Time for rock to fall second half of cliff distance

[Carol-Anne]

Homework Statement

a rock is dropped off a cliff and falls the first half of the distance to the ground in 2.0 seconds.

Homework Equations

How long will it take to fall the second half?

The Attempt at a Solution

i thought if i took the square root of two and then subtracted that from 1/2t that would be the answer but apparently not

 

[berkeman]

Welcome to the PF.

Please write out the equations of kinematic motion in a constant acceleration force field (gravity). That will help you to start to show your Attempt at the Solution. Thanks.

 

[vela]

The Attempt at a Solution

i thought if i took the square root of two and then subtracted that from 1/2t that would be the answer but apparently not

What was your reasoning here?