{2}at^2[/tex]
[tex]u = \dfrac{s - \dfrac{1}{2}at^2}{t}[/tex]
[tex]u = \dfrac{4 - \dfrac{1}{2}\times 9.8\times 1^2}{1}[/tex]
u = -0.905 m/s
initial velocity of ledge v = 0
now,
v² = u² + 2 a s
(-0.905)² = 0 + 2 × 9.8 ×s
s = 0.042 m