A rock is dropped from a 164-m-high cliff. How long does it take to fall (a) the first 82.0 m and (b) the second 82.0 m

Explanation:

Given

Rock is dropped from a height of

Rock is drooped so initial velocity is zero i.e.

Time taken to fall is given by

where  

y=displacement

u=initial velocity

a=acceleration

t=time

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

time taken