Answer:
1.038s
Step-by-step explanation:
To solve this problem we use the following equation for the free fall movement:

where
is the height,
is the initial velocity, in this case since the rock was just dropped,
,
is the acceleration of gravity of the planet in this case mars, thus g will be:
. And
is time, wich is what we are looking for.
Clearing the equation for
:

since




we have
and from the problem we have that

thus:


The time it takes is 1.038s