Answer:
d = 80 m
Step-by-step explanation:
It is given that,
A rock falls for 4 seconds.
We need to find how far did it fall.
let it cover d distance.
Using equation of motion to find it :
![d=ut+(1)/(2)at^2](https://img.qammunity.org/2021/formulas/physics/college/v525it91ua1qp9pi8p6scw2ez8eyqs85j6.png)
Here, u = 0 (at rest initially)
a = g
![d=(1)/(2)gt^2\\\\d=(1)/(2)* 10* 4^2\\\\d=80\ m](https://img.qammunity.org/2021/formulas/physics/college/rcjsjz0n3emup16j2j8aniddk3yle22a6f.png)
It will fall at a distance of 80 m.