Answer:
Explanation:
Given
Rock is dropped from a height of [tex]h=164\ m[/tex]
Rock is drooped so initial velocity is zero i.e. [tex]u=0[/tex]
Time taken to fall [tex]82\ m[/tex] is given by
[tex]y=ut+\frac{1}{2}at^2[/tex]
where
y=displacement
u=initial velocity
a=acceleration
t=time
[tex]164=0+\frac{1}{2}gt^2[/tex]
[tex]t=\sqrt{\frac{2\times 82}{9.8}}[/tex]
[tex]t=4.09\ s[/tex]
Now time taken to fall another 82 m
We can calculate this time by first calculating time taken to cover 82+82 m and then subtracting the time taken to cover 82 m
[tex]t_2=\sqrt{\frac{2\times 164}{9.8}}[/tex]
[tex]t_2=5.78\ s[/tex]
time taken [tex]=t_2-t=5.78-4.09=1.69\ s[/tex]
