Answer:1.902 m
Explanation:
Given
height of apartment=1.5 m
It takes 0.21 sec to reach the bottom from apartment
So
[tex]s=u_1t+\frac{gt^2}{2}[/tex]
[tex]1.5=u_1\times 0.21+\frac{9.81\times 0.21^2}{2}[/tex]
[tex]u_1=6.11 m/s[/tex]
i.e. if ball is dropped from top its velocity at window is 6.11 m/s
So height of upper floor above window
[tex]v^2-u^2=2as[/tex]
where s= height of upper floor above window
here u=0
[tex]6.11^2=2\times 9.81\times s[/tex]
[tex]s=\frac{6.11^2}{2\times 9.81}[/tex]
s=1.902 m